Find answers to Frequently Asked Questions for First Generation Firebirds that have been asked and answered on FGF. Special thanks needs to be given to all the FGF members who took the time to respond to other member's questions.
Wheels, Brakes, and Axle - All
Reference:
- 1968 Pontiac Service Manual Section 3 Page 3-5
Q: Traction Bars for 1967 and 1968
I was recently browsing the archives and seen information about what firebirds came with traction bars. I am confused to what models got what type of traction bar.
I have a 1967 Firebird convertible with a 326 two barrel but I have two traction bars. This car is not a high output model. And to my knowledge this car is original.
A: 68s didnt have traction bars.
1967s breakdown:
-
OHC-6 1bbl auto. none (exception is rear end ratio 323 or higher) OHC-6 1bbl man. RH side
-
OHC-6 4bbl. auto. RH side
-
OHC-6 4bbl. man. both sides
-
V-8 2&4bbl. auto. RH side
-
V-8 2&4bbl. man. both
I also found that the rear end ratio or type in this case determined the option of one or two bars or radius rods. i.e. if a car has a 4 pinion rear end it will have both bars. this is for posi and open 4 pinion rears.
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Content last modified: January 22, 2014 at 10:17 am
Q: Axle Codes for 1967 and 1968
How do I identify the Sales Code for the axle ratio that is shown on the Billing History cards.
A: In 1967, the ratio will be shown in the box marked 74 and in 1968, it will be shown in box 37. In both instances, the codes used to identify the axle ratio will be the same and they are as follows:
C = 2.56:1
D = 2.78:1
E = 2.93:1
F = 3.08:1
G = 3.23:1
H = 3.36:1
K = 3:55:1
P = 3.90:1
S = 4.33:1
Note: Do not confuse these Sales Codes with the two-digit code that is stamped on the axle tube.
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Content last modified: January 24, 2014 at 9:50 pm
Q: Rear End Code Facts
I am confused by the codes found on the rear end.
A: After reading all the comments, I thought I’d better give some facts. The 1967 Firebird axle housings have the loops (where control arm bushings would mount) on top of the center chunk as if they were getting A-body control arms, but they also have the spring perches for leaf springs, and the brackets for the factory style “traction bars”. There should also be a date code cast into the center section somewhere. In 1968 they left off the control arm bushing loops and the traction bar mounts, but seemed to use the same codes as 1967. In 1969 the date code position moved from one side of the center section to the other, but I can’t get to my rearend housings to see which are which. Another change from 1968 to 1969 was the addition of flattened spots on top of the axle tubes where the snubbers meet the housing, 1967 and 1968 did NOT have the flat spots. Again, check your cast date codes if at all readable.
Also, all 3 years had the 2-letter stamped code in roughly the same position, about 3-5 inches to the LEFT of the center section, on the rear of the left axle tube (left being the driver’s side of the car). Many times it is obscured by the steel brake line – you’ll need to loosen the clip welded to the axle tube and raise the brake line a bit to see it.
The 1969 codes were different. Here’s the list (first the open ratio, then the posi):
1967, 1968, and 1969 Axle Identification Codes |
|||||||
---|---|---|---|---|---|---|---|
Ratio |
1967 |
1968 |
1969 |
||||
Std. Diff. Code |
Lock Diff. Code |
Std. Diff. Code |
Lock Diff. Code |
Std. Diff. Code |
Lock Diff. Code |
||
2.56 |
XB |
UN |
XB |
UN |
YB |
ZB |
|
2.78 |
XC |
UP |
XC |
UP |
YC |
ZC |
|
2.93 |
XD |
UR |
XD |
UR |
YD |
ZD |
|
3.08 |
XE |
US |
XE |
US |
YE |
ZE |
|
3.23 |
XF |
UT |
XF |
UT |
YF |
ZF |
|
3.36 |
XG |
UV |
XG |
UV |
YG |
ZG |
|
3.55 |
XH |
UW |
XH |
UW |
YH |
ZH |
|
3.90 |
– |
UX |
– |
ZP |
– |
ZK |
|
4.33 |
– |
UY |
– |
ZR |
– |
ZM |
I hope this clears up some confusion and misinformation. Whenever possible, ask about date codes (same style of codes as engine parts), axle codes (rear of left tube), spring perch depth (67 Monoplates are shallow), whether it has the extra brackets for traction bars (67 only), or if there are flattened spots on top (69 only).
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Content last modified: December 8, 2017 at 4:11 pm
Q: Custom Trim Option (Code 554)
My billing history indicates my 1968 came with custom trim. What was included with this option?
A: For the 1968 Firebird, the Custom Trim Option (554) included the following….
Custom Seat Covers (Morrokide and stitched knit vinyl)
Custom Molded Door and Quarter Trim Panels, Assist Bar (above Glovebox) Dual Horns, Deluxe Wheel Covers, Deluxe Steering Wheel, Custom Pedal Trim, Front & Rear Wheel Opening Moldings, Drip Rail Mldgs (Coupes), Windshield Pillar Garnish Mldg. There are some who have been saying (in error) that only those cars with the Custom Trim Option had the etched white ‘Bird’ on the front side glass; this is not so and has been proven by many original STANDARD trim Firebirds.
The RH sideview mirror was not a part of the Custom Trim Option.
Many owners upgraded or opted to delete certain things beyond the Custom Trim Option (wheel opening mldgs, wheel covers, steering wheel). Additionally, all of the components of the Custom Trim Option could be ordered separately on a Standard Trim car except for the Custom Seats and Trim Panels and Assist Bar
A: Use following link to find more information about the Custom Trim Option on FGF: More Information
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Content last modified: January 25, 2014 at 10:11 am
Q: Rear Axle Code Location
On a safe t track rear axle where is the two letter code stamped?
A: Axle code should be on the left (drivers) side of the axle housing about 6 inches give or take from diff. cover.
A: The code is stamped on the drivers side axle tube facing the rear. This code took me forever to find it is to the left of the brake clip. You must do a lot of sanding to find it.
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Content last modified: January 21, 2014 at 9:26 pm
Q: Axle Codes 1967-1968
I received a note concerning axles and how to identify the Sales Code for the axle ratio that is shown on the Billing History cards.
A: In 1967, the ratio will be shown in the box marked 74 and in 1968, it will be shown in box 37. In both instances, the codes used to identify the axle ratio will be the same and they are as follows:
C = 2.56:1
D = 2.78:1
E = 2.93:1
F = 3.08:1
G = 3.23:1
H = 3.36:1
K = 3:55:1
P = 3.90:1
S = 4.33:1
Note: Do not confuse these Sales Codes with the two-digit code that is stamped on the axle tube.
I hope that this information helps answer most axle ratio related questions.
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Content last modified: January 21, 2014 at 9:27 pm
Q: Rearend Decode 1967
I would like to know how to tell if the rearend of my 1967 car is original to this particular model year, what can i look for on the housing that will help me identify the original numbers’s matching rear.
A: From the 1967 Firebird Supplement to the 1967 Pontiac service manual:
“Eight different axle ratios are available from the Firebird models. They can be identified by the two-letter code stamped on the rear of the L.H. axle tube”.
Here are the codes:
XB – 2.56 open
XC – 2.78 open
XD – 2.93 open
XE – 3.08 open
XF – 3.23 open
XG – 3.36 open
XH – 3.55 open
UN – 2.56 limited slip
UP – 2.78 limited slip
UR – 2.93 limited slip
US – 3.08 limited slip
UT – 3.23 limited slip
UV – 3.36 limited slip
UW – 3.55 limited slip
UX – 3.90 limited slip
If the rear end is original, the two letter code will tell you what axel ratio you have and whether it is an open or limited slip rear end.
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Content last modified: January 21, 2014 at 9:36 pm
Q: Find the Rearend Gear Ratio
Does anyone know how to find the rearend gear ratio on a 1967 firebird. (Besides pulling the cover off and counting teeth.) Any help is appreciated.
A: Take a piece of chalk and mark a line from the driveshaft yoke up to and on the differential housing. without moving the tire pick a reference spot on the car body near the rear tire (a screw or bolt, etc.) and mark the tire at this reference spot. Now, slowly rotate the tire while counting the number of times the drive shaft rotates past its’ reference mark. The rear gear ratio is the number of times the drive shaft rotates divided by the number of rotations the wheel rotates. example: drive shaft: 17, tire: 5… 17/5=3.4 so the rear gear ratio is 3.4:1. Good luck.
A: Look on the rear facing side of the left hand (driver’s side) half of the rear axle, about half way between the drum and the pumpkin. There should be a two letter code there. You may need a wire brush to clean it off to see it. Here is how you decode:
POSI CODES OPEN CODES
UN 2.56 XB
UP 2.78 XC
UR 2.93 XD
US 3.08 XE
UT 3.23 XF
UV 3.36 XG
UW 3.55 XH
UX 3.90
UY 4.33
Also, Here are the gear ratios for TH400 and Powerglide:
Power Glide 1st = 1.76 2nd = 1.00 Rev = 1.76
TH400 1st = 2.48 2nd = 1.48 3rd = 1.00 Rev = 2.00
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Content last modified: January 21, 2014 at 10:00 pm
Q: Rally II Wheel Codes
Does someone know the correct codes for Rally Rims? Specifically, I heard there was a different code for rims on drum versus disc.
A: Check out the Classic Pontiac Server web site: http://www.pontiacserver.com/wheels.html It is a fairly comprehensive page dedicated to pontiac rims and codes. Another site with good information about all the codes on a rim: http://www.wallaceracing.com/rally-wheel-date-code.htm
A: Parts book published in 1971 says 1967 used JA for disc and JC for drums 68 was JC for all. Try and figure this one out. All the parts for disc were the same for 1967 and 1968 so what made the difference I don’t know. A-body was just as confusing.
Application | Size | Style | Bolt Circle Diam | Code | GM Part Nm |
---|---|---|---|---|---|
1967 Firebird | 14×6 | Plain Steel | 4.75″ | ||
1967 Firebird | 14×6 | Rally I | 4.75″ | JB | 9787860 |
1967 Firebird w/Disc Brakes | 14×6 | Rally II | 4.75″ | JA | 525708 |
1967 Firebird w/Drum Brakes | 14×6 | Rally II | 4.75″ | JC | 546495 |
1968 Firebird | 14×6 | Plain Steel | 4.75″ | HG HK | |
1968 Firebird | 14×6 | Rally II | 4.75″ | JC | 546495 |
1969 Firebird | 14×6 | Plain Steel | 4.75″ | ||
1969 Firebird | 14×6 | Rally II | 4.75″ | JC | 546495 |
1969 Firebird | 14×7 | Plain Steel | 4.75″ | 362052 | |
1969 Firebird | 14×7 | Rally II | 4.75″ | JK | 525709 |
The 1968 Rally II had the wheel rim code on outside of the rim just next to the valve stem (see picture below):
For the 1968 Rally II, there were codes on the inside of the rim (flat part that connects both outside and inside of rim) which included the date code, plant code, inner wheel code (JJ), and size (14 x 6).
Key Words: Ralley II, Rally II, Rallye II, Wheel Codes, Rim Date Codes
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Content last modified: February 24, 2014 at 10:15 am
Q: Gear Ratio Calculations
I was trying to figure out my differential gear ratio. So I did as suggested and marked the axle and the tire and counted revolutions. I came up with two sets of numbers where the marks both came back to the starting point at the same time.
Axle revolutions = 26
Tire revolutions = 19
Axle revolutions = 41
Tire revolutions = 30
If I did the math right the ratio is 1.37.?
What is this? How can it be so low(numerically). No wonder the car seems to be a bit of a dog out of the hole. Did I do this right? Can anyone explain why someone would knowingly do this to a 400?
Note: 1968 Firebird, 400, auto. Not the original rear-end (from external observations, specifically no code where everyone says there should be a two letter code)
A: If this is a non-posi rear (must be) then you should have seen the other tire turning the opposite direction to the one you were turning. In this case, the number you got is 1/2 of the numeric gear ratio, making yours not 1.37 but 2.74 which means it is probably 2.78 which is a standard Pontiac Ratio.
Why would someone do this? High top Speed? Good Mileage? Who knows?
A: First you need to 1 (spin the axel and count the yoke revolutions) and not 2 (axel and tire) if you ment the first sorry. But sounds like you looked at the second and that is why you got the reading you did….
A: Are you sure that the yoke and wheels came back to the “exact” mark? In this case, close doesn’t count. If it is a non-posi unit, did you block one side so it would not spin? Take another look.
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Content last modified: January 22, 2014 at 9:23 am
Q: Choosing the Right Gear Ratio – Revisited
I’m looking for recommendations for the optimum gearing on my differential. I have a 1968 firebird convertible with a 350. Non-stock changes are – TH400, transmission, Rochester Q-jet, headers, P22560 tires and cast iron Pontiac intake. I presently have 2.78 gears and the car is pretty doggy.
I don’t really want to modify the engine or put in a higher stall converter. I am thinking of putting in either 3.23 or 3.55 gears. I do mostly around town driving but occasionally go out on the highway at 60-70 MPH. Does anyone have any suggestions on what is a good ratio?
A: I just went through the same thing with a 2.56 rear and picked 3.23 as a good all around ratio. Should run around 2600-2700 RPM at 60 MPH where a 3.55 would run 2900-3000 or so (ballpark numbers).
Also, keep in mind that if you are simply planning on changing gears that you can’t go any higher than 3.23 without changing the housing, or so I’ve read.
If you are planning a whole rear end swap, you might want to consider using a rear out of a 2nd gen car. The overall width is about 1″ wider, and you will have to have the spring perches cut and re-welded but the 8.5 inch rear and the posi unit are much stronger. Also, these rears are more common and Cheaper than 1st gen rear ends.
FYI…the code PX was used from 1976 to 1981 (or something like that) for a 3.23 Posi.
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Content last modified: January 22, 2014 at 9:27 am
Q: Rear Axle Gear Swaps 1968
Now for a question. I have 2:56 gears in my 1968 does anyone know what ratios I can go to without changing the differential? Is 3:23 or 3:73 a possibility?
A: Not with your differential case! Break out your trusty 1968 Factory Service Manual, and turn to the pages on rear axles. They have descriptions of the available axles, and a chart for how the cars were equipped with each ratio with the 2-letter codes stamped on the axle tubes. Mine (for 1969, same parts, different 2-letter codes) states that there were 3 differential cases (by ring gear mounting dimension, plus others for posi/non-posi), the first is for 2.56 and 2.78, the second is for 2.93, 3.08, and 3.23, then the third is for 3.36, 3.55, 3.90 and 4.33 ratios. This is for using original gears. The 3.90 and 4.33 used ONLY the 4-pinion locking diff case, the 3.36 and 3.55 posi used a 2-pinion case, or could be had in a non-posi type also. The 3.08 and 3.23 axles are not too uncommon, so you may want to look for one of those. I probably have a couple non-posi units kicking around here. Another choice is to see what the aftermarket offers, maybe Richmond Gear has something that would work with your differential case, although it might not go higher than 3.23.
Here I go again suggesting everybody get as much factory information as you can get your hands on! The factory service manuals are available in reprint, you can’t tell it from an original. Get it while you can!
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Content last modified: January 22, 2014 at 9:28 am
Q: Rear End Gears Swap
1) I want to be able to change to “highway” gears when I plan a long road trip, and then put the others back in when we get home. Is this possable?
2) If the rear ends from those other Pontiac models are a direct bolt-in, will the gears out of them swap into my rear as well?
A: Have you done this before? Gear swaps require some considerable skill to perform. Getting the lash and tooth engagement correct are probably the toughest part. A dial indicator would be among some of the specialized tools you would need. So, figure on $250 for gears, another $100 for tools, or $250 to get a shop to do the install. Going from 3:23 to 3:08 or even 2:73 shouldn’t require a different carrier. Figure a weekend to do it yourself, for the 1st time, and then half a day once you get the process down.
Excessive gear noise, and overheated fluid are common signs that a mistake was made.
As you want to hang onto you lower gearset, my suggestion would be to either get a second rear end (replacing the rear ends would probably consume less time than changing gears), or consider some type of overdrive. You didn’t mention whether you had a stick shift or an automatic. You could replace the automatic with a 200R, or the stick trans with a T5 or Tremec. Either will get you an overdrive, reducing your highway RPMs. Of course, this would be more costly at first, but consider the cost of 3 or 4 gear changes.
My buddy, who has 3:73 gears in his 65 El Camino, uses a taller tire (235/70s) mounted on a spare set of wheels for the roadtrips. He carries his cruising wheels and tires (225/55) in the bed, and we swap them when we get to our destination. This gets him what amounts to a taller gear that makes the RPMs at highway speed (2700-3000) a bit more liveable.
2)The 1st generation Firebirds use an 8.20″ 10 bolt unit that was unique to the Pontiac and Buick cars. There is a corporate 8.20 whose gears will not interchange, used in Chevys. In 1970, GM went to one 8.50 10 bolt carrier across the board. This unit can be found in Novas, Apolos, Omegas, and Venturas, 1970 thru 74, and 2nd generation Firebirds and Camaros. The second generation F body rears will fit under your car, but you will need to relocate and replace the spring perches, and use a unique rear u-joint.
Luckily, tall gears are plentiful in these cars.
There are 2 other 10 bolts, a 7.50″ used in late 70s and 80s cars, and a 8.875″ unit used in trucks. So when presented by someone selling you a 10 bolt gearset, be very careful about what you’re buying.
Don’t forget to correct your speedo gear, whatever choice you make.
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Content last modified: January 22, 2014 at 9:33 am
Q: Limited slip vs. Positraction vs. Safe-T-Track
What is the difference berween a limited slip rear end and a posi? Or are they one and the same? If they are different, were they both available in 1st gen birds? How do you tell the difference.
A: It’s my understanding (someone please correct me if I’m wrong) that they are one and the same. Dealer literature called them “limited slip” while the users called them “posi”. If could also have been the used by two different car builders (i.e., Pontiac/GM called them limited slip while Chrysler called them posi-traction). That’s my guess.
A: There isn’t any difference. Each GM division had its own name for it, and probably a slight variation on the design too. Pontiac’s was actually called Safe-T-Track, Chevy was Positraction, they are both “limited slip” type rear ends.
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Content last modified: January 22, 2014 at 9:34 am
Q: Safe-T-Track Clicking
I just installed a 3.23:1 safe-t-track (2-pinion) carrier into my firebird. The backlash is about .008″ and the pattern looks good. No howling at any speed. The problem is when I was pulling into my garage (tight right turn) that I noticed this “clicking” sound coming from my drivers side rear tire/axle.
Is this normal? Are the spider gears/cones disengaging as I make a slow turn? At higher speed turns (+15-20) I do not notice it. The center section was rebuilt with new machined and shimmed cone seats. It is very tight. Any old school mechanics out there? Thanks in advance.
