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 - Brakes
Reference:
- 1968 Pontiac Service Manual Section 3 Page 3-5
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: 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: 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: 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: 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: 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.
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 22, 2014 at 11:58 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.
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 22, 2014 at 11:59 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: 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: 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: 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: 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: 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: 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!
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Content last modified: January 23, 2014 at 9:48 pm
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