A: Mine does it. The posi unit might be worn. I think the nosie comes from when one of the cone slips and then this sudden slip is translates to you drive shaft making a tinging noise. My friend 78 Z28 did the same thing. Check your transmission output shaft bushing too. If its a 4 speed car the bushing only last about 40,000 miles under hard use.
A: This is pretty common on GM posi units. If you add 2 bottles of GM posi additive( use GM not brand X) and it still does it , try changing the gear oil and add 2 more. You must do some sharp right and left turns, back up etc to get the additive circulated real good before giving up and changing lube again.
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Content last modified: January 22, 2014 at 9:36 am
Q: Possi. Traction Rear End 1967
I have a question that no one out here seems to be able to answer! Did the 1967 Firebird come stock with a 323 possi. traction rear end with traction bar brackets and tortion bar eyes on the top of the punkin? If so were these able to fit a 68? The reason is from backing plate to backing plate is the same length as on my 68? Why are there eyes on the punkin? Thanks for any information you can give me?
A: I think I can answer questions on rear ends. All 67s had the eyelets on top of pumpkin because they used the A body rear (Tempest,GTO) 1967. Cars that had traction bars were any that had a Heavy duty rear end whether it was 326 HO or 400. I have had several 1967 Sprints with traction bar rears. As a matter of fact ALL Sprint Firebirds for 1967 came with factory traction bars. These could be adapted to the 1968 but then I pose the question WHY… with staggered shocks and multileaf springs the 1968 was a better setup. just try going over a washboard road and youll experience this. All posis were an extra cost item, until the Trans AM. Some models it was required tho. On the trim #s I think John boo booed and that was 250 and 270 dk. blue standard buckets and dk.blue bench.
A: There has been a ton of speculation on this issue, but no one has ever come down with an authoriatative answer. However, it has been my experience that as a rule, Firebirds with open rear-ends got one traction bar on the right, while cars with limited-slip rear ends got traction bars on both the right and left.
IF there were, (and that is a big IF), cars which had none, I’d bet it had to do with the ring and pinion ratio. The rear end codes on the third members were independent of the engine/trans installed in the car.It is my guess the traction bars were an after thought to make up for excessive wheel hop due to the mono-leaf springs.
A: I have a 1967 that came with sprint 6 and it has both traction bars…hope this helps …
A: In the past, there have been a couple of threads concerning the factory traction bars on 1967 Firebirds, in particuliar, the rules governing the hows & whys of whether you got none, one or two of them.
While researching differentials and available axle ratios, I came across what I believe is the definitive answer to those discussions. In the Firebird supplement to the 1967 Pontiac Service Manual, it has a section on the rear suspension, propeler shaft and differential. (Section 4 for those who have a copy of this supplement). First, these tranction bars are refered to as Radius Rods in the supplement. Here is the chart, (reproduced here in ascii text), which shows how many radius rods were on the car, based on engine size, transmission type, and in one case, axle ratio:
RADIUS RODS USED | 6-cyl. 1-Bbl. | 6-cyl. 4-Bbl. | V-8 2 / 4 Bbl. |
---|---|---|---|
None | *Auto Trans. | ||
One on R.H. Side | Man. Trans. | Auto Trans. | Auto Trans. |
Two | Man. Trans. | Man. Trans. |
*One rod is used if ratio is 3.23:1
I hope this information sheds some informative light on the subject.
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Content last modified: January 26, 2014 at 4:30 pm
Q: Saf-T-Track Axle on Ram Air
Was the Saf-T-Track Axle part of the Ram Air package?
A: …According to 1967-1968 Firebird Sales Literature, when you ordered the Ram Air engine, it was mandatory to get code 361 (Saf-T-Track Axle). However, I don’t see this prerequisite for 1969 on either the Trans Am or 400 H.O. option (with or w/o the Ram Air Hood Option). So, if your documentation does not show code 361 Saf-T-Track then that’s how it is in 1969. 🙂 Anyone have something that says otherwise ?
A: T/As came standard with posi rears ,all 1969 T/As had R/A engines . other items were of course… variable ratio p/s,power discs,1″sway bar etc.
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Content last modified: January 22, 2014 at 10:01 am
Q: Rearend Swap 1967
Does anybody know if a 1969 Lemans rearend will fit in a 1967 Firebird?? Any modifications needed?
A: A body cars use _coil_ springs in the rear, whereas F bodies use leaf springs.
The A body housing will be wider than the stock Firebird piece, and will require narrowing, or special offset wheels. You can cut off the perches and mounts from the Lemans rear, and weld on perches for the leaf springs. But this is a lot of bother for a 10 bolt.
I’ve read that some 1st gen owners use the 2nd gen rear, which is a bit stronger. But this rear is still wider than your 1967 rear. I don’t know how much wider, or if the spring perches have the correct spacing.
A: I just bought a 1977 Firebird 3.23 Posi (Code PX) Rear for a 1969 Firebird. I too was told that these are wider than the 1st gen rears. However, I have measured both rears, more than once, and in more than one way, and could not find any difference in the OVERALL width.
Since I had heard so much of this “the 2nd gen rears are wider” stuff I still couldn’t believe my measurements so I checked my AMA spec for Track Width Rear and the number is 60 inches, same goes for 1968’s. I didn’t have a 2nd gen spec but thankfully one of you on this list did and guess what? The number is 60 inches for 6″ rims and 60.3 for 7 inch rims. I’m now convinced that the 2nd gen rears are NOT wider. I’d be glad to hear anyone else’s 1st hand experience.
As far as the Spring “perch” or mount that is welded onto the axle tube, they ARE indeed wider on the 2nd Gen by about 2 3/4 inches. I will have to have these cut and re-welded.
Last thing, 1968-1969’s and 2nd Gen’s all used multi-leaf springs so if you get a 2nd gen rear for a 1967 you’ll either have to convert to multi-leaf of use “perches” from your old rear because the depth is different.
A: I have used a 2nd generation rearend in a 1968. It’s only about 1/2 wider on each side. The existing spring perches must be removed and new one welded closer to the differential. Care should be taken to properly align the pinion angle. The drive shaft will have to be shortened. If you use a rearend from a 400 transmission car you’ll need a big-and-little U-joint as well. Aside from the cost of the rearend itself, The costs were as follows: new perches $25; drive shaft work $35; U-joint $18. Good luck.
A: I’ve got a gto rear in my 1967. had to add spring perches, and clean up the coil spring stuff. not many 12 bolt rears around, so its worth the work for a 12 bolt.
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Content last modified: January 22, 2014 at 10:02 am
Q: Rearend Swap 1968
Does anybody know the particulars on swapping a second gen. rear end in to a first gen firebird? I have heard that the second gen. is wider but not by much and that you have to cut off the spring mounts and weld on new spring mounts. Any first hand knowledge out there?
A: The swap you are researching is rather straight forward. I completed a successful swap of this type on a 1968 Camaro. The posi was a lot cheaper and the breaks are the same. Some things you’ll have to do or look out for:
-You will have to relocate the spring perches. either cut these off of the old rear end or by some weld in units from your local speed shop. – When choosing a rear end, look for a transmission match (i.e., if you have a power glide or 350 turbo, get rear from a 350 turbo car or 400 turbo from a 400 turbo car. 350 and 400 turbo use a different size U-joint. -Be sure to match the pinion angle of the old rear end with the new (i.e., the relation of the pinion angle to the pads is critical fro long life. – You’ll may also have to shorten your drive shaft.
A: First, why would you want to put a 2nd Gen Rear in a 1st Gen Car? Well, they’re more readily available, which also means cheaper.On top of that, the 8.5 inch rear is much stronger than 8.2 inch. Of course, there are some mods you’ll have to do so that’s something you have to weigh out to see whether it’s worth it to you.
Now for some short disclaimers. The car I was putting the Rear into was a 1969 Firebird which originally had a 2.56 open Rear and multi-leaf springs. The new Rear was a PX code 3.23 Posi with a casting date of C187, from a 1977 car. I know there are some minor difference between the early 2nd Gen cars (1970-1975 or 76) and the later ones (1976 or 77-1981) with respect to U-Joints and Brake parts so I can’t be sure that everything that worked on mine will work on yours.
Here we go…..
OVERALL WIDTH – I had read many times that the 2nd Gen Rears were anywhere from 1-2 inches wider overall than the 1st Gen Rears. Well, I took many, many measurements to be sure I wasn’t fooling myself and found that the 2nd Gen Rear is only 1/4 inch wider overall (1/8 per side) than the 1st Gen. This measurement was taken on the outside of the ends of the axles where the lugs are pressed in.
MULTI VS MONO LEAF – As I understand it 1967 models will have mono-leaf springs. 1968-1981 are all multi-leaf. I don’t know too much about mono to multi leaf conversion, I’m going to assume that you are swapping into a 68-69 car. If you want to put one in a 1967 car, I would guess you’ll either have to use your original mono-leaf mounts/perches or convert to multi-leaf. Let’s just say that you will have to work out all those further complications.
SPRING MOUNTS (OR PERCHES) – There are some very important things to remember here. First, if you haven’t figured it out yet, the 2nd Gen mounts are much further out (about 2 3/4 inches) from the center than the 1st Gen mounts, you will have to cut them off and weld different ones on. Why not just re-weld the ones you cut off, but in the new location? Well, the first gen mounts have a built in angle such that the springs are further apart at the rear of the car (by the shackles) than at the front. The 2nd Gen does NOT have this angle. I didn’t know this and simply cut and moved the mounts on the 2nd Gen Rear. It turned out there was enough play between the spring and the mount that I could still cock them a little and they would fit but I would recommend to anyone doing this to either cut and use your old 1st Gen mounts or get a set from another 1st Gen Rear end. Another good reason to do this is that the 2nd Gen mount is about 1/2 inch “taller” than the 1st gen which lowers the spring (and the car) off the axle by that extra 1/2 inch. The last thing you should take care about is the pinion angle. This is the angle between the Rear End pinion and the drive shaft. If you screw up the mounting of the perches you will mess this up. I took measurements of the angle between the pinion and the spring mounts on both Rears and found them to be the same, so I just cut off one perch and moved it to it’s new location (you should be using a new perch here), made sure it was level with the other one, and re-welded it. A different (or better) way would be to place the Rear under the car and put the car’s weight on the springs. Then set the angle to what you want it and tack weld the spring mount. Remove the rear and finish the welding. I couldn’t do it this way because I didn’t have any welding tools and the car was in my garage. By the way, this didn’t cost me anything because I did the cutting and welding at a friends house, but it did take a few hours. MAKE SURE you have your measurements correct, you don’t want to have to do this twice!
AXLE REMOVAL – You will have to remove the axles and break backing plates to be able to cut the mounts very well. Be sure to understand how to do this before you start, it’s pretty easy.
BRAKES – The brakes parts are pretty much the same for both. I bought all the new brakes parts by asking for the 1977 parts, used the 1977 backing plates and drums. As far as brake lines, if you are getting new ones, buy the ones for the original 1st gen year. This way you don’t have to re-route the line coming back from the front of the car. On mine there was a bracket that mounts to the top rear end cover bolt. This holds the fitting at the end of the flexible hose that the two brake lines thread into. Make sure you get this off the old rear and put it on the new one BEFORE you get the rear up under the car or it might be hard to put on. Plus you’d hate to have to remove a cover bolt after you have your gasket sealed well.
SEALS and BEARINGS – Seals are cheap, so replace them. Don’t buy them from the repro companies, they charge a lot. Get a decent brand from a local parts store, they should only be about $1-$2 a piece. As far as bearing, they are more difficult to replace and more expensive but you should at least check the old ones for wear and replace if necessary.
AXLE to U-JOINT DISTANCE – By my measurements the 2nd gen rear is longer from the axle to the u-joint mount by 1 inch. Unless you have a lot of play up at the transmission end, you will need to have your drive shaft shortened or fabricate a new one. While you’re at it, replace the u-joints if they’re still the original 30 year old ones. My cost $65 for cut, balance, and install 2 u-joints. They wanted about $125-$150 to fabricate a new shaft from scratch. While you have the drive shaft out, why not replace the output shaft seal on the trans too, again very cheap. Oh, and I was able to get my driveshaft out without removing either exhaust pipe but you might not be so lucky, be prepared to have to unbolt one at the manifold or header in order to get the drive shaft out.
U-JOINTS – Make sure when you get the Rear, you get the hardware to strap the U-Joint to the Rear End. The hardware was different on the two Rears for my swap. It may be the same for you but it’s better to have it to be sure. Also, depending on the donor car you may need to get a “Big/Little” U-Joint to adapt pontiac type to Chevy type.
SPEEDO – If you changed ratios you’ll need to recalibrate you’re speedo, I know you already know this but for some good info about doing this with Auto Trans try http://www.classicalpontiac.com, go to the Q and A, go to Archive #5, and look at Topic #1162. By the way, I haven’t done this yet. It’s weird to cruise to work at 90 MPH…
GAS TANK – Probably a good idea to remove the gas tank as a precaution. Definitely do this if you are also replacing the springs as you will probably need to use a torch or grinder to remove some bolts! While you have it out, why not clean it out and get it painted nice. I found all sorts of junk in mine…yuk!
SPRINGS – As far as leaf spring replacement goes, just a few comments. If they’ve been on for 30 years you WILL need to cut or torch the bolts off. (Again, remove the gas tank!) Even then the rubber bushing are a pain to get out, be patient. You will probably also have to scrape the rust out of the body slot before you will fit the new bushings in. Also see “Parts To Buy” below.
PARTS TO BUY – I’d recommend having the following new parts ready when you start:
- FOR THE REAR END
-
—————
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Seals
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Bearings (If You Choose)
-
Brake Lines
-
Brake Parts
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New Posi Tag
-
Gear Oil and Limited Slip Additive
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Cover Gasket
-
Housing to Break Backing Plate Bolts/Nuts (if you break ’em)
- FOR THE SWAP
-
—————
-
U-Bolts and Nuts (May Break ’em)
-
T-Bolts and Nuts (May Break ’em)
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Upper and Lower Pads
-
Trans Output Shaft Seal
- FOR NEW SPRINGS
-
—————
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Front Eye Bushings (If they don’t come with the springs)
-
Front Bracket Bolts and Clip Nuts
-
AMES carries these, others only have the clip nuts
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If these haven’t been replaced very recently,
-
you will probably break the clip nuts
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Front Eye Bushing Bolt/Nut
-
Shackles/Bolts/Nuts
-
Rear Shackle Bushings
- GAS TANK
-
—————
-
Tank Straps
-
Attaching Bolt Kit
-
Tank to Body “Anti-Squeak” Kit
Hope this turns out to be helpful to someone. Good Luck. And if anyone else does this swap and has some feedback, let me know.
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Content last modified: January 22, 2014 at 10:04 am
Q: Rear End Swap
A: Classical Pontiac a good reference sheet in their restoration section on putting a second generation diff into a first generation. There are some mods to be made, but it is possible, and I think worthwhile. I am planning on replacing my 256 open diff with a 373 posi unit from a 74 f body. I am counting on the info from that site to be accurate, and the change to be not too difficult
A: I did this swap this last summer, and in reading Geebgens report, posted both on his own website:
http://www.angelfire.com/on/geebjen/rearswap.html
(geebjen is a member of this list and has an excellent site with tons of useful info)
…and on the Classical Pontiac site:
http://www.classicalpontiac.com/
(click the restoration link)
…I found that it is pretty much spot on with the description of the rear swap. The only thing I could add to this would be that I found that I needed to keep the parking brake cables and the approriate bracket from the 1st gen. rear end. The 2nd gen cables wouldn’t work.
Pricing varies from area to area. I paid $75.00 to get the spring perches done. I didn’t realize until too late that they had used a generic perch that required 2 ubolts per axle, compared to the single ubolt that is stock. The original perch has a pocket or recessed area for the spring to seat, while the replacement perch is flat.
Another gotchya was that they welded the perches about 1/2 to 1″ too far apart. I had to muscle the springs into place, and this placed the shock mount in contact with my passenger side wheel rim.
My rear wheels are 8″ wide, w/ 4.74″ back spacing.
I also paid $110 to have my drive shaft shortened and balanced.
Check the ratio on any second gen. rear you think about buying. While 3.23 and 3.42 ratios are fairly common, you can still run into Posi rears with 2.73 and taller gears. Not optimal ratios.
A: I made this swap last winter and found out that replacing the perches was not necessary. The first gen. perches are slightly angled versus the second gen. which is straight. The leaf springs are further apart in one end than the other on our cars. Still the sec gen. perch is wide enough to accommodate the angled springs. Therefore I just grind the perches off the sec gen. rear end and moved them closer together. I did not buy any new perches and I did not remove the old perches from the original rear end. Only thing to remember is the sec gen. perches are about 10 mm higher which LOWERS your car by the same amount. ( oh sorry, 3/8″ )
How to get the correct position: I took lots and lots of measurements of the rear ends and also the distance between the leaf springs under the car. I then drilled two holes with the correct distance in a wood plank and bolted the front spring brackets to it. When I had this assembly (springs, plank, perches) clamped to the rear end with the U-bolts I could measure that everything was correct and weld the perches.
The only parameter I couldn’t measure and had to use my eye was the angle of the yoke to the horizontal plane. The only way to do this in a better way, that I can think of, is to have the rear end mounted in the car with the prop shaft attached and weld the perches in place when the cars weight is on the springs.
Regarding prop shaft length. Don’t go wasting your money to get it shortened before you have searched your junk yard. You will be surprised how many different lengths there are. I managed to find one that bolted right in.
A: Niklas, your input on the 2nd gen. perches is useful. I’d read in another write-up that the user had not accounted for the perch angle and had a minor problem due to that. If I had it to do over again, I’d probably stick with either the 1st or 2nd gen perches.
Regarding prop shaft length. Don’t go wasting your money to get it shortened before you have searched your junk yard. You will be surprised how many different lengths there are. I managed to find one that bolted right in.
Interesting, though I might add that a junk yard prop. shaft is an unkown factor. After hunting for the right length, yoke and u-joint types, I might still end up with a unit that is either bent (causing severe vibration) or with bad u-joints that could fail shortly after installation. As my car has some modifications that enhance it’s power output, I didn’t want to go too cheap on this critical link. I’ve had 1st hand experience in drive shaft failures, and want to avoid them whenever possible.
The 1st time was when the rear joint in my 1969 Chevelle gave way while driving down Colfax Ave in 1976 in Denver. While resulting in a lot of noise and a loss of power to the rear wheels, I lucked out and coasted to the side of the road. The second time was when I was following some friends at Lake Tahoe in California in 1980. They had piled into thier freshly painted 1968 Camaro Ralley Sport. The front u-joint on the Camaro failed at about 45 mph. The drive shaft dropped to the ground and immediately pole vaulted the Camaro’s rear into the air. The rear axle assembly tore loose from the leaf springs and was thrust up into the fuel tank, spilling gas everywhere.
The occupants got lucky in that the car didn’t end up on it’s roof, and further lucky in that aside from some bad bruises, no one was seriously hurt. That wasn’t the case for the car. Sadly, the wounds were mortal and the car ended up in the junk heap. We salvaged what parts weren’t bent up, and that was the end of that car.
From my perspective, the money I spent on the cutting, balanc- ing, and new joints was a good investment. But I do see your point when trying to keep the budget under control.
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Content last modified: January 22, 2014 at 10:07 am
Q: Ralley II Wheel Code
Does someone know the correct codes for Rally Rims? Specifically, I heard there was a different code for rims on drum versus disc.
A: Check out the following WEB site by Richard Rauch:
Rich’s Pontiac Server http://pontiacserver.com/wheels.html
It is a fairly comprehensive page dedicated to pontiac rims and codes.
A: Parts book published in 1971 says 1967 used JA for disc and JC for drums 68 was JC for all. Try and figure this one out. All the parts for disc were the same for 1967 and 1968 so what made the difference I don’t know. A-body was just as confusing. I have several sets of JA and JC wheels so I m going to measure the offset of both. You can post this info if you want to.
A: The correct Rally II wheels for 1968 Firebirds with Disc Brakes is “JC”. References: 1968 Service Manual, 1968 Parts Book, Broadcast Sheet ((I’ve also verified this and several original, unrestored 1968’s)). At some point, someone started this (JA in 1968) ‘technical error’ while refering to the 1967-1968 GTO and 1967 Firebird.
A: Still dont have a clear idea of why 67s used two different RallyII wheels, one for drums the other for discs. Want to remind everyone that the code is at the valve stem not inside the rim. Ive seen some stamped with JC inside the rim and have a different code at the valve stem.
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Content last modified: January 26, 2014 at 12:10 pm
Q: 8.2 vs 8.5 10 Bolt Rear
What is the difference in the two 10 bolts in ’67? Was the 8.5 the posi? I haven’t been able to find an explanation anywhere.
A: As far as firebirds go, all 1967, 1968, and 1969 firebirds had the 8.2 inch rear end. It has nothing to do with whether or not they were posi. The 8.2 inch rear (at least in firebirds) is considered a BOP rear (Buick-Olds-Pontiac). Starting at least partly in 1970 and then from 1971 on (I think) the firebirds all used the Corporate (Chevy) rear end which is 8.5 inch. Again, nothing to do with whether or not it is posi.
Aside from size of the ring gear, 8.2 inch rears also used a different posi unit (cone-type vs clutch-type) which is considered weaker, they attached somehow at the end of the axle near the bearing (haven’t taken the time to figure exactly how yet) vs the 8.5 which use c-clips inside the carrier, plus other differences.
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Content last modified: January 22, 2014 at 10:09 am
Q: Correct/Original Rally II Rims on 1968
I’m interested in putting Rally IIs on my 1968 (Verdoro Green – a great color) with factory power disk brakes. I understand that only a certain code will fit otherwise the wheel hits the caliper. Ames said it was code J0. Does anyone know this for sure? How hard is it to find them?
A: ..For many years, people and resto guides have been passing around the wrong info when it comes to the Disc Brake Rally II Wheel. For the GTO, the correct code is “JA” For the Firebird however, the code is NOT “JA” but instead, “JC” which is also the same for Drum Brakes. That’s right, you don’t need a special Rally II for Disc Brake Firebirds. Here’s the proof….
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1968 Service Manual lists “JC” as correct for the Disc Brake Rally II
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Broadcast Sheet lists “JC” as correct for ALL Rally II applications
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The Parts Book (dated 1969) lists “JC” as correct for all 1968 Firebird Rally IIs
I’ve inspected several original unrestored 1968 Firebird’s and found “JC” wheels on all of them. There is a different wheel if you had wheel covers. That is “HK” comapared to the standard “HG” rim. I have an original 1968 Firebird that came with Disc Brakes and Rally IIs. The rims I have are all “JC” and I don’t see any clearance problems. Sure, you can pay the extra money for the “JA” wheels but you don’t have to and besides, they’re not even correct. Even the latest “FIREBIRD DECODING GUIDE” by Thomas DeMauro (HPP) lists the wrong code. Infact, they don’t even come close as they list “HK” for the DiscBrake Rally II wheel. So, for 1968 Firebird’s with Disc Brakes, look for the “JC” rim. It’s documented as correct and it’s much cheaper than the “JA” that all these used parts dealers sell thinking it’s the Disc Brake Rim for all 1967 / 1968 Firebirds/GTOs
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Content last modified: January 26, 2014 at 12:13 pm
Q: Drive Shaft Yoke Seal Leaks
Question about the drive shaft yoke that goes into the tail of the trans. Gear oil leaks out the tail of the trans so I replaced the seal. No biggy. What my problem is .. I slid the drive shaft out and you look at the yoke to find that the about an inch of the outter yoke seems to be worn badly.I think this surface should have a machined finish to it. My brother looked at it and seems to think the drive shaft is to long. I drained the oil and didn’t find any big pieces off metal. The magnet on the plug had a finger tip size of sludge and some small fillings on it.
A) Is this normal wear? 30years +
B) Is drive shaft to long? How do you measure?
C) Is it the wrong yoke?
D) Can you cut an inch off the yoke?
A: If the yoke is that worn chances are that a new one isnt going to fix it. I think the inner tailshaft bushing is severly worn. You must remove the tailshaft to remove /and replace this bushing. It is pressed into the housing and is about 2 in long. This is a softer material than the yoke so it is sacrificial.
A: Sounds like normal wear for a 30 year old drive shaft. The yoke can be replaced fairly inexpensively. Your obvious choices are new or used. Check with your local parts dealer or dealer parts counter for the price. The other choice is to check with the local junk-yards for a good used one. The yokes are common to almost any brand of GM car with similar transmission.
As far as length, in the normal weighted condition you should have about 3/4 to 1 1/4 inch sticking out of the tailshaft.
A: Your drive shaft seems to be in pretty normal condition to me. The part of the yoke that sticks out of the tranny always looks pretty bad. The question is what does the yokes surface area look like that is inside the tranny. It should be clean due to constant contact with oil. And most importantly, what does the yoke look like where it comes in contact with the seal. My bet is that the seal has worn into the yoke. Again, that is normal for a 30 year old car. The problem is that if there is too deep a groove from the old seal, a new seal will still leak. I would first replace the seal in the tranny and replace the driveshaft. Sounds like you have already decided to replace the gear oil. Good move! If after new oil and a new seal it still leaks, replace the yoke. Fortunately, none of this work is rocket science, so go for it!
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Content last modified: January 22, 2014 at 10:10 am
Q: Rally II Wheel Fit
Seems I got a pair for 1968 +/-, and a pair from the early 70’s, when GM made the holes smaller. Am I up a creek or is there some way to get caps that match for these things. HELP!!
A: There’s a lot more to Rally II wheels than the responses have indicated. There were probably 30 or 40 varieties of this wheel, likely a half-dozen in just the 14×6 size! The ONLY way to know what you have is check the 2-letter code on the wheel next to the valve stem, and post it here for us to help you. There were also some numbers stamped near the valve, but these were date codes. The larger center hole is a non-issue (the caps will fit), but you need to make sure of wheel offsets. Some later 14×6 wheels were used on Ventura II’s, the Nova body clone of 71-74 including the last year of the GTO. They have different offsets than the correct wheels for your car. Even in 1968 alone, there was the JC code for Firebirds, and a JA code for Tempest/LeMans/GTO. The later 71-74 wheels were coded something with N or M as the second letter, I can’t remember if there was an HN/HM or something else. I know there were HF wheels I have that are 15×7 with a 4-3/4″ bolt pattern used on the A and G body cars from 73-77. Speaking of 15 inch wheels, there were also 15×6 and 15×7 for full-sized cars with a 5 inch wheel stud pattern! I even know of 4 different 14×7 wheels with different sized center holes that all have the same offset, from the JK code for 1969 Firebird and Grand Prix, JM for 70 same cars except Trans Am, JS for 71 and KS for 72. The 70 Trans Am had a special wheel, looked like a center section from a 14 inch wheel, with a deep-dropped center 15 inch rim, that would not accept any trim rings (Olds did something similar in 75 that had a ring that would retro-fit).
A: Thanks for response. I went and checked, I’ll give you the codes both inside and out. Here goes; one wheel has JC outside and JJ inside. The next has KT out and JK in. Then, JA out and JK in. The last has HN out and JK in. Now as for offsets, if I remember correctly, the offset is measured on the inside of the rim, from the inside edge down to the bolt holes. I checked this with a straight edge across the inside rim, then measured down to the holes vertically. After checking this, I found 2 of the rims measured 4 inches and the other 2 measured 4 1/4 inches. Man what a mess this is turning into. Didn’t have clue as to how many variations there were. If I measured correctly, how do I know if I can use them or not, now that I know that the caps will fit? Or do I have to go to the car, pull a rim, and measure the drum? All I’m sure of is that the drums are stock.
A: Guys, I would suggest we all get on the SAME PAGE!!! The code NEXT to the VALVE STEM is the one the parts book uses! The code on the INSIDE is the RIM type, but the one OUTSIDE is the WHEEL CODE for the ENTIRE WHEEL assembly!! That means the RIM, the CENTER and the OFFSET! Please stick with the WHEEL CODE on the outside, and ignore the RIM type!
A: Yup, Rally wheels seem so simple at first.
But that 1/4″ width isn’t really a big deal.
About the only time you need to worry about brake clearance is with disk brakes, and even then many of the 14″ variants clear those.
You are safe with backspacing varying from 4″ to 4.5″, as long as you don’t go crazy with tire sizes. And since these are only 14×6, you are limited there anyway to nothing much wider than a 225/60-14. That tire, on that wheel, should fit your car. A 215/60-14 might fit the wheel a bit better, and that will definately not have clearance problems with your car, even with that rear sag you mentioned earlier, but may appear a bit short. Going to a 70 series would get you taller tires, that might fit that narrow wheel better.
Key Words: Ralley II, Rally II, Rallye II, Wheel Codes, Rim Date Codes
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Content last modified: February 24, 2014 at 10:07 am
Q: Rear Seal Replacement
I intend to replace the rope rear main seal in my 1968, 350, with an original type rope seal. All the information I could find on the cheveron/lip type Cadillac seal required pulling the engine and crankshaft to properly install it.
The engine is still in the car and at this time that is where I would like it to stay. My question: Is it possible to drop the pan with the engine in place? I am worried that there may not be enough clearance between the front crossmember and the pan to allow the pan to clear the crankshaft and be removed.
If so are there any tips or procedures that make this possible or easier? The bellhousing and flywheel are removed at this time.
Any advice would be appreciated.
A: The rear seal (upper half) can be changed without dropping the crank by using the new seal and turn the crank by hand. The seal can be rotated out of it’s position, and the new rotated in. But, the hassle you’ll have just getting the pan off isn’t worth it. It’s best to pull the engine and do it right. With the engine out, it’s a lot easier and you can do some other things while you’re in there. Like change all the bearings. These can also be turned out by using a bent cotter pin. Just bend the cotter pin to look like a “T” and put the bottom of the “T” into the oil journal. Then, you can turn the crank and the bearing will turn out with it. Put the new one in this same way. This way you don’t have to remove the crank. Just remember to use engine build lube. This is also a good time to replace that 30 year old oil pump, the heart of your engine (it stops, you stop). I’ve tried removing the pan and doing this on a Camaro with a 350, and I had to drop the steering idler arm, and lift the engine a couple inches just to get the pan off. Even then, things were tight and made changing parts very hard. I finally pulled the engine and finished it right.
A: I can tell you this much…. Yanking the engine at this point would be pretty simple… especially if you can easily disconnect the exhaust system. My guess is that you can yank the engine with about 4 hours of work and two sets of hands at this point. Swapping the seal once the engine is out is only an hour or two (plus whatever else you want to do). If you do it, keep in mind that you can also reinstall your clutch with the engine out and avoid the pain in the butt of remounting and aligning the clutch assembly from the underside of the car. All said, you’re probably about even, or ahead time wise (removing the engine vs not removing the engine)….. And that assumes that you would have had no problems if you did all the work from the underside. If you consider the skinned knuckles, oil in your hair and @#!%$@@ words that go with under car work, I would certainly remove the engine…. But that’s just me. Now that I’m a member of the 40+ gang, (who has false teeth do to hitting himself with a misguided wrench) I try to stay on the top side of the car as much as possible.
A: would go one step further. replace your rod and main bearings along with the oil pump while you have it down. It has been my experience that seals dont start leaking for no reason ….. there is wear there that is allowing the componemt to move and cause the seal to leak.
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Content last modified: January 22, 2014 at 10:11 am
Q: Wheel and Rim Compatibility
I am planning on buying 15X8 wheels with a 4″ backspace. I would like to go with 225’s up front and 275’s out back. Will this work without body modifications? Anyone currently running this setup? I have seen 275’s on 1st gen camaros, but never had a chance to talk to the owner.
A: It would be helpful to know if you’re talking about 60 or 50 series tires. This would greatly affect the fit question.
1st issue, the wheel. The factory 14×7 and 15×7 typically have a 4″ backspacing. If you keep the back spacing the same, but make the tire and wheel wider, most of that new width goes to the outside. 4.5 inch backspacing on an 8 inch wheel would distribute the new width equally to the inside and outside. In measuring my car (’68), I found that I had room for 5″ backspacing on an 8 inch wheel. This allowed me to fit a 265/50R-15, and not have it stick out of the wheel well.
Now for tire sizes… If you are talking about 50 series tires, a 275/50-15 would most certainly protrude beyond the wheel opening. That tire will be about 10.82 inches wide, and will most likely be sticking out about an inch. If you use this tire and wheel combo, you will have to raise the car high enough to clear this tire, but it’s up to you to decide it that looks good to you.
Where the 50 or 60 series issue come up is related to the tire height. A 275/50-15 about 25.8 inches tall, a 275/60- 15 will be about 28 inches tall! You’re going to have to lift the rear of this car alot to clear a 28 inch tire.
Check the inside of your wheel well. The potential con- tact areas will be… the top inside area of the inner wheel house, The leaf spring, and then the lower shock mount are the moste likely places where it might rub.
I would suggest the following steps.
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Remove your present wheel and tire, and measure the backspacing.
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But the tire and wheel back on the car. Now measure the amount of clearance you have, both on the inside and the outside. Allow at least half an inch for side to side movement of the axle, plus a margin for up and down movement, and then you can determine how much larger than your present tire you can fit. Pay attention to where you want the wheel/tire center- line, and what backspacing is needed to make it fit.
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The end result will be that you will know that you can go x inches wider than present, but need y inches of backspacing to make it work.
A: Why do all this measuring? I could tell you that you could fit tire size x on wheel y. This would work for a smaller tire, with much larger margins for error. But when you get into the big stuff, you have less room for mistakes. Each car is somewhat different, and the clearances onmy car may not be the same as yours.
Q: Rubbing and Fit
You mentioned that you were running a five inch backspacing on a 15 inch rim with a 265/50-15 on the rear of your 1968. Did they rub or hit at all (over big bumps, etc.)? I assume that you did not modify your rear suspension and that your springs were in good shape. Right?
If this combination gave you trouble free performance, I would love to see a picture to help get an idea of the appearance. Also, what are you running up front
A: The car got about 800 to 900 miles usage before going dormant to get the interior sorted out. That included about 700 miles of highway driving (trip to Reno), and the rest was low speed cruising on various road conditions. We did a lot of driving in and out of various driveways and parking lots that were off camber or had steep drives.
The rear suspension consists of all new parts including 5 leaf springs, KYB shocks, bushings, and shackles. No rubbing or hitting in the rear was noticed.The parts are all stock re- placements.
Presently the rear sits a bit high by my preferences, about 3 inches above the tire. I hope that the springs will settle. If not, I’ll have to remove a leaf to adjust the ride height. No problems with the ride being too stiff or harsh.
I was running 225/60R-14s on 14×7 ralleys, which were in rough shape (the wheels). I have since changed to 225/60R-15s on 15×7 Ralley IIs. The front tires would occasionally hit the inside of the wheel wells when I drove to quickly into a driveway. The front springs have had 1 coil removed to get the nose down.
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Content last modified: January 26, 2014 at 12:24 pm
Q: Thumping at Low Speeds
I have had a problem with thumping noise coming from the rear passenger side of the car since i got it. I have replaced the bearings and no difference. What could this be. The sound dissappears at high speed (or just becomes one noise) so I am pretty sure it has something to due with the tire. ITs new and the same size all aroud. Could it be out of balance?
A:
1-Check for broken spring
2-check for loose or broken U-bolts
3-Check and replace U-joints
4-This you do not want to read , worn carrier bearings causing the pinion and ring gear teeth to hit , but at high speeds the carrier goes back into place .
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Content last modified: January 22, 2014 at 10:12 am
Q: Rally II Rims 1967
Is the JA code ok for 1967 firebirds?
A: I believe the offset is inward either 1/8″ or 1/4″ per wheel, and will narrow the tracking of your Firebird. You would be better off finding a Tempest/LeMans/GTO guy who is desperate for those JA’s, and find yourself the correct JC code wheels for restoration. Unless of course you want to go to 7 inch wheels!
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Content last modified: January 26, 2014 at 12:42 pm
Q: Bleeding Brakes
Speaking of bench bleeding….. how is this done? Is there some books that explain this that I could look at… Or is it simple enough on a 1968 Firebird for a quick explanation here??
A:
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Secure the master cylinder in a level position (level is VERY important).
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Attach a tube to each brake line on the master cylinder and place the other end of each tube in it’s associated well.
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Fill each well in the master cylinder with fresh brake fluid.
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Using an appropriate tool drive the plundger (brake peddle rod) into the master cylinder.
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Continue #4 until no more bubbles appear.
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Plug brake line connectors and put master cylinder lid on.
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Content last modified: January 22, 2014 at 11:45 pm
Q: Rally Wheel Restoration
A couple of years ago I bought a set of 14’s and a set of 15’s from a local guy that advertised in the paper for $20.00 a piece. Yesterday I pulled out one of the 15’s and spent about half an hour at the sand blaster and barely made a dent on removing the old paint.
A: Heres how I clean up Rally wheels. Friends will pay testament to this as I’ve had as many as 30 at a time being stripped and derusted on an assemblyline .
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Buy 2 new plastic garbage cans with a bottom thats a little larger than the wheels youll be stripping.
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Go to the local pool supply place and get a couple gallons of muriatic acid. Be sure and get the industrial strength stuff.
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Go to Home depot and get the spray on paint remover (brush on stuff wont get into the cracks as good)
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Be sure and use a pair of goggles,long rubber gloves and an apron for all stripping and derusting.
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Place the wheel in garbage can and spray with the paint remover, turn over and do the backside and inner part of rim. Leaving the rims inside the cans will contain the spray and concentrate the fumes which help to soften the paint. You can do as many as 3 wheels in the can at the same time.
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Remove wheels when paint is bubbled and pressure wash clean Remember that paint stripper is still active and will burn skin it contacts.
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Once the wheels are clean move them to the second “tank” which has the muriatic acid and water solution.
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Submerge the wheel completely in solution and soak just long enough to dissolve any rust. DO NOT LEAVE IN SOLUTION MORE THAN 2 HOURS Any rust thats not dissolved in this time is probably too heavy for a nice wheel anyway.
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Immediately after removing from solution pressure wash and put in a clean can to mist a coat of OSPHO or similar etch and derust converter.
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Remove OSHPO after a few minutes not allowing it to dry before removing.
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Dry off wheels with compressed air paying close attention to the crack that the rim and center are joined at. Solution if not properly removed will creep out while painting.
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You can then store wheels for later painting or paint the next day after you know they are completely dry.
I did some wheels several years ago and are still bare and showing no signs of rust. The trash cans should be drained into proper containers and disposed of properly. With 3 cans you can do several wheels at the same time and in a days time can do about 5 or 6 sets. IVe also made some mask kits from vinyl that can be reused several times for about the same price as the ones others sell made of masking tape.
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Content last modified: January 26, 2014 at 12:43 pm
Q: 15×7 Rally Rims
I’ve decided to take the step up to 15″ rims to improve handling, but so far I’ve only found two wheels 15×7″ Figure these wheels will be perfect for my rear end. But what should I buy for the front? The junkyard has got 14×6 and 14×7. Did the car have 7 inch wheels as original or will it look to wide?
A: For safe operation, a tire should neither interfere with the control arms or the frame on the inside of the wheel well, nor should it contact the lip of the wheelwell opening, even at full compression of the suspension. Some people like the narrow tire stock look, and others prefer something wider, perhaps much wider.
What fits your car depends on some variables. You might think that it is stock height becuase you haven’t changed the springs, but age and wear can cause a car to settle to a lower ride height. Or perhaps you or a previous owner have lowered/raised the car? Maybe in an old accident the front subframe was bent slightly out of square, so the wheel hubs are slightly out of place in the wheel wells. Or due to age, variation in mfg, the wheel well openings are narrower/wider by .5″ or so.
You should be able to run 15×7 wheels in front as well, but be careful of your front tire choice. 235/60-15 might rub at full lock. Or they might not. These cars came with 14×6 and perhaps even 14×7 wheels as an option. Many of us have successfully run 15×7 or even 16×7 wheels. Some may even be running 8″ wide wheels (as I am, in the rear). Wheel offset and tire size get more critical the larger you go.
Take some measurements and check it out. Measure the backspacing on your 15×7″ wheel. This taken by laying the wheel face down, and laying a straight edge across the back rim. At the middle, measure the depth to the rear face of the wheel center section where it would bolt to the brake hub. This measurement is you back spacing. Then with the front wheel still off the car, put a straight edge on the hub, with the weight of the car resting on a jack sitting under the front control arm.
If you have a tire that is say, 26.1″ tall (235/60R15), the radius of that is 13.05″. If the tire has a 9″ section width, and the wheel has a 4″ backspacing, you need clearance at least 5.5″. Allow another .25″ to .50″ for deflection. Tape a 9″ piece of cardboard to your straight edge, looking like a letter “T”. The top of the T should be offset to reflect your backspacing. Now rotate that T so that you see where it might interfere with any part of the frame, suspension, or wheel opening. Turn your steer- ing wheel to full lock in both directions and measure again. Re- member that as the suspension moves, so will the wheel. Allow for that movement in your measurements as well.
This technique will give you some idea of what tire options will fit your particular car, given the wheels available to you. Sorry for the overly long reply, but perhaps this will enable you and others to figure out for yourselves what will fit, and what choices you have. Plus, many of us will tolerate a lot more changes from stock than others.
Rebuilt Ralley II wheels are available from Wheel Vintiques in a variety of offsets, and sizes. From 14×6 to 15×10. Custom offsets are also available. These wheels use old center sections welded to new rims, and then powder coated and painted in the orginal pattern. The also sell trim rings, center caps, and lugnuts. Pricing through Summit Racing or Jegs is just a little better than buying direct from the mfg.
Wheel Vintiques
5468 E. Lamona
Fresno, CA. 93727 (USA)
209-251-6957
fax 209-251-1620
Summit Racing 1-800-230-3030
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Content last modified: January 26, 2014 at 12:46 pm
Q: Bleeding Brakes
I cannot get these breaks to blIeed on my 69. The car has factory power disc breaks. I had a problem with the power booster it had an air leak. The breaks worked fine you just had to push hard. I replace the booster and master cylinder with one I purchased from NPD. I bleed the breaks into canister with fluid in it I pumped several times on each wheel I also cracked the lines on the master cylinder but still the pedal goes to the floor any ideas
A: Did you “bench bleed” the master cylinder first?
A: If there are no leaks anywhere in the system, and you’re sure there is no air, the only other possibility is that the master cylinder is not right. You can test it by putting plugs in the holes for the brake lines (I thinks bleeders will fit) and pressing on the pedal. If it goes to the floor, the fluid is getting around the seals in the cylinder.
A: There is a button on the secondary delay valve under a rubber boot, it has to be held down during he whole process of bleeding. C-clamp, a wedge of wood, a door stopper something like that will work. It’s the valve that has a single in and out and is barrel shaped, not the distribution block.
A: Thanks a lot guys. I checked the master cylinder and even though it was new it was the problem. Put the old one back on wow I know how to bleed breaks again.
A: The shaft that protudes from the secondary metering valve (under the rubber cap)is often worn and corroded. Removing it, cleanin it up, or just messing with it will often cause the shaft to suck air when attempting to bleed the brakes. This valve is no longer available.
On my recent rebuild I had to replace the valve with the later edition “combination valve” for the disk front, drum rear. It can be purchased from Classic Performance.com or Year One for around $60. You will have to fabricate a bracket for it. Master Power Brake may be able to supply the valve with the bracket but they are spendy.
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Content last modified: January 22, 2014 at 11:49 pm
Q: Ralley II Wheel Paint Codes
I was going through some archived digests from the Firebird L page and noticed a question regarding paint codes for Rally II’s. I have a 1967 convertible and was wondering the same thing. By chance did you get any answers you’d be willing to share?
A: Yes, I did get the paint code information and I would be happy to share it with you. I have redone my rims using these paint codes and they are a dead-on match for the original colors. You will want to get the paint in laquer, not enamel. The finish from the factory was not all that shiney and the laquer finish is a perfect match.
Here are those paint codes:
Section | Color | Color Code |
---|---|---|
Front (outer rim & spokes) | Ditzler Non-smudge Aluminum | #DDL-8568 |
Front (center) | Ditzler Wheel Cover Charcoal | #DDL-32947 |
Rear | Ditzler mixing formula |
#475 6 Units #490 106 Units #400 272 Units #487 442 Units #415 447 Units #476 457 Units #491 477 Units #495 497 Units #499 1000 Units |
Rear (Alternate): (This color is a close match) |
Ditzler 1977 Ford Dove Gray | #2847 |
I used all three of these colors on my rims and compared them to a fifth rim I left untouch. The color match is right on the money. I also used the wheel masking kits from Year One. They made the job of masking the wheels a whole lot easier.
You will want to to paint the back and “rim” portion of the rims first with the gray. Then spray the complete front on the rims with the non-smudge aluminum color. Allow the rims to dry for a few days before you go on to the next step. The final step is to mask off the rims were you want the non-smudge aluminum color to stay, and spray the center portion with the charcoal grey. Once you have sprayed the final coat of charcoal grey, allow the paint to set up but not completely dry. Then pull off your maskings. This will prevent the paint from lifting.
A: These are not Pontiac wheels but this guy shows a decent DIY video and he uses similar colors that we should use:
[youtube=https://www.youtube.com/watch?v=G1k6mONo_iQ&rel=0]
[youtube=https://www.youtube.com/watch?v=xydVCZln6lE&rel=0]
I noted that the guy did not remove the lead wheel weights or the valve stem as he was repainting the wheels with the tires mounted. I highly recommend removing both.
A: I had an issue converting these codes to PPG or at a local Sherwin Williams store. Drop the prefix letters and use the numbers only to convert to their paint codes.
A: Here’s how I supplemented the masks back in 2007:
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Content last modified: February 7, 2014 at 10:29 am
Q: Power Brake Booster
OK…I just spent the weekend discovering that what Classic Industries sold me as a replacement power brake booster for 1967-’70 birds with disc brakes will not fit my 1969 bird with power disc brakes. The rod that connects the brake pedal to the booster is almost exactly two inches longer on the replacement (7.75in vs 5.75in). So I am once again looking for a rebuilt 1969 power disc brake booster or someone who can rebuild the original. Does someone have a solution? Thanks.
A: I had a similar problem with my 1968, this is what I did. I got a piece of thick wall tubing (a piece of pipe basicly) with an ID very close to the rods OD, and cut a 4″ section. I cut the end off of therod about 2 inches from the end. Put the master cylinder and rod-end where they belong with the pipe connecting them, mark it, and weld it all together, both ends of the pipe. It worked well for me, I managed to fit an ’84 Z-28 booster and master cylinder on my 1968 bird. The smaller diamiter booster clears the valve covers nicely.
I know, it’s not factory, but it works good and uses easy to find parts (that I just happen to have laying around).
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Content last modified: January 22, 2014 at 11:50 pm
Q: Trim Rings
What are the correct style trim rings for my Rally II rims? I have seen a couple of versions reproduced.
A: From what I’ve heard and seen, there have been several attempts over the years to reproduce a correct in fit and appearance Trim Ring for the early Rally II applications. (Including some Rally I’s) I do know that the original GM Part discontinued years ago and I’ve seen people asking as much as $500 for a set of (4) of these Trim Rings. (Pt. #9781480). This is the ‘Brushed’ finish. There was a 2nd Type (Pt. #475019) that was the same except it had a ‘Polished’ finish. These were both 4 clip, 14×6 Trim Rings.
As far as reproductions, I’ve seen different versions…. Clip design, outer ridge design, finish and fit are all variations. I’d be interested in hearing from others on this subject and what is currently available.. from who… and how they rate (appearance/fit).
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Content last modified: January 26, 2014 at 12:52 pm
Q: Power Brake Booster Color
I would like to return my power brake booster to its original gold color. I believe that it was cadmium plated at one time. I saw that Classic sells cadmium paint in a spray can … for $75.00 ! The spray paint colors that I’ve seen would make it look pretty tacky. Anybody know of a realistic alternative to getting the gold back into my booster?
A: The booster in fact was cad plated. A silver with a slight gold hue, but not as yellow as some other GM boosters. Check out Jim Matteson’s car for reference. He discusses the booster color in the magazine articles on his car.
http://www.phs-online.com/67bird/
The car was featured in both High Performance Pontiac and Pontiac Enthusuast. I can’t recall in which he discussed the booster.
The spray paint is actually about 5 or 6 cans, and requires several steps to get the results you want. And you may need to experiment to get it right. Still, costly for spray paint. And it’s not cadmium paint, just a cadmium look.
You can get your booster replated. There are a number of places advertised in Hemmings where you can send your booster, where it’ll have to be disassembled for the work. Another choice would be to check the local plating houses in your area. When I bought my booster/master combo from the local brake booster rebuilder, I could specify the color of plating I wanted. He farms the plating work out to a nearby plater.
The cost will be about the same as the spray paint, more if your booster needs rebuilding. The plating will last longer than the spray paint, in my opinion.
A: The process is called yellow cad by some platers, and will vary in shades from plater to plater,or part to part. In other words its not that consistent in the hue and color.I wouldnt even consider the the tacky look of the gold ,green ,red spray paint. Im sure that it can be accomplished with some degree of success, but Ive never seen anything even close to the yellow cad that comes in a spray can, even if it looks good in a catalog.
As for the platers,yes it can be done to look orginal. I have an NOS booster that I put on my 1968 several years ago and it too is fading even tho its never been out of the garage. It really frosts me to see a “correct” (by owners standards) restoration with a black painted booster. Spring for the extra $25 to get the booster replated and rebuilt. A guy named Steve Gregori redoes them in the correct hue and replaces all rubber for $120. http://www.brakeboosters.com/
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Content last modified: January 22, 2014 at 11:51 pm
Q: Power or Manual Brakes
Dumb nubie question.. How do you know if you have power or manual brakes??? My mastercylinder is shot.. any help??
A: If the master cylindar is bolted directly to the firewall, it’s manual If the master cylindar is bolted to a saucer shaped object (vacuum booster) with a hose connected to the top of the motor, it’s power.
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Content last modified: January 22, 2014 at 11:56 pm
Q: Center Caps
Are the center cap`s on the stock rim`s supposed to have the Pontiac emblem, or the letter`s PMD ? Mine are a black backround with PMD in red capitol`s. Which one should it be ? I think I`ve seen both. Thank`s all.
A: All 1967, 1968, and 1969 and early 1970 Pontiac Rallye II wheels got the black centers with the red letters. The change didn’t occur until well into the 1970 production run, and most cars had the red by about January or February 1970. Late 1970, and all 1971-1972 cars got the red centers with black letters, then in 1973 they went to the polished aluminum with the Pontiac arrowhead emblem.
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Content last modified: February 18, 2014 at 1:58 pm
Q: Brakes 101
I was wondering, when I switch my front drums to disc, can I use the same master cylinder and power brake booster? Do I just need a different proportioning valve or the whole setup? 1969 firebird, hdtp, 350 2 bbl, drums all the way around (for now)
A: You need to understand a couple of basics here. Drum brakes require a check valve in the master to keep the cups in the wheel cylinders upright, which uses about a 5-7 psi pressure maintained in the system. Disc/drum combo systems only have the check valve in the chamber that feeds the rear brakes, as that slight pressure kept applied to discs will wear them out and/or overheat them. You will need to use the disc/drum master cylinder for disc/drum systems, or a 4-wheel disc master cylinder for 4-wheel disc systems. You will also need to use the proportioning and metering valves and light switch appropriate to whatever system you use. Those are separate pieces on the early cars (67 and 1968 GM) with the fixed-position 4-piston calipers, as well as the 69 and 70 GM cars with the newer single-piston system. In 1971 GM changed to the one-piece “combination” valve.
If using a correct 1969 system, it will have a front brake pressure metering valve, mounted under the master cylinder – that’s the rounded piece. This prevents the pressure from going to the disc brakes until the rear brakes have made full contact, since discs are zero clearance while drums have to take up some clearance. Then down the lines a bit will be the distribution block with the warning lamp switch. Some applications (AC-V8 cars, among others) will have another valve mounted on the left side of the subframe, this is the rear brake pressure regulator, also known as the proportioning valve. This slightly reduces the rear braking on nose-heavy cars.
On my 1969 drum brake car I removed the check valves and stayed with the non-power master cylinder when I installed the front discs, and even removed the rear brake check valve after adding the 79 WS-6 disc rear, but I will next add the master cylinder and combination valve from the 1979 car. While it’s drivable, I don’t recommend this tactic for the novice. Of course, this plan could change if I decide to go back to a 69 drum rear end. The disc rear is much heavier and complicates the car far beyond the benefits of 4-wheel disc brakes due to parking brake issues and other things.
I guess if somebody wants a 79 posi rear with brand-new Richmond 3.70:1 gears, reman calipers and the 1967, 1968, and 1969 perches I would probably bail out of it. I don’t think I drove it 1,000 miles before I laid up the car. At this point it might be easier for me to swap the rear back to a Pontiac 3.55:1 than proceed with the rest of the hydraulics and the parking brake cable bracket work.
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Content last modified: January 22, 2014 at 11:56 pm
Q: Rally II Center Cap Installation
I have never seen these Rally II wheels completed inperson. Therefore, how would the caps designed for the older wheels fit on the newer (smaller holes) wheels. I am unfamiliar with their construction and therefore, exactly how the caps attach is a mystery to me.
A: The caps have 3 clips on the back that snap into the round hole as well as 3 other clips that fit into the 3 notches that the larger hole’d wheel has. I guess this is to keep the cap from rotating (I don’t see this as being a problem). I have some of the newer wheels as well and the 3 “possitioning” clips just don’t do anything on these particular rims. If you have a Year One catalog there is a good drawing on page 325 (winter 99 catalog) of how the cap looks from the back as well as these nifty cap locks that keep people from snatching them.
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Content last modified: January 26, 2014 at 12:55 pm
Q: Convert Front Drums to Disc
What do I need to convert my front drums to disc brakes?
A: 1st Gen bolt in brake swap — Mother of all Instructions.
Donor cars:
1969-1972 (possibly 1968 too) A-body, including Chevelle/Malibu/Monte Carlo, Cutlass/442, Skylark,Tempest/LeMans/GTO/Grand Prix. Earlier cars are likely to have the 4 piston caliper, which is more expensive to rebuild. Later cars (’73 and up) have a redesigned spindle that won’t work on a 1st gen. F-body.
1968-74 X-body, Nova, Apollo, Ventura/GTO,Omega. Again, 1975 and later cars were fitted with an incompatible spindle. Don’t go there.
Forget Cadillacs or any of the big B-body cars like the Bonneville, Bel Air, Century, Olds 88/98, etc. Their spindles are too tall, and they are 5 lug on a 5 inch bolt circle most of the time.
Parts from the above qualified cars needed for the swap:
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Spindles
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Calipers
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Caliper brackets
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Rotors
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Master cylinder
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Brake booster (assuming you want power brakes)
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Combination valve (proportioning & other valving function)
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Dust shield
All of the above with the exception of the spindles, caliper bracket, and dust shield, can be used as trade-in cores for new or rebuilt parts from your favorite parts store. Tell the clerk the parts are for a 1969 Firebird, which is the brake system you are recreating here.
Drum brake spindles won’t accept the disk brake calipers without machining. Some aftermarket disk brakes, such as Wilwood, use the drum brake calipers for their setup. If you go that way, keep your drum spindles.
Check the spindles for any scoring or other damage on the bearing load areas. Bunged up threads are unacceptable as well. A number of restoration houses such as Classic Industries and National Parts Depot are selling new spindles just in case you can’t find anything affordable. They can also provide the caliper bracket, the other hard to find component. Dust shields are also being
Don’t pay too much for used parts as most everything will old and worn, and very likely only useful as a core exchange item. Some of the new GM conversion setups on eBay look reasonably priced, and the parts are all new. Just be sure that they are stock replacement parts and nothing kluged together from unnatural sources. For instance, some of the dropped spindle kits use 1978 and later G-body (Malibu/Monte Carlo/Grand Prix/etc) calipers and rotors. These may not perform as well as the earlier A-body stuff, and some of the rotors use metric lug nuts and other hardware.
Also be sure that the kit includes a master cylinder, booster (if needed), and the combination valve. You don’t have a complete brake swap kit without these parts.
Parts from your car to keep:
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Steering arms (1st gen F-bodies are rear steer cars, as are the above x-body cars. A-body cars are front steer. This means that the center link and tie rods sit to the rear of the center axle line. Bolt your F-body steering arms to the A or X-body spindles, and you’re good to go.
New parts to buy:
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Brake Pads
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Front flex hoses (from hard lines to the calipers). Do not, I repeat, do not use old, used, nasty, cracked, and spongy hoses. Always buy new hoses. Is your life or your car not worth the 20 extra bucks?
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DOT 3 or better brake fluid (avoid silicone fluid as it is very difficult to avoid air bubbles and get a good firm pedal). Believe it or not, the Ford DOT 3 is considered about best non-race fluid around. Get it at your local Ford parts department, and take your Firebird when you go. It will improve the neighborhood.
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Inner and outer wheel bearings, races, and seals. Get the Timken brand which are superior to anything else on the market. Most of the standard mainstream parts house brands like GMB are so lousy as to be considered junk. If the store doesn’t have Timken, then find someone who does. They are that good.
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High temp bearing grease. Pick your favorite brand. Natural or synthetic. Avoid the cheap stuff.
Again, say that all of the above parts are for a 1969 Firebird with factory disk brakes when you go parts shopping. This will simplify things, and if you ever need replacement/service parts, they are easily found.
No modifications are needed here to the above parts. You may have to rework the flex hose brackets on your subframe, but not very much as I recall.
You may find that some (as in very few) 14″ wheels will rub on the brake calipers. I don’t know which particular codes will have a problem, so you’ll have to cross that bridge when you get there. You might be able to get away with a thin spacer, but you’ll have to experiment. All 15″ wheels should clear this setup. Disk brakes may push your wheels outward by as much as a quarter inch due to a slightly wider track. If your present tires are very close to rubbing on the outside, the disk brake conversion will make it worse. The stock narrow 205/80-14 or 15 inch tires are not an issue. It’s only an issue when you go to fairly wide tires and wheels that this comes up as an issue. Or if you use after- market wheels with a very deep dish.
Check the condition of your hard lines. If they are rusted, kinked, or the fittings are stripped, you are better off replacing them as well. Fine Lines and Inline Tube are very good at getting you the right parts if you think that your master cylinder or combination valve require unique fittings. Both of the above companies are known to bend up a custom set of lines for any special requirements. But you should find that 1969 Firebird disk brake hard lines should work without any difficulty.
Don’t forget to bench bleed your master cylinder before putting it in the car. This will make bleeding the entire system much quicker.
Upgrades to the above system:
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Consider braided steel flex lines. Many are now DOT approved, and they reward you with an excellent firm pedal.
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Performance pads. A good street compound from Hawk, EBC, or Performance Friction will give stopping performance, little dust, and excellent rotor life.
As usual, be careful when releasing the coil spring in the control arms when swapping spindles. There is a lot of energy in that spring and it’s easy to get hurt. And use proper flair or tubing wrenches on the brake fittings. Regular wrenches are sure to round off the fittings and create problems. Sears is a good source for reasonably priced quality tools. Consult your Pontiac shop manual for the details on removing and installing the brake parts. You do have a shop manual, right? They are readily available from any of the restoration parts houses or even eBay, and are essential to any Firebird owner.
By the way. While catching up on some of the recent postings regarding disk brakes compared to drum, some folks have said that drums aren’t all that bad. To be sure, on the first hard stop, you may get by with drum brakes. But repeated hard stops will soon teach you the meaning of fade. I remember a particularly exciting ride down a mountain pass in my buddy’s ’65 El Camino with drum brakes. After the 3rd big sweeping turn, the brakes rapidly began to fade, and each of the following turns involved a great deal of squealing tires and white knuckles.
It doesn’t take a high speed road course to push one’s brakes to their limit. Just a few hills, or heavy traffic on the way back from the car show. But if you must stick with drum brakes, check out Praise Dyno. They have some very good drum brake components that will really improve performance of the drum system. http://www.praisedynobrake.com/ I’ve been quite impressed with their products.
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Content last modified: January 22, 2014 at 11:58 pm
Q: Speedometer Off
This wonderful hunk of junk from said he had a gto rear end put in, and this is what causes a 10 MPH speedometer offset (due to different gear sizing for the speedo linkup) is there a way to correct this problem easily (if indeed this is the case)?
A: The reason your speedometer is off by 10 MPH is that when the rear end was swapped out, a new one with a different gear ratio was put in it’s place. The gears that drive the speedometer are loacted in the transmission. To correct this problem, you just need to install the speedometer gear for the differential ratio you currently have in your car. Claasic Industries sells these gears and they are easy to replace. Just tell them the type of trans you have and the gear ration in the rear end.
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Content last modified: January 26, 2014 at 1:05 pm
Q: Convert Front Drums to Disc
What do I need to convert my front drums to disc brakes?
A: This is one of the best mods you can do to your car. Factory parts are your best bet (unless your shooting for a custom looking setup). Even junkyard special parts work top-notch once cleaned up. The following list of parts will give you the best performance for cost and reliability:
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Two new GM 1969 spindles (still available from GM) or 1969 – 1974 Nova units for SPC Camaro (or original units if you can find them)
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Two junkyard caliper brackets from a 1968 – 1978 midsize GM car using a corporate front wheel disc setup
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Two Nova or Cutlass (corporate) calipers for cores from the local parts store – eat the core charge (if low) to save canvasing the junkyard
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One new/rebuilt master cylinder (don’t use junkyard units for this) for 1969 SPC Camaro (or for 1969 – 1972 Nova with front disks for places that charge extra when they hear the word Camaro or Firebird)
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One set of first gen (or Nova) lines, hardware, and adjustible P-valve
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One powerboster either new or from almost any late ’60s to mid ’70s GM
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Two rotors – 1969 SPC Camaro or 1969 – 1972 Nova
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One alignment after swaping
If you keep your eyes peeled, and piece it together, you can probably do the swap for about $100.
A: Tips for the single-piston disc brake setup conversion: the first-gen stocker ’14 rims will NOT work with disks. If you have these, plan to use 15″ rallys or a custom rim. (ADMN NOTE: Actually, it has been determine that Rally II Rim Code “JC” was used on both disc and drum equipped 1968 Firebirds)
use stock parts for a driver! they are over engineered and ultra reliable, not to mention replacable on the road. Keep a record of the year parts you use since there are slight differences between the years.
Of all these parts, only the caliper brackets, proportional valve, and metering valve are parts no longer in production, so make sure you get good ones. remember, the valve stuff can be replaced with an adjustible one, I dont like them, but they are worth a few feet.
use calipers for cores if they’re crap. quality rebuilds of single pistons are cheap!
if rotors are like new (thick and no valley wear) use’em they work fine, else buy new. never mix new and old.
backing plates are a easy to find, even new ones are cheap. if in the junkyard, subsitute a bent one for the best you can bolt up.
rubber lines. DONT REUSE, its not worth it, but take them to match the caliper and bracket ends for the new ones. reuse the caliper bolt washers, old ones seal better then new ones.
line mounting flanges keys are different, plus the mount point is relocated from the drum position, so take’em if they are not the welded type (Chevelle/A-Body)
1969 Camaro/Firebird or ’68-74 Nova/X-Body lines are direct drop-ins, use’em if good. if theyre crap, then use then as guidelines for new ones. swipe the fittings and armco(?) if you make your own.
The ’70(-’71?) camaro rear brake mastercylinder-to-proportional valve line tucks out of the way and looks bitchin compared to the 1969 Camaro/Firebird or ’68-74 Nova/X-Body version.
buy a new high volume master, I recommend the 1967 vette, 1967-1968 Z28, 1967-1968 J52/J56 (all the same) GM “fat-boy” master. The 1969 standard disk master will do, but the fat-boy looks way cooler, and has a bigger bore (if I remember correctly)
when you replace the master (?) make sure the hole depth for the push rod is the same on the new master as the old (since its a rod with manual brakes not a replacable pin)
I recommend a new booster for a 1969, dont waste your time (experience here) to save some bux. masters come needing long or short pins, swipe the correct pin from the junkyard to fit your master/booster combo. do this before install day. 🙂
I also forgot the most important tip: never use a drum-drum prop valve on a disk-drum car, the different front-read balance will result in severe lock up of the rear wheels.
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Content last modified: January 22, 2014 at 11:59 pm
Q: Speedometer Off Error Calculation
Basically, if I got from the stock 225/70-15 to a 245/50-16 wheel/tire combo, will my speedo read faster or slower than I am actually going? Someone said there is like a 7% difference in the wheel/tire combo.
A: The 225 is the treadwidth in mm, the 70 is the aspect ratio (% sidwall of treadwidth), and the 15 is the rim diameter. With this, the overall assembly diameter and circumference is:
225/70-15 27.4″ diameter and therefor 172.16″ circ.
245/50-16 25.6″ diameter and therefor 161.14″ circ.
At 70 MPH with the stock assembly, the rear axle will spin approx 429.45 rpm.
At this same rpm (and same speed on the speedometer), the second setup will actually be going only 65.5 mph while the speedo will indicate 70mph, an error of about 6.8%.
A quicker way to determin the error is to simply ratio the assembly diameters:
1 – (25.6/27.4) = 0.0656 or about 6.6%.
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Content last modified: January 26, 2014 at 1:06 pm
Q: Convertable Front Drums to Disc (Revisited)
What do I need to convert my front drums to disc brakes?
A: The 1st Gen Firebirds can use the “early” GM single piston caliper setup. (That is the “corporate” setup – 68-72or74? midsize cars and Nova clones) It came on 1969 Firebirds/Camaros as an option. Don’t spend the $825 for a kit, unless you don’t have any salvage yards around. You should be able to get the wheel assemblies and proportioning valve for $150 – $250. You have to use the Firebird steering arm from the drum brake spindle – transfer it to the disk brake assembly, keeping right and left straight.
You should use the disk brake proportioning valve. It realy is a “combination valve” – the 1968 V8 A/C disk brake Firebirds used a separate proportioning valve, which is different. Another alternative is use the drum brake warning light switch/divider block, and put an aftermarket adjustable proportioning valve in the line to the rear brakes only.
You absolutely have to use a disk brake master cylinder!!!!! It has to be one for power brakes if you have them.
The booster is the same, with the exception of the push rod lengths – you have to see if it pushes on the master cylinder or not – there is an inch or so difference in the masters, I think. The rod to the pedal has to match the car, too. But if you already have power brakes you are all set there.
For my 1968 Firebird, I got new rotors, bearings, hoses, rebuilt calipers, booster, master, plus the junkyard spindles, brackets, splash shields for around $500 total. I painted them with Eastwoods spray paints and they look like $1 million. The car’s not done yet, so no driving report.
Q: Is it absolutely imperative to get the booster and proportioning valve? I got a set of disk brakes from a guy to put on my 1969 several years back and only got the disk brake units.
A: The booster may not be a critical item because you can buy one as a replacement unit from your local parts store. But, the push rod that connects to the brake pedal may be different between drum and disc systems.
The proportioning valve is critical. The disc and drum units are completely different. On some disc systems (like my 69′) there is a separate slave proportioning valve for the front discs. I don’t think you can purchase a replacement from the dealer but you can probably get one from someone like Ames. I’ve also seen them advertised as a separate item from some of these disc brake conversion companies.
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Content last modified: January 23, 2014 at 12:01 am
Q: Speedometer Off – Revisited
I have a 1968 Bird and the speedometer is off 6 miles an hour fast. I have 14′ rims and 215/70/14 tires. I’m missing something here. Could someone tell me why its off? I have the 160 speed-o. Is that whats off, or is it something else?
A: I suspect the speedometer gear drive in the transmission is not correct for the current combo (tire size). Just because your running 14″ tires doesn’t mean that they are the original profile. You can try to fix it yourself by changing the drive gear or there should be a shop in your area that can do it for you and certify the speedo. Another option would be to go with reproduced originals instead of correcting the speedo.
A: Same problem here but fixed with a different colored drive gear in the trans, I cant remember which color slowed my speedo but they are bout eight bucks apeice and can be found at most gm dealers. It is the little plastic gear that is on the end of the speedo cable that conects to the trans.
A: Unless your trying to keep the car 100% original, it makes more since to get the tires you want and then correct the speedo. If you want to go to a comparable tire size as original, then check out: http://www.wrljet.com/tires.html
A: I agree with whoever said to pick the tires you like, then calibrate the speedo. But if you want original size tires here’s some advice.
Originals would have been E7014 or F7014, probably F7014. Here are some sizes that are similar:
Size | Diameter |
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E7014 | 25.8 |
F7014 | 26.2 |
195/75R14 | 25.5 5.1 Tread |
205/75R14 | 26.1 5.3 Tread |
215/70R14 | 25.9 6.0 Tread |
225/70R14 | 26.4 6.3 Tread |
A: If you have 215/70/14 tires, they should be pretty close to your originals and shouldn’t make you off by more than 1% or so. I would guess then that your speedo is off by 3.23/3.08 or 5% making it read about 74 when you’re driving 70. I’m going to include here an answer I posted on the classical pontiac site for a guy that swapped to 3.73 gears in case it helps.
I just did this for a 2.56 to 3.23 swap in a TH350. There are three ways to do this.
For the first one, find out exactly how far off it is… try using the odometer to check how many miles you read when traveling 10 miles according to mile markers. You should get a ratio like 2.25:1 (based on your 90 MPH at 40 MPH guess). Next, pull the speedo gear and housing out of the trans. Count the number of teeth on the gear (driven gear). Also, count the number of teeth on the gear it mates to on the output shaft of the trans (drive gear). Take the number of teeth on the driven gear and divide by the number on the drive gear. Lets say you get 35/19=1.84, now multiply by how far off your speedo is (like 2.25) and you get 4.14 (in this example). This is what the final driven gear to drive gear ratio needs to be. You may also need to change the driven gear housing since they only house ranges of gears like 36-39, 40-43, etc.
The second way to do this is to use one of these formulas:
Drive Gear = (.0495835 * Tire Dia * Driven Gear) / Gear Ratio.
OR
Driven Gear = (20.168 * Gear Ratio * Drive Gear) / Tire Dia.
And here’s a third way, call GM part supplier. They’ll want to know Gear Ratio, Tire Size, type of Trans and then he can give you GM part numbers for the gears and housing.
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Content last modified: January 26, 2014 at 2:47 pm
Q: Disc Brake Conversions (More)
Does anyone know of any other donor cars for disc brake assembly other than the Nova and clones. Is there any way to put 2nd gen. F-Body discs on ours?
A: I just wrote a letter about that a few days ago! The spindles with all the disc stuff attached can be used from any 1969 to 72 A-body, that’s Chevelle, LeMans, Cutlass, Skylark, and all the derivatives (442, GTO, F-85, GS). You need to use the steering arm from your drum brake Firebird, and I can’t answer about differences regarding the metering valve. I CAN tell you that the 1969 and 70 A-body used the separate valves like the 1969 F-car, but the 71 and 72 used a combination valve. Also there was a slight difference in the boosters, I believe the A-cars had a letter “A” stamped on the pushrod through the firewall.
I think the 2nd gen F-car components present some difficulties, maybe somebody out there has tried this.
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Content last modified: January 23, 2014 at 12:02 am
Q: Largest Size Wheels Can I Put on My 1968
What is the largest size wheels I can put on the rear and front without any modifications to a pretty much stock-like drivetrain set-up? I have traction bars on the rear, but that’s about it. Right now I have 14×6″ Rally II’s on the front, and 14×7 Rally II’s on the rear. I wanted to get some 15×7 or even 8″ wheels to put on the rear and was wondering if this would fit without any modifications being necessary. Jeg’s is selling Rally II replica wheels for only $92ea for the 15×8’s!
A: 15×8 will not fit inside the stock wheelwells. The front and rear will handle up to 235-60×15 without a problem. The rear could go up to 255 if you roll the lip of the quarter/wheelhouse. Remember, rim offset is critical. If you plan on using after market wheels a good rule of thumb is to lay a straight edge vertically on the front of the drum then measure the distance from the edge to the fron and back of the wheelhouse. Give yourself 1″ (max clearance) to 1/2″ (min clearance) on each side to allow for tire sidewall buldge.
A: I put 15 x 7 with 235 60 15 on my 1967 and it looks great. It had 14 x 6 on it but now the fender wells are full and looks great.
A: I have seen a 1968 with 15×8 wheels and 275/50/15 tires on the rear. They loked great and did not rub. The wheels did seem a bit narow for those tires (I would go with 9.5 to 10 inch wide, as 275 tires are almost 11 inches wide) but the owner was only concerned with straight line performance only. I don’t have information on backspacing, but I see Camaros of the same year running around like that all the time. I would assume it is common knowlege at the wheel store. 235/60/15 is as wide as I would go in the front but they would have an outside diameter that is slightly larger that your rears (235/60/15= 26.1in. outside diameter, 275/50/15= 25.83in.). I suggest 225/60/15 in the front for this reason (25.63in. outside diameter). Tires of smaller or significantly larger diameter in the rear can have adverse effects on handeling. It’s fine at the strip, but a chore on the street.
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Content last modified: January 26, 2014 at 1:26 pm
Q: Front Disc Brakes Conversion (Even More)
I own a 1968 Firebird Coupe, with what I call the death drum brakes on the front. I plan on putting disc on the front. Has anyone done this before? What are the necessary parts I need to get? I would like to get the parts from a pick and pull wrecker yard. Any help would be great. I just started restoring my “first car” It’s been in storage longer than I’ve driven it (21 years owned it, 6 years driven). So any help would be great.
A: I’ll share my experience with all of you, since there might be some useful bits here.
My car originally came with drum brakes, and had been sitting in a San Francisco carport for about 5 years. The brakes were in pretty bad shape. When I tore the car down for restification, I decided that I wanted to upgrade to front discs. At about the same time, I found an ad locally for the following 1969 Firebird parts:
Used Calipers & Flex hoses
Spindles & Caliper brackets
Upper & Lower Control Arms
Front Rotors
I used the calipers as cores and bought rebuilt units, without pads. The 2 piece rotors were revealed to be too thin to resuse. But I had a set of new 1 piece rotors for an El Camino that turned out to be a direct replacement. I then bought new braided stainless steel hoses, Performance Friction carbon metallic pads (only $24!), a complete set of stainless repro hard lines, new bearings, and new rear brake hardware as well as shoes.
The control arms had new lower ball joints, but one had damaged threads on the spindle stud, so I replaced that. They both had new rubber bushings, but the upper arms needed new bushings as well as ball joints. I had all of the used parts beadblasted, and then had a machine shop install the one lower ball joint as well as the upper arm bushings. Once that was done, I painted everything with POR-15. I also cut 1 coil off the front springs, blasted and painted them. The car sat a bit high up front by my tastes. Once assembled, the height was just what I wanted.
Other parts I got were a rebuilt master cylinder, along with a rebuilt booster. The rebuilder offered to plate the booster in silver cad, versus gold cad which most restoration parts suppiers use. Silver cad is actually the correct plating used by Pontiac, and while I wasn’t doing a restoration, I liked that detail. The old drum brake master/booster was acceptable as a core. I had a new prop valve from Master Power Brakes that I’d bought for another car, but didn’t use.
Upon assembly, most things went on pretty easily. The problem areas might be of interest to some.
Rear Axle hardlines needed minor rebending to fit the 2nd gen. housing I was using. The 8.5″ has a different location for the flex line mouning as well. Not a big issue.
The front to rear line had a different sized fitting compared to the port on the rear of the prop. valve. I was able to find a correctly flaired adapter to make the two fit. The bends in the line were in all the right places and fit very well otherwise.
The 1969 flex line brackets were not a direct bolt on to my 1968 subframe, and figuring out the best mounting location was difficult. I didn’t have a 1969 disc brake car to use as a reference, so I guestimated the ideal location. Getting the hardlines to cooperate with these locations was a bit difficult. Stainless lines are quite a bit harder than the mild steel originals, and are a but tougher to bend. Even harder to flair if you use bulk line to create your own.
Driver side fitting didn’t match the appropriate port on the prop valve. There wasn’t an adapter to be found that had the right sided flair, and so I had to get a line made up at a local shop that made up hoses and lines for industrial equip- ment.
Each of these problems were time consuming to resolve, and were a source of occasional frustration. I can see where buying a complete conversion kit from someone like Master Power Brakes, Classic Industries, or one of the many other sources would probably result in less fabrication, and take less time to install. I was on a very tight time sched- ule, and could ill-afford the time lost. I was trying to get the car ready for Hot August Nights ’99 in Reno, Nev.
I got all of the problems resolved, but wondered if I would have been better off buying a kit. Costwise, I came in just about $195. more than the kit. But I got some better parts as a result.
Cost Comparison:
Part | Cost |
---|---|
Used Parts: | |
Rotors | (turned out to be unusable) |
Rotors | (turned out to be unusable) |
Calipers | (used as cores) |
Brackets | |
Control Arms | (upper and lower) |
Hoses and brackets | (dumped the hoses, used the brackets) |
Total | $180.00 |
New/Rebuilt Parts: | |
Calipers x2 (Bendix rebuilds) | $30.00 |
Beadblasting various parts | $50.00 |
Rebuilt Master and Booster(incl. plating) | $125.00 |
Stainless Brake lines,front,rear,axle | $239.00 |
Braided stainless flex lines(front and rear) | $70.00 |
Front Brake Pads (Performance Friction) | $24.00 |
Front Wheel Bearings and Seals | $30.00 |
Fabricate New LH Hardline | $15.00 |
Misc. flaired nut adapters | $12.00 |
1 Piece Front Rotors (Bendix) | $90.00 |
Proportioning Valve (Master Power) | $125.00 |
Total | $810.00 |
Combined Total | $990.00 |
Not included are brake fluid, rear shoes, rear brake hardware, rear axle seals, upper control arm bushings, and new front end parts like ball joints, idler arm, inner and outer tierods, rear springs and related hardware. All of which were replaced, but not related to the disc brake conversion.
Firebird Specialties sells a front disc brake kit, with all new components, for $795. I don’t know if the hardlines are mild steel or stainless. I assume they are mild. Some of these kits have a cad. plated booster, others have a painted booster. All feature regular rubber flexlines. They also sell a kit w/used parts for $350. But research would be needed to determine what would need to be replaced or repaired in that kit.
Overall, I’m very happy with the performance of the brakes. Stopping is excellent, with no drama what- soever. The PF pads don’t squeak, and don’t seem inadaquate when cold. It was a bear resolving some of the compatibility issues, but the results make it worthwhile.
A: In corrisponding with another list member, it has come to my attention that I should have been a bit more clear on in the disk brake story that I related. The minor question he had led me to think about some of the other things I wrote about.
-It wasn’t necessary to change the control arms when upgrading to disk brakes. I got the spare set of arms as bonus material with the brake conversion parts. Having extra arms allowed me to prepare them and still have the car able to roll around. Also, while I was getting these parts ready, the car was in the body shop, so being mobile was especially useful. And since I was on a short schedule, any place where I could multi-task was helpful. But the control arms are OK for either brake system.
-Actual cost. Ever read a magazine article where some guy boasts that he’s got only $3500 in a car, but has replaced the engine, trans, interior, and repainted the car? Seem bogus to you too? I listed all of the costs, even for those parts I aleady had. That way you know the whole story. Kind of like the new slant that the magazine Car Craft has taken lately. They list all of the hassles they run into, and even list little items like the cost of bearing grease and zip ties. I didn’t get that detailed, and there were plenty of trips to hardware stores for stainless steel fasteners, clips, and whatnot that didn’t get into the cost. But you did get a fairly good representation of what it took to get the car converted.
Brake lines. I got rid of all of the old lines, yet descibed the car as having sat for only 5 years. When I opened the master cylinder up, and also when I opened one of the brake lines, what poured out was dark like coffee, and had lots of rust flakes floating in it. A clear indication that the brake system was rusting on the inside. Many of the flaired nuts at various joints were either rusted or had the corners rounded off. My feeling was that the car probably sat for even longer with previous owners, and I didn’t want to build my brakes on a shakey (or rusty) foundation.
Extra upgrades. I admit to being a bit excessive when it comes to nearly anything automotive, but especially brakes. I could have save some money on brake hoses rather than use the braided steel units. And I probably really didn’t need the carbon metallic brake pads, or stainless steel lines. But, since I was replacing all that stuff, I wanted it done the best way possible, within the limits of my budget.
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Content last modified: January 26, 2014 at 4:05 pm
Q: Maximum Wheel and Tire Sizes
What is the largest size tires I can put on my Firebird?
A: The March 2000 issue of Car Craft has an article that deals with maximum wheel and tire sizes for various cars. It has a section on the 1967, 1968, and 1969 Camaro and Firebird and below is the text of that portion of the article.
1967, 1968, and 1969 Camaros and Firebirds
15-inch: 15X8 with 4.5-inch backspacing front and rear. With some tires the rear shocks will have to be mounted inboard; if you do that, some combinations of 9-inch wheels will work with 5.5-inch backspacing.
16-inch: 16X8 with 4.5-inch backspacing front and rear. The rear shocks will have to be relocated inboard. Use tires with an aspect ratio of 50 or less with section widths of 245 to 250.
17-inch: 17X9 with 5.5-inch backspacing front and rear. There may be lower control arm contact with some steering gears. Use tires with an aspect ratio of 40 or less and section widths of 245 to 255.
18-inch: 18X9 with 5.5-inch backspacing front and rear. Use tires with an aspect ratio of 35 or less with section widths of 245 to 25 in front and 275 in the rear.
A: Been several posts in the past on this Biggest size on an unaltered 1967, 1968, 1969 is 235-60 x15 on 8 in wheels G has 225s on 8 in snowflakes, I used 235s on 7 in snowflakes tried 245 on 8 in snowflakes and was too big.
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Content last modified: January 26, 2014 at 1:39 pm
Q: Front Disc Brake Conversion
hi guys i just got the front brake set up on a nova[think 74] but anyway the steering linkage is behind the tires but the question i have is do i need the upper and lower control arms to or not i was planning on going this friday to pull them off i was going to get the spindals and all attaching hardware rotors,calipers,etc as well as the prop. valve is there anything else i need allready have a new booster and disc-drum master clind. any help would be great as i know a lot of you guys have allready done this.
A: All you need is the spindle and it’s attached hardware (dust shield, caliper bolts, etc.). Just remove the upper and lower ball joints and take everything inbetween. You may also want to take your new booster and compare it to the one on the car (just to be safe). Sometimes the push rod from the pedel to the booster is a little different.
If possible, you may consider pulling the front steel brake lines. You know they fit and you can always use them as a model for new ones.
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Content last modified: January 23, 2014 at 12:08 am
Q: 255’s or 235’s on 15×7 Ralley IIs
Does anyone know if 255 70 R15’s or 255 90 R15’s will rub on 15x 7 Ralley II’s if I put them under my 1968 Firebird 400 car? I know I’ve heard much about this in the past.But just cant recall.
A: I’ll assume that the above “255 90 R15” is really 255 60 R15. A 90 series tire would be very tall and skinny indeed.
What will fit will depend partially on how much, if any, your car sags in the rear, or has been lowered in any way. So a simple answer is difficult to offer that would be accurate in any way.
Here is how the tires stack up in diameter:
Size | Diameter |
---|---|
205/70R14 |
25.3 (an approximation to a stock size) |
235/70R15 | 28.0 |
235/60R15 | 26.1 |
255/70R15 | 29.1 |
255/60R15 | 27.0 |
As you can see, the 70 series tires are noticably taller than the 60 series tires, and some of these sizes are more than 3.5″ taller than the stock tire. You need to check your present clearance to see if you can fit tires these sizes as your car sits now. Air shocks will of course get you more clearance, but they have their own problems and I would not reccommend their use.
Up front, many owners run 225/60 or 70-15s, and I run 235/60-15 without problems. others report rubbing with some of these sizes. I get a little rubbing on steep or off-camber driveways. I think that a 255/70 or 60 in front is too tall and would definately rub unless your car sat very high. At least one member reports running 245/50-15 up front, and he can tell you about what problems if any he’s encountered. I find that this is too wide for my car with my present offset wheels. That’s a 7 inch Ralley II.
In back, members have reported running 255/60s without much trouble. I think that a 7 inch wheel my be too narrow for this tire and will not allow the tread to fully meet the road surface. Excessive wear in the middle will result, and you will not get the full effect of this width tire. An 8 inch wheel will be much better. An offset of 4.5 inches should allow you get that tire inside the wheel well, though at 27 inches tall, you need to check for adaquate clearance.
A: Been several posts in the past on this Biggest size on an unaltered 67-9 is 235-60 x15 on 8 in wheels G has 225s on 8 in snowflakes,I used 235s on 7 in snowflakes tried 245 on 8 in snowflakes and was too big.
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Content last modified: January 26, 2014 at 5:35 pm
Q: Upgrading to Disc Brakes on 1968
One of the first things that I would like to do to the 1968 is improve the braking system for SAFETY of my family. Do you recommend disc all the way around? This car has no power brakes right now and drums all around.
What components from which cars will I need to start collecting now so that I have the parts when I go to do it? Can you compile a shopping list for me?
A: Do you want the correct-for-68 4 piston disc brakes, or the 1969 style single piston set-up? The 4-wheel discs are nice, but not necessary, and maybe more work than necessary to achieve what you are looking for. Your best bet (barring the correct 4-piston system) is the 1969 F-body style and you can get with the guys who offer a complete set-up with some new parts, for a very easy change-over. If you can do your own brakes, get the master cylinder, booster, and related valves attached to it all from a 1969 bird or camaro.
If possible, get the spindles with the disc brakes atatched from the same car, or from a 69-72 A-body, it has the parts you’ll need. A-body cars are Chevelle, Skylark, Grand Sport, LeMans, Tempest, GTO, Cutlass, F-85, 442. The 69-72 spindles are the same, but the steering arm is different. However, the steering arm unbolts, and the Firebird one bolts on in its place. The spindles are a little different from drum to disc, but the same from F to A body.
On the list in the past week, it has been mentioned that some 1969 birds had a valve along side the left frame rail under the drivers seat, in the line to the rear brakes. This was for proportioning the system in cars that had V8 and AC, reducing the rear braking slightly.
Just so you know, the 1969 and 70 GM disc cars had separate valves for metering, proportioning and differential (the warning light switch). In 71 and later, GM went to a combination valve, incorporating all these things in one unit, usually found a couple feet below the master/booster assembly, mounted on the frame rail corner.
Still a few donors left out there. 69-72Grand Prix, Pre74 Nova, Apollo, Omega, Ventura ,70-72Monte Carlo, 68-72 A Body GM(Skylark, Chevelle, Cutlass, Lemans. Just try to get entire system; spindles, brake line, bracket, master cylinder & booster with proportioning valve.
I’ll share my experience with all of you, since there might be some useful bits here.
My car originally came with drum brakes, and had been sitting in a San Francisco carport for about 5 years. The brakes were in pretty bad shape. When I tore the car down for restification, I decided that I wanted to upgrade to front discs. At about the same time, I found an ad locally for the following 1969 Firebird parts:
Used Calipers & Flex hoses
Spindles & Caliper brackets
Upper & Lower Control Arms
Front Rotors
I used the calipers as cores and bought rebuilt units, without pads. The 2 piece rotors were revealed to be too thin to reuse. But I had a set of new 1 piece rotors for an El Camino that turned out to be a direct replacement. I then bought new braided stainless steel hoses, Performance Friction carbon metallic pads (only $24!), a complete set of stainless repro hard lines, new bearings, and new rear brake hardware as well as shoes.
The control arms had new lower ball joints, but one had damaged threads on the spindle stud, so I replaced that. They both had new rubber bushings, but the upper arms needed new bushings as well as ball joints. I had all of the used parts beadblasted, and then had a machine shop install the one lower ball joint as well as the upper arm bushings. Once that was done, I painted everything with POR-15. I also cut 1 coil off the front springs, blasted and painted them. The car sat a bit high up front by my tastes. Once assembled, the height was just what I wanted.
Other parts I got were a rebuilt master cylinder, along with a rebuilt booster. The rebuilder offered to plate the booster in silver cad, versus gold cad which most restoration parts suppiers use. Silver cad is actually the correct plating used by Pontiac, and while I wasn’t doing a restoration, I liked that detail. The old drum brake master/booster was acceptable as a core. I had a new proportioning valve from Master Power Brakes that I’d bought for another car, but didn’t use.
Upon assembly, most things went on pretty easily. The problem areas might be of interest to some.
-Rear Axle hardlines needed minor rebending to fit the 2nd gen. housing I was using. The 8.5″ has a different location for the flex line mouning as well. Not a big issue.
-The front to rear line had a different sized fitting compared to the port on the rear of the prop. valve. I was able to find a correctly flaired adapter to make the two fit. The bends in the line were in all the right places and fit very well otherwise.
-The 1969 flex line brackets were not a direct bolt on to my 1968 subframe, and figuring out the best mounting location was difficult. I didn’t have a 1969 disc brake car to use as a reference, so I guestimated the ideal location. Getting the hardlines to cooperate with these locations was a bit difficult. Stainless lines are quite a bit harder than the mild steel originals, and are a but tougher to bend. Even harder to flair if you use bulk line to create your own.
-Driver side fitting didn’t match the appropriate port on the prop valve. There wasn’t an adapter to be found that had the right sided flair, and so I had to get a line made up at a local shop that made up hoses and lines for industrial equip- ment.
Each of these problems were time consuming to resolve, and were a source of occasional frustration. I can see where buying a complete conversion kit from someone like Master Power Brakes, Classic Industries, or one of the many other sources would probably result in less fabrication, and take less time to install. I was on a very tight time sched- ule, and could ill-afford the time lost. I was trying to get the car ready for Hot August Nights ’99 in Reno, Nev.
I got all of the problems resolved, but wondered if I would have been better off buying a kit. Costwise, I came in just about $195. more than the kit. But I got some better parts as a result.
Cost Comparison:
Part | Price |
---|---|
Used Parts: | |
Rotors | (turned out to be unusable) |
Rotors | (turned out to be unusable) |
Calipers | (used as cores) |
Brackets | |
Control Arms | (upper and lower) |
Hoses and brackets | (dumped the hoses, used the brackets) |
Total | $180.00 |
New/Rebuilt Parts: | |
Calipers x2 (Bendix rebuilds) | $30.00 |
Beadblasting various parts | $50.00 |
Rebuilt Master and Booster(incl. plating) | $125.00 |
Stainless Brake lines,front,rear,axle | $239.00 |
Braided stainless flex lines(front and rear) | $70.00 |
Front Brake Pads (Performance Friction) | $24.00 |
Front Wheel Bearings and Seals | $30.00 |
Fabricate New LH Hardline | $15.00 |
Misc. flaired nut adapters | $12.00 |
1 Piece Front Rotors (Bendix) | $90.00 |
Proportioning Valve (Master Power) | $125.00 |
Total | $810.00 |
Combined Total | $990.00 |
Not included are brake fluid, rear shoes, rear brake hardware, rear axle seals, upper control arm bushings, and new front end parts like ball joints, idler arm, inner and outer tierods, rear springs and related hardware. All of which were replaced, but not related to the disc brake conversion.
Firebird Specialties sells a front disc brake kit, with all new components, for $795. I don’t know if the hardlines are mild steel or stainless. I assume they are mild. Some of these kits have a cad. plated booster, others have a painted booster. All feature regular rubber flexlines. They also sell a kit w/used parts for $350. But research would be needed to determine what would need to be replaced or repaired in that kit.
Overall, I’m very happy with the performance of the brakes. Stopping is excellent, with no drama what- soever. The PF pads don’t squeak, and don’t seem inadaquate when cold. It was a bear resolving some of the compatibility issues, but the results make it worthwhile.
A: In corrisponding with another list member, it has come to my attention that I should have been a bit more clear on in the disk brake story that I related. The minor question he had led me to think about some of the other things I wrote about.
-It wasn’t necessary to change the control arms when upgrading to disk brakes. I got the spare set of arms as bonus material with the brake conversion parts. Having extra arms allowed me to prepare them and still have the car able to roll around. Also, while I was getting these parts ready, the car was in the body shop, so being mobile was especially useful. And since I was on a short schedule, any place where I could multi-task was helpful. But the control arms are OK for either brake system.
-Actual cost. Ever read a magazine article where some guy boasts that he’s got only $3500 in a car, but has replaced the engine, trans, interior, and repainted the car? Seem bogus to you too? I listed all of the costs, even for those parts I aleady had. That way you know the whole story. Kind of like the new slant that the magazine Car Craft has taken lately. They list all of the hassles they run into, and even list little items like the cost of bearing grease and zip ties. I didn’t get that detailed, and there were plenty of trips to hardware stores for stainless steel fasteners, clips, and whatnot that didn’t get into the cost. But you did get a fairly good representation of what it took to get the car converted.
-Brake lines. I got rid of all of the old lines, yet described the car as having sat for only 5 years. When I opened the master cylinder up, and also when I opened one of the brake lines, what poured out was dark like coffee, and had lots of rust flakes floating in it. A clear indication that the brake system was rusting on the inside. Many of the flaired nuts at various joints were either rusted or had the corners rounded off. My feeling was that the car probably sat for even longer with previous owners, and I didn’t want to build my brakes on a shakey (or rusty) foundation.
-Extra upgrades. I admit to being a bit excessive when it comes to nearly anything automotive, but especially brakes. I could have save some money on brake hoses rather than use the braided steel units. And I probably really didn’t need the carbon metallic brake pads, or stainless steel lines. But, since I was replacing all that stuff, I wanted it done the best way possible, within the limits of my budget.
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Content last modified: January 26, 2014 at 3:51 pm
Q: Tires for 14×7 Rally II Rims
I have set of 14*7″ rallye II rims that i’m going to put some rubber on. Does anyone know what size tire i can get on these and fit them comfortably inside a 1967 wheel well?
A: I dont know what offset your wheels have so use the following: all around size is 225-60×14 to be safe I have used 235 in front (rear is no problem) but its close. Rear can go with a 255 or 265 but depends on offset. I personally have grown out of the mismatched front to rear for a street driven car. All of these sizes can be put on a 7in wide rim
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Content last modified: January 26, 2014 at 5:37 pm
Q: Upgrading to Disc Brakes (Forgotten Tasks)
I just picked up the whole front disc components off of a 1969 ‘bird to put on my 1968 with drums in front. It came off of a working (stopping) car. I have a non-power drum all the way around on my 1968.
Besides new pads, is there anything that i should do to the booster or master cylinder to ‘freshen it up’? Is there anything inside the booster that needs a new seal or anything like that? There is a white plastic bushing ‘thingy’ that sleeves over the rod that goes into the back of the booster that is in pretty sorry shape. Is this something that I can replace easily and inexpensively? I plan on getting the rotors turned for about $7 each at Kragen. Anything else I should do to have essentially ‘good as new’ brake components???
The whole unit is pretty cruddy (grimy/rusty) and could use being cleaned up and painted. Any good ideas of what and how to clean it up with? How about paint? Regular enamel do okay?
By the way, I noticed that the rotors on one side came from a wrecking yard (telltale markings of painted numbers)and has a groove in the middle of the rotor that obviously came manufactured that way. What is up with that??? Used for cooling on another vehicle maybe?
As far as the proportioning valve is concerned, will this need to be adjusted if it already came off of a 1969 with discs in front, drums in rear?
A: I’d consider performing a vacuum test on the booster. If it leaks, you can then use it as a exchange core. You can wire brush the rust and crud and paint the booster. Eastwood sells a paint kit that reproduces the cad. look. But it is my understanding that silver cadmium was in fact the correct color. Most lower priced rebuilt units are painted (black) and not plated. You can get a rebuilt unit plated for extra money. I did this.
If it were my car, I’d probably use the master cylinder and calipers as core exchanges as well. This way you have reliable rebuilt or new parts for these critical items. If the caliper pins/bolts are pitted or badly rusted, get rid of them. You should be able to find replace- ments at a good auto parts store. Look at the HELP! brand display. Dump the flex lines since they are old and will most likely fail when you most need them. New brake hoses are not terribly costly.
As for things like brackets and spindles, get them hot tanked at your local machine shop. See if they will bead blast them for a reasonable fee. I did this and found the cost reasonable. This leaves a surface perfect for painting. You can then paint using your favorite system. I used POR-15.
I’ve seen original style 1969 rotor with that groove, and replacements without it. The original rotors are 2 piece. They rotor itself bolted to the hub. They are hard to find, and are costly. Most replacements are 1 piece, less expensive, and your car won’t know the difference. 1969-72 Nova/Chevelle/LeMans/Omega/Ventura/Skylark will interchange, among others. I have no idea what the groove was for.
The stock proportioning valves are non-adjustable. You must get the disk brake unit from the donor car, or buy a new one from someone like Master Power Brakes.
A lot of auto parts stores will set their brake lathe to mill the rotor to the minimum thickness. The end result will be that you will not be able to turn those rotors again in the future.
Have them checked for warpage and thickness. If not warped, just clean them up and use them. The brake pads will get rid of the surface rust (assuming no pitting). But they need to be clean.
I’ve seen two types of proportioning valves. One has 1 line to the rear. This goes to the rear wheels. It then has 1 line out on each side, which is for each front wheel. It also has 2 inlet ports, one for each chamber in the master cylinder.
The other type has one less outlet port. That is to say that it relies on a second smaller valve that splits the single front line in two, one for each wheel. I suspect you have this one.
Inspect your balljoints and other front end parts for wear, and replace accordingly. Take a look at the rear brakes too.
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Content last modified: January 23, 2014 at 12:10 am
Q: Original Tires
Can someone tell me what tires were original on a 1968 400 Firebird?
A: Several types of tires (Firestone) were used on the 1968 Firebird.
Standard on the Base Firebird was the E70x14 B/W Wide Oval.
Standard on the Sprint, 350, 350 & 350 HO was the F70x14 B/W.
Only the 400 Model received the F70x14 Redline Wide Oval.
Optional were:
E70x14 Redlines
E70x14 Whitewall
I95Rx14 Whitewall Radial (rayon)
F70x14 Redline, Whitewall & Blackwall
The type of tire was noted on the Fisher Body Broadcast Copy and on the PMD Billing History Card
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Content last modified: January 26, 2014 at 5:39 pm
Q: Reproduction Goodyear Polyglass Tires
I’m about to spend a whole lot of money for new tires to put on my 1967. I’m planning on coughing up the big $$$ for the period correct Goodyear Polyglass tires that classic industries resells. The problem I have is; which size to go with, the F70-14 or the E70-14? The car originally came with E70-14s, but I seem to recall that back in high school, (a very long tiome ago), I had a set of F70-14s mounted on 14 x 7 Rally IIs, and I don’t remember having any clearance problems then.
Currently, my car has Goodyear Eagle VRs, mounted on 15 x 7 Rally II rims. The tires are size P225/60VR15. I don’t have any clearance problems right now. As far as I know, the car is riding on a stock suspension, except that the coil spring pads in the front have been removed by the prevoius owner, so the front end may be sitting about 1/2″ lower than stock.
A: The 225R60-15 is a very close diameter to the G60-15 and F70-15 size. My 1967 has 255R60-15 on the rear and 205R60-15 on the front. I’m toying with the idea of going to 225R60-16 all around.
A: Make sure to get 15 inch tires to go on the 15 inch rims or\ replace the rims with correct 14 x 6 rims.
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Content last modified: January 26, 2014 at 5:41 pm
Q: Billing History Card Decode for Fiberglass Belted Tires
I just received my billing history from PHS. The tire protion reads as follows:
F70x14 RL FG $57.93 TMT $41.80 $2.93
What did these codes represent?
A: ….This is the breakdown for the type of Tires that were originally installed on your Firebird. (F70x14 Redlines, Fiberglass-Belted). The “TMT” is the Sales Code for that particular tire. The amounts listed are Tire Cost and Final Destination and Handling Charges.
The Fiberglass Belted Tires were NOT a mid-year upgrade in 1969; that happened for the 1968 model year.
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Content last modified: January 26, 2014 at 5:42 pm
Q: Vibration
I finally got my car out this summer and at about 50mph the car began to “resonate”. I could feel a vibration through the steering wheel and the pedals. Once I hit about 65mph, it went away and the car cruised great again. The vibration is there regardless of what gear I’m in and it doesn’t matter if I’m accelerating or braking. I drove the car around for hours reproducing the vibration and trying to figure out what it is and to see if whatever it is would let go on me. It did not get any worse or any better.
Based on my “testing” I don’t think it’s engine or transmission related. I think it’s probably something in the rear (driveshaft and back). I’m going to pull the driveshaft this weekend and have it balanced and get new u-joints installed as well. If that doesn’t work I’ll try getting the tires balanced and rotated. If that doesn’t work………..? Does anyone have Currie’s web address? 🙁
Ant ideas or experiences would be greatly appreciated.
A: check u joints first. i had a similar problem……..turnd out to be a loose u joint.
A: Check the tire balance. If you feel it more through the wheel it’s in the front. If it’s the whole car in general it’s the rear. Maybe a tire went out of round from sitting. At any rate check the easy stuff first!
A: As I was reading your description of your problem I was thinking U-joints. So, glad to see we are on the same page. The other obvious questions are:
-
The rotors. Is there any “pulsation” when you break at a slow speed?
-
Have you looked at the wheel bearing, front and back?
-
This may sound strange but check your shocks. If one has collapsed it could set up a resonance.
-
Could b flat spots on the tires.
A: And now the answer for people who, like me foolishly let someone else put on their wheels. About oh say 20 years ago, I took my car out of winter storage. For the winter, I removed the wheels and tires and put it up on blocks. In spring, a friend helped me mount the wheels. I took it out for a spin and had the exact same problem as you. Turned out my friend didn’t torque the lug nuts on one tire tight enough. I was darn embarassed when the local garage found them all to be loose. But hey… life goes on. I married my friend anyway.
A: I think its has to do with the tires but here is some extra stuff to look at. Two hard to track down vibrations problems I have had are the following
Bad motor and trans mounts (all 3 bad at the same time) and Bad rubber rear leaf spring cushion. This caused the rear end to move slightly out of line and float. It felt like the whole car was going to self destruct. (it was very inconstant) It was by dumb luck that I discovered the problem. Also if you body mounts are bad the car is less tolerant of bad tires.
A: It appears to be a simple wheel/tire balance problem. If in doubt about whether the tires will balance properly, look for a tire dealer with the newest balance technology, the load force variance type machines. They apply a road load to the surface of the tire while spinning the wheel/tire assembly, and can determine if there’s a problem in the tire (such as a belt shift or other imperfections), and even tells the tech if the tire needs to be indexed differently on the rim.
I worked at a Buick GMC dealer that had this machine, it was a Hunter 9000 I think, and we could condemn defective tires all day long on this thing. The down side is it’s labor intensive, and requires a tire technician who can actually think. If you need to index all 4 tires, that means attempting the balance, determining the index position, moving the assembly to the tire changing machine and breaking it down, moving the tire to the new index and re-inflating it. Figure about 2 hours shop labor for all four.
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Content last modified: January 26, 2014 at 5:43 pm
Q: Drum Brake to Disc Brake Conversion 1968
My 1968 firebird has drums all the way around, and I would like to step up to disc brakes ( at least in the front) without ‘Breaking’ the bank. I have thought about going to the local junkyards and looking. I read the FAQ, but I have only ever messed with drums and don’t know exactly what I need. Would you folks be willing to describe what I need to pick up off of the various doner cars? I plan on running 15 inch wheels, if clearence is a problem.
Also, I haven’t ever been to a junkyard. Any thoughts on what I need to bring? 🙂
A: To do a drum to disk conversion, you need the following:
-Disk brake calipers (use these as an exchange core for getting rebuilt units)
-Caliper brackets
-Brake backing plates/dust shields
-Disk brake spindles
-Front brake hard lines (sometimes the used stuff is pretty corroded. Might have to spring for new stuff)
-Master cylinder for disk applications (and booster if applicable) (use this as a core, or exchange you drum unit for a rebuild disk item. Most counter clerks can’t tell the difference)
-Disk brake proportioning valve
-Front brake flex lines and brackets (plan on buying new hoses. Don’t risk your life on used hoses of unknown reliability)
-Disk rotors (often worn beyond further machining, expect to buy new ones.
Some 14 inch wheels can clear the standard GM single piston brake caliper. I ran 14×7 Ralley 2s for a couple of months before switching to 15″ wheels. No problems.
Where can you find these parts:
1969-72 GM A-body cars (Chevelle, LeMans/GTO,Skylark,Cutlass) 1968-74 GM X-body cars (Nova,Ventura,Apollo,Omega) 1969 GM F-body
Earlier versions of these cars had a 4 piston caliper that is prone to rust, and parts are expensive.
You have not been to a salvage yard….Astounding!
There are two basic types of junkyards/auto recycling centers. The first is the full service type. You just go in to the office, tell them what you are looking for, and they pull it off the car. They may let you wander around a bit, but they do the work. Some of the better places already have the parts pulled and are sitting in a warehouse waiting for a buyer.
The second type is the self serve. Pick-Your-Part is the biggest chain here on the left coast. You bring your tools, pay the 2 dollar fee, and go hunting. You are also expected to remove the parts yourself, though it seems that the writers of Hot Rod and Car Craft seem to be able to get the hired help to do this for them.
If you go the self serve places, bring your coveralls, gloves, hand cleaner, and some band aids. You should also bring a spring compressor, since you will most likely have to pull the spindles off the car by removing the front springs. A big breaker bar and some good penetrating oil are also a must.
Once you get it home, you will need to evaluate the parts and see what needs replacing or reconditioning. You can find a machine shop to hot tank and/or beadblast the hard parts for you, or just clean them yourself. It’s always better to work with clean parts. Buy new bearings and seals, get some fresh brake fluid. The Ford Heavy Duty fluid is recognized as the best around of the DOT 3 type, and is reasonably priced. It has the highest boiling point next to the silicone stuff. New pads are also a must. Try and stay with high quality brand name products.
Used kits can be bought from places such as Firebird( and Camaro) Specialties for $350. They sell a kit with new or rebuilt parts for $795. I found that this is less expensive than buying used parts and replacing the above listed unuseable parts with new or rebuilt. Your call. I went the used part route, then compared my expenses to the cost of a new kit. I spent more, but got very anal on some of the stuff I did.
Alternative sources for used parts would be swap meets and some of the used Pontiac parts dealers found on the web or in publications such as “High Performance Pontiac” or “Pontiac Enthusiast”.
You may find that once you take the front end apart, you may want to do some additional work. Change the ball joints, replace worn tie rods and bushings, etc. It’ll snowball for certain.
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Content last modified: January 23, 2014 at 9:29 pm
Q: Disc Brake Conversion and Master Cylinder
I spoke with someone recently that added disc brakes to his 65 GTO. He did not change the master cylinder and the system still worked great. Said it would put you into the windshield without much effort. His has the single resevoir master cylinder running front and rear, same pressure front and rear. Is this alright?
A: My big concern here is that drum systems have a checkvalve in the master cylinder that maintains about 5-7-psi to keep the lips of the cups set in the wheel cylinders. In a disc system, this makes for a tiny bit of pressure that will cause wear and the resulting heat, not good thing!
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Content last modified: January 23, 2014 at 9:30 pm
Q: Caliper Rebuild
How do I rebuild my calipers.
A: I’ve had my calipers apart a few times. Rebuilding them is nothing more that replacing the seals unless the piston bores are corroded or damaged. Then you’ll have to have them re-sleeved (about – $35 per piston – expensive). I took them apart several years ago but didn’t replace the seals. Ever since I’ve had a problem with air getting into the system and having to bleed the disks about once a week. I never found a leak so this rebuild kit is an attempt to rule out the calipers. I’ve already replaced the wheel hoses and rebuilt the master cylinder, so I’m down to the calipers. I do have one question about bleeding the calipers to remove air behind the pistons. I don’t think the standard method of bleeding them like drum brakes accomplishes this. Does anyone know of another procedure?
A: I’ve always used one of these standard methods to bleed the calipers:
Two Persons – One pumps until peddle firm the hold, Other person loosens bleeder until pedal hits floor then re-tighten, Repeat until fluid is clear;
One Person – Use a 1/4 vacuum line attached to a piece of clear tubing, slip vacuum hose over bleeder and clear tube into bottle filled approximately 1/4 full of brake fluid, check to make sure the end of the tube is submerged in fluid, Open bleeder and pump peddle 4-5 times, Refill master cylinder and repeat until fluid in clear tube is clear.
Be sure the bleeder is at the highest point. After pumping a few times, try tapping the calipers lightly with a hammer. If there are any bubbles in the fluid, this will help float them toward the bleeder.
Another thing to check is the proportioning valve. On my 1969 convertible, the proportioning valve was sucking air in but not leaking fluid out. I bled the calipers many times before tracking down the real problem.
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Content last modified: January 23, 2014 at 9:31 pm
Q: Caliper Mounting
I am converting my drum brakes to disc on the front of my 1969 and after they have been installed the calipers are hitting the stabilizer bar any suggestions….are the calipers suppose to be mounted toward the front of the car or towards the back…maybe I have them on the wrong sides…..the assembly’s are off of a 72 lemans….
A: The back. You’ve installed them on the wrong sides.
A: I think you answered your own question, the caliper should be to the rear, Don’t fret though , I believe that all you need to do is remove caliper ,backing plate, caliper bracket and switch these parts right to left, The spindle is machined the same right or left this part doesn’t matter.
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Content last modified: January 23, 2014 at 9:32 pm
Q: Vacuum Line on Power Brakes 1968
Does anyone know if a 1968 firebird with power brakes had the vacuum line (that runs from the booster to the back of the carb) pass through a small clamped bracket attached to the throttle cable bracket? I have seen this setup on 1967 firebirds, and on a 1968 firebird in an old magazine article, but have not had any conclusive evidence that this was correct from the factory. Also, does the vacuum line leave the booster upward (12 o’clock) or downward (6 o’clock) as it makes its way to the back of the carb?
A: Maybe someone can confirm this info because I removed my 1968 brake booster a few months back, but I think that I remember it correctly. Yes, the vac line runs through the bracket. The hose attaches to the booster at the 9 o’clock position. I believe that the valve on the booster is pointing to the RH side of the car not up. The original vac hose is pre-formed. Hope that this helps.
A: My 1968 with power brakes is set up like that. Appears to be original way to receive vacum.
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Content last modified: January 23, 2014 at 9:34 pm
Q: Brake Components
What the heck is the difference or use for all the valve components for the brake system?
A: The round cylinder next to the master cylinder is the “METERING” valve, necessary for allowing the rear drum brakes to make full contact before the discs start to work, by holding back pressure to the front discs. ALL 69-70 disc brake GM cars have this.
The “PROPORTIONING” valve is a little SQUARE inline valve under the driver’s seat in the line going to the rear brakes, to slightly reduce the rear wheel braking on nose-heavy cars. On 1969 ‘birds, it was attached to the subframe’s left rail. NOT ALL 69-70 GM cars had this.
All 1969 and 70 GM disc brake cars have the “metering” valve, but not all have the “proportioning” valve.
All 1967 and later brake systems (dual braking, including 4-wheel drum brakes) used a warning lamp switch that also served as a distribution block, where the 2 lines in from the master cylinder become 3 lines out, one to the rear, and one to each front wheel.
In 1971, all GM disc brake cars went to a single component that combined the distribution block, warning lamp switch, metering valve, and proportioning valve and it was called (imagine this!) a “COMBINATION” valve. They were usually mounted on the frame and are hard to see from underhood.
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Content last modified: January 23, 2014 at 9:35 pm
Q: Front Valve (Round), Rear Valve (Rectangular)
I am confused my the nomenclature for the proportioning valve. I have seen and heard it called a couple different names. Which is correct?
A: To further clarify, I looked it up. The valve on the frame rail of V8/AC cars is referred to with two different names. The parts book calls it a “rear brake pressure proportioning valve”, and the illustrations catalog calls it “rear brake pressure regulator”. When I was in automotive tech school 100 years ago, it was referred to in textbooks as the “proportioning” valve, since it alters how much portion of the braking occurs at one end of the car.
The other thing I learned is the part number is the same for 1967 through 1969 Firebird, and that’s the ONLY car it’s listed for. P.N. is 3908326.
A: SO look it up in your Funk and Wagnall( any one remember that one?) In the shop manual its described as front brake metering valve(round one) and rear brake metering valve(rectangular one).Since inconsistencies are in GM nomenclature how can we expect anyone to come up with the same name. So I say lets just call it the round valve and the rectangular valve, because they both meter and they both proportion.Its all relative to flow vs. pressure which is relative to each other anyway.
A: The rectangular valve mounted on the frame rail under the drivers seat is a rear brake metering valve and is for V-8 A/C D.B. cars only. The round cylindrical one thats just under the master cylinder is the front brake metering valve and is on all D.B. cars. Later years(71 and up) used a combo valve which had all valving and brake warning switch in one.
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Content last modified: January 23, 2014 at 9:36 pm
Q: Metering Valve vs. Proportioning Valve
I’ve put ’72 LeMans discs and a power booster on my 1968. I’ve got a new propotioning valve and the “round piece”, both for a power disc 1968.
I’ve been told I don’t need the “round piece”, particularly for the later (’72) single piston calipers. I used the larger ’72 master cyl.
Anyone done this? Will I go skidding into a ditch if I do or don’t use the “round piece”? What do I call this insttead of the “round piece”?
A: The “round piece” is a proportioning valve (wrong – Read Next Answer). It’s located between the master calendar and the FRONT brakes. I had this discussion a while back and mentioned to the list that mine started to leak and, at the time, I wasn’t willing to pay $120 for a new one so I bypassed it. After bypassing it, I couldn’t tell any difference on dry pavement. However, I never tested it on a wet road.
The danger is if you get too much pressure to the front calipers, they may lock up on you before the rear brakes fully engage. Remember though, the engineers who designed the system was able to test the brakes on a machine the would tell them which brakes would engage first and by how much.
Years ago, Florida used to have a mandatory vehicle inspection. Part of the test was for brakes. They would make you roll onto a ramp and when the light turned “red”, you slammed on your brakes. These little scaled tubes would fill with liquid and based on the readings, you would pass or fail. I remember taking my 72′ Cuda’ for it’s anual inspection and it failed because the back brakes didn’t engage properly. I went out to the parking lot and back up and slam on the brakes to use the auto adjusters. It took several times to adjust the brakes tight enough to pass.
I went through this long winded explanation to say that the difference between passing and failing was unnoticeable in the vehicle during my daily driving. You, however, will be the judge of your system.
A: No, the “round piece” is a metering valve read on
Before they had the skidpads they had a treadmill kinda like a chassis dyno where you rolled onto a huge motor driven roller that propelled your stationary car to about 60mph and the inspector hit the brakes until the machine groaned and almost stopped. the balance between right and left was measured which was equivelent to a panic stop. They usually did this 3or4 times to really heat up the brakes. I welcomed yearly inspections, it kept the junkers off the road. I did fail in my street/strip driven 1968, it was running so rich it was burning everyones eyes the inspector saw this as a challange and went over my car with a finetooth comb. He even put a rag into the tail pipe blocking it off so he could hear any leaks in the headers/exhaust system. Fresh collector gaskets helped and couldnt find anything except the occasional loss of a high beam indicator. It was a pain to fix, never did find out why it would work sometimes, ran a new ground wire to the steel shell or the indicator bulb and left it that way for 20+ yrs.
Back to the brakes:
I posted something about rebuilding the metering valve(round thing) by using a rebuild kit for an import truck clutch slave cylinder kit. I found the box on the shelf( I guess I dont throw anything away) when I get the application from parts store i ll post it.
there is also a Proportioning valve on 67-9 cars that had a/c , disc brakes and a V-8.This slowed down the high pressure spike in the hydraulics to the rear as thes cars had premature lock up due to being nose heavy. It was a rectangular valve mounted under the drivers seat on the frame rail.
As for someone mixing up brake parts from one system to another, I would advise against it . If you want to change to disc brakes use all of the model specfic parts of that era. You shouldnt use the later combination valve with an earlier metering valve. the combo valve combined all of the metering ,proportioning and stoplight/bias switch into one. Its a much simpler set up but cant be mixed with other systems.
the 67-9 system is basicly the same on the hydraulic part but 1969 changed to the single piston calipers. So swapping 67-8 4 piston calipers with 1969 single piston ones isnt a problem
If you use the 67-9 bird system use all the parts from the same donor.A-bodies are fine donors for the brake parts but I prefer using Firebird(not Camaro or Nova) brake lines ,valving and switch. Also remember to replace the rubber hoses. I also use silicone fluid which when bled properly will outperform any others. A high performance car must have high performance brakes.
A: Thanks for clearing that up. I was wondering why my 1969 350/350 coupe with A/C had this device in the brake line under the driver’s seat and my 1969 400/400 convertible no A/C car didn’t. The thing that confused me even more was that I bought a complete 1969 Firebird disc brake system from a 400/400 coupe with no A/C and it didn’t have this extra metering valve under the seat.
So, since I’m adding A/C to my convertible, and the metering valve to rear brakes is not there, maybe I’ll eliminate the front metering valve to balance the system!!! 😎 Or, maybe someone on the list has an extra rear metering valve they can part with.
A: I don’t mean to beat a dead horse, but I was concerned about any possible confusion on the brake proportioning valve and it’s purpose in relation to the car CG and braking requirements. The valve was installed on V8 cars and Air equipped cars due to the front-heavy nature of these beasts. When brakes are applied firmly (especially front discs), the majority of the car’s weight not only shifts to the front wheels, but also puts the rear wheels in danger of losing traction and “breaking free”. Anyone who has been at the mercy of an uncontrolled spin can appreciate this. The proportioning valve simply limits the hydralic pressure to the rear lines so that the REAR wheels don’t lock up. Here is the exerp from the 1967 Service Manual Disc Brake technical overview:
“The Proportioning valve is used on disc brake cars with V-8 engine and air conditioning. Basically the valve works to limit hydralic pressure to the rear wheels. Up to 380-420 psi the inlet, or master cylinder pressure will equal the outlet or rear wheel cylinder pressure. Above this figure the outlet pressure will rise slower in relation to the inlet pressure. Consequently, above 380-420 psi inlet pressure, braking effect of the rear wheels is reduced in comparison to the front wheels.”
If you metered the front brakes you would only encourage the rear wheels to lock up…I know it was cool when Jim Rockford forced his car into a “power U-turn”, but you wouldn’t necessarily want it to happen unexpectantly with your wife and kids!
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Content last modified: January 23, 2014 at 9:38 pm
Q: Metering Valves Causing Brake Problem
I keep having brake falure but it appears that the master cylinder is fine and the problem is maybe with the metering valve. I have bypassed the valve and the pedal appears to be firmer. I’ll know in the next couple days if it is still working though (I’ll know when I go through the stop sign!).
If it turns out to be this valve, it’ll be the 4th one I’ve put on it. I bought it from a company in NH that sells them, rebuilt. The problems I’ve had are leaking fluid from the rear and sucking air into the system. Although the company has been supportive in sending me replacements, I’m tired of the failures!
Has anyone else had issues with the metering valve? Now that it’s bypassed, any issues? (The metering valve is a round cylinder – 3″ long, 1″ diameter – mounted under the left rear of the master cylinder. Used on 1969 AC cars. Lines run from the front of the master cylinder to the valve, then to the porportioning valve assembly)
A: Yes, I had problems with mine. Since I wasn’t ready to put it on the street but wanted the brakes to work when I moved it around, I, too, bypassed the valve. I made several test runs on the streets around my house and the system seemed to work fine without it.
There has been some F-List talk on this subject in the past. Some point to safety issues (i.e., if the engineers thought it was necessary then who are we to argue?) while others just mention originality. Personally, unless the car was placed on a very sensitive brake machine that would measure brake engagement times and pressures, I think you would be hard pressed to tell the difference when bypassed.
Something that I thought was a bit ironic… The engineers installed the metering valve in the front system be reduce the braking pressures and prevent the front brakes from locking before the rear brakes. But, if the car came with factory A/C, they had to install a second metering valve in the rear lines (it is located on the driver’s side frame rail, about the middle of the driver’s door) to keep the rear brakes from locking first. This was necessary because the A/C added about 200 pounds to the front of the car.
What does this mean?? Well… if you’ve moved the battery to the trunk, installed an aluminum intake, and a fiberglass hood, you just messed up your braking system because you just change the weight bias of the car by about 200 pounds… at least according to the engineers.
Now, take into account the hundreds of drum-to-disc conversions that I’ve heard about using Chevelle and Camaro parts and have never heard of any REAL problems AND, combined that with my Seat-O-Pants-O-Meter, I think the valves add little to the system. If anything, it’s just another thing to go wrong when you can least afford it.
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Content last modified: January 23, 2014 at 9:40 pm
Q: Brake Fluid Leak
Last week I noticed my brake pedal almost hit the floor before I had any “pressure”. I didnt’ find any brake fluid leaks anywhere except a very small trace under this “unknown” assembly. Rebleed the brakes and found the front left had alot of air in it. Drove it a week, then noticed this a.m. that there was a small puddle under the car. Traced it back to this “unknown assembly” I have power disc and the car is a 1969 This part is mounted onto the bracket that holds the master cylinder to the booster. (note: the master was just rebuilt a few months ago). There is one brake tube from the front of the master to this “part” and then a brake tube off it to the proportioning valve (rectanglar part). The part is round 2.5 to 3 cm diameter (or 1.25 “) and about 6cm long (or 2.5”). There appears to be a rubber boot on the end facing the booster. Fluid is possibly leaking from the front.
A: I had a weird problem that went on for years until I finally stumbled onto the solution. Fluid was leaking out the top back of the reservoir, emptying the front disk brake section of the cylinder. My front disk brakes would fade every week and had to rebleed. I had the master rebuilt and replaced the cap but the problem continued. No fluid leakage was visible on any other assembly or hoses (which I also replaced). Finally I rebuilt the disk calipers and the problem stopped. Air was getting in through the wheel cylinders and somehow pushing fluid back out the master giving the appearnce of leak there. Go figure!
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Content last modified: January 23, 2014 at 9:41 pm
Q: Brake Problem
Thanks for your input so far . I’m still undecided what to do. Is the master cylinder too small or is there a problem with the front calipers do you think? The brake pedal is going to the floor at the moment and the brake light on the dash doesn’t come on. With the two front flexible lines clamped off (near the calipers) the brake pedal is solid (it moves about 1″) and the brake light comes on when I press a bit harder. So that would indicate a problem with the front calipers? There are no visual leaks, but one of the members had fixed his problem by putting a kit thru the calipers when he had no visual leaks. Or is it simply not enough volume in the master cylinder? A local guy here quoted a couple of comparisons in Chev trucks he’d dealt with and it didn’t seem like the diameter of the m/cyl would affect things that much. The book does say 1-1/8″ though and mine is 1″. The way the brake warning light acts has got me too…… I have drums on the rear and the front are the 4 spot calipers that were an option.
How do I bleed those troublesome air gaps??
A: I still believe you have your calipers reversed from side to side, the left one on the right, and vice versa. I think the bleeder screws should be horizontal at the top of the caliper. If they are vertical, the end of the hole the bleeder screw is in may be at the top, but the other end of that hole in the bore will NOT be at the top! Therefore, big air pockets, which cause the brake warning differential light to come on when the pedal is pressed down hard.
If the bleeders are horizontal, maybe you have only half of each caliper reversed, so the air pocket is not happening at the caliper half with the bleeder, but at the half with the steel tube connecting from the other half. You have to imagine where the drilled holes lead to inside the calipers to get what I’m stating, or maybe just disassemble the calipers to see where those holes are relative to the piston bore. If they are reversed, you’ll be taking them apart anyway!
ps the size of the master cylinder bore is NOT YOUR PROBLEM!!
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Content last modified: January 23, 2014 at 9:42 pm
Q: Brake Pedal not Returning to “Resting” Position
What helps the brake pedal return to its resting position: pressure from the cylinder or a spring? Mine is having troulbe turning off the brake lights unless I lift the pedal with my foot after braking. Yes, I’ve tried adjusting the brakelight switch to no avail.
A: The brake pedal depends on the rod coming out of the booster/master cylinder to push it back up and turn off the brake lights. Try removing the pin that attaches the clevis to the pedal. Unthread the clevis so that you extend the rod lenght. Try a quarter inch at a time, reattaching the clevis to the pedal to see if it is coming up far enough to depress the switch. There is also a thin piece of metal on the pedal arm that contacts the switch. You might be able to bend this enough to contact the switch.
You may also check your master cylinder reservoir to insure you have enough fluid too!
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Content last modified: January 23, 2014 at 9:44 pm
Q: Painting Drums
I want to paint my drums to clean them up. What should I paint them with?
A: I cleaned them and then brushed on 2 coats of POR-15 and sprayed on a clear coat. They looked great.
A: POR-15 is a protective coating that also serves as a color and primer. It is made by restomotive. It is an organic rust killer that bonds with the metal and effectively keeps the air from getting to the surface. No air – no oxidation – no rust. There are several similar products but POR-15 is the only one I know of that “paints” everything the dame color. Most only turn the rusted areas black then you need to prime and paint. POR-15 comes in black gray and silver. you can brush it on it and dries with little or no discernible brush marks. They make a clear coat for it. I just bought a standard clear coat in a spray can that had UV protectorant element. I’m about to my chassis and engine compartment with it. You can find them on the web at www.por15.com. the stuff is non-porous so high humidity or wet weather doesn’t keep you from applying it.
I have had good luck with it. Be warned if you get it on you it is tough to get off.
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Content last modified: January 23, 2014 at 9:45 pm
Q: Disc Brakes and 14″ Ralley Rims
I am about to acquire (hopefully) a 1967 Firebird Sprint Convertible with the 14″ Rally wheels and fdrum brakes all the way around. Can the front brakes be converted to discs and still retain the 14″ Rallys? The Firebird FAQ mentions that they might not work
A: The real answer about 14″ Rallye’s and disc brake conversions is YES! Pontiac offered disc brakes from 1967 on, and while there were changes, these cars were also offered with Rallye II wheels. For a correct-for-year conversion would require the 4-piston fixed-position calipers, but the more roadworthy way to go is the 1969 Firebird/Camaro single-piston sliding caliper system. The same components were used on LeMans, GTO, Grand Prix, Cutlass, 442, Skylark, GS, and Chevelle from 1969 through ’72 (these are A-body cars); and a few Nova cars (X-body) from 1969 to probably ’74.
The best trick is to get the spindles, calipers and rotors plus the brake hose brackets from any of these cars from a boneyard or swapmeet. Then get a new master cylinder and combination valve from the ’71-’72 A-body cars. Trade up your core calipers for loaded calipers from your favorite parts store, plus new 1969 Firebird/Camaro front brake hoses. Get the rotors turned, or replace with new; get new steel lines from the vintage car suppliers to accomodate the 71-72 set-up, and build your system.
With it, you can have your clean stopping power and still fit most 14 X 6 and 14 X 7 Rallye II wheels on the car (there were a couple of wheel codes stated to be incompatible with discs). I’m not so sure whether Rallye I’s will fit, but they sure look great on a 1967 or 1968 Firebird! This group collectively can help you with the correct wheel codes.
A: I went with the Stainless Steel Conversion which fits just fine.
www.ssbrakes.com
Their good folks to work with, and they make the conversion with modern, easy to find pads which are still in use on today’s cars. Also, it came with a 9″ booster, prop valve, and timken bearings.
They have many kits… You might want to check out their site, as it is pretty good.
Another one which I would recomend second (kinda pricy, and pushy, but has some good products if you know what you need) http://www.inlinetube.com I purchased some SS Brake line from them… 18′ of 3/16 12′ of 1/4, 20 SS fittings, 2 unions, 2 T’s, and all the stainless clips for $145 including shipping. In my mind that was kinda pricy, but it beat playing around with bent tubing.
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Content last modified: January 23, 2014 at 9:47 pm
Q: Pulling Problem
f I am driving at a reasonable rate of speed, say around 60 or so, and suddenly have to brake, my car will pull to either one side or the other or fishtail to both sides. It’s really scary. I have replaced every conceivable brake part as well as the lower ball joints and idler arm. After several hundred dollars and several different mechanics I still have the same problem. Any help/suggestions/clues would be greatly appreciated!
A: That’s a tuff one. If you have the front drum brakes, they can be very difficult to get set up right and are not very forgiving. Find an old veteran mechanic that understands how to make them work right. One trick I’ve done to narrow down brake problems is to get on a disserted street or big parking lot and just stomp on the breaks and let the steering wheel go to see which wheel is locking up or which way it pulls. You can also press down on the parking brake peddle while pulling up the release handle. (Don’t forget the release handle part because it make for a real wild ride if you forget) If the car stops reasonably straight with the parking break on you can at least eliminate the rear brakes from being out of adjustment. Have you tried pumping the brake peddled before applying a lot of pressure to see if it stops straighter? This would indicate air in the system.
An old mechanic that I use to know after rebuilding front drum breaks would drive the car while applying the brakes hard and almost continuously until he thought they were seated in. This seemed to work, and his cars always stopped straight.
A: 1967-69 Firebird drum brake equipped cars have to be manually adjusted, particularily on the front; the rears are supposed to be self adjusting, but I always check them anyways.
Another thing to check is the tapers in the spindles that receive the balljoints, I once had a set wear out of round.
A worn out upper control arm bushing will also cause erratic steering as well.
Take the car to a good alignment shop and have a 4 wheel alignment performed. If you haven’t found the problem at this point, they should be able to find it for you. Good luck!
Any proposed updates, changes, pictures, and/or corrections, please use our comment section below (may need to click on permalink to access comments feature). Information is subject to change and offered as is without any warranties or guarantees. Please review our Term's Of Use for more information.
Content last modified: January 23, 2014 at 9:48 pm
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