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.
Body - Chassis
Q: Bushing Materials — Pros. and Cons.
I have heard a lot of debate for what type of body bushings to use. Can anyone give me a definative answer?
A: Bushing Materials– Pros and Cons.
NVH – Stands for Noise, Vibration, and Harmonics. Typicall things an engineer wishes to limit in a car design. Something a racer isn’t too worried about.
Rubber: Measured in durometer units, they can vary in hardness. Most stock bushings are fairly soft and are a compromise to offer reasonable handling but keep the ride relatively smooth. Remember that the factory had to sell these cars to both speed enthusiats as well as buyers who would be troubled by a harsh ride or NVH.The Ford Mustang especially was criticized for it’s harsh ride, and Pontiac sought to improve on that. The WS6 cars of later years (including the present) use a harder durometer rubber bushing to limit deflection.
The downside of rubber is that it decays and wears out. This is accelerated when the car is pushed very hard as in road racing or heavy drag racing.
Polyurethane: A relatively inexpensive upgrade that limits deflection. Users typically see an increase in NVH, but is acceptable to those more interested in performance driving. This is a synthetic material recently introduced into automobiles. Some of the big names in aftermarket suspension designers use this such as Saleen (Mustangs), SLP, Kenny Brown, Hochkiss, etc. Since deflection is the enemy of precise handling, limiting it is a good thing.
The downside of polyurethane is that it is very prone to squeaking, and sometimes bind. The squeaking can be eliminated or at least limited by modifying the bushing shells to accept a grease fitting and lubing them regularly. Another bad aspect of polyurethane is cold flow. It seems that after a period of time, especially under hard use, the bushing material may deform, slowly flowing like a liquid, ultimately needing replacement. Increased harsness can be expected. I put them in a 1970 El Camino, and it is noticable. Because it is much heavier than my Firebird, the weight of the car offsets the stiffer ride. I’ve also got them in the front of my 1986 Mustang GT ragtop. I find the ride quite acceptable. But that car also has a 6 point roll cage, subframe connectors, and Koni shocks/struts. On rough roads with potholes, it isn’t very fun. But that isn’t very often either. Maybe if I lived in New Jersey…
Steel/nylon or aluminum/nylon (Duralum): Absolutely a sure fire way to get rid of deflection. Companies such as Global West, VSE, and others tout this as the best choice for slot car like handling. Some of my road racing pals use these as well as heim joints in the suspension. These are usually dedicated race cars, but not always.
The downside is increased NVH. I know that Glen says it was either not increased, or at least tolerable. But I suggest to anyone considering these to try and get a ride in a car already equipped. You may like what it does for your car, but it will come at a price measured in increased NVH. Some can live with it and be very happy with the results. Others cannot.
What did I choose formy Firebird? Stock replacement rubber (TRW). My car is a convertible that had a lot of squeaks and rattles that I hoped to eliminate when I rebuilt it. I decided that I could live with the deflection in trade for a nicer ride. I’ve got other cars I can turn to when it comes to burning up the twisties.
You have to decide what you want to get out of your car, and what you are willing to trade off. Once you know that, the choices may become more clear.
Content last modified: January 20, 2014 at 9:48 pm
Q: Date Codes
While comparing the date code on my 1967 engine to the Fisher Body Tag, the dates are about three weeks apart. Should I be concerned my engine is not original even though it has the correct engine code (matches docs)?
A: As for date coding, the general rule of thumb for drivetrain components compared to Body Assy Date is anywhere from 2 weeks to 3 months. I’ve seen documented cases where some components were the week before Body Build and as distant as 3 months for things like an alternator. Generally, 6 weeks is the usual maximum. Keep in mind that there are no absolutes when it comes to date coding. Inventory Control 30 years ago was not like it is today. Most people will say that NEVER should a drivetrain component be dated AFTER the Body Build Date however, “never say never”. There have been special cases where the entire engine assy had a casting date after the Body Build Date. This could have been the result of production shortages and/or special build orders.
Also, remember that the Fisher Body Build Date on the firewall Trim Tag is not the final assy date. This Month & Week Code denotes the week that the body shell was assembled at Fisher Body. Again, in special cases, the body shell might have been pulled or put aside from the regular production flow due to a special order or part shortages. The Final Assy Date can be found on the Billing History. Listed as the “Invoice Date”, this is when the car left the final assembly line and was ‘certified’ to be shipped (bought-off). Once again, there could have been factors that delayed this date from being assigned to the vehicle or shipped. Part shortages, mis-builds, repairs would delay buy-off.
Your Firebird body shell was scheduled and assembled during the 4th week of October 1967 (23rd – 27th). This was the basic painted shell with glass, carpet, headliner, seats, some trim. From there,. it was transferred to the Final Assy Plant (Lordstown, OH) for Final Assy. This is where the front fenders, hood, bumpers, trim and drivetrain were installed. The Invoice Date on your Billing History would tell you when the car left Final Assy. The “WK” Engine Block you have (I177) was cast on Oct. 17th 1967. From there it was sent to the Engine Assy Plant and then to the vehicle Final Assy Plant where additional components were added to it before being installed to the vehicle. One could estimate that if it was cast on the 17th (Tues.) then it was probably not assembled until the 20th or 23rd. Figure another couple of days until it arrived at Lordstown for Final Assy into the car. In this hypothetical scenario, there is a chance that this particular engine COULD have been installed into a Body built during the 4th week of Oct. 1967. Variables would be how long it sat at the foundry, shipping time, scheduling and routing through selectivity banks, etc.
Often times, lower production vehicles were built according to a batch order. This would result in many of that particular model, color, engine being routed through production within the same week or period of time. This explains the Body Unit Number found on the Trim Tag and special in-plant codes found on the corner of the Trim Tag (usually found on Van Nuys or Norwood cars in late 1968 or 1969).
Hope this helped. As always, this information is from various sources and research others or myself have done. Exceptions usually DO exist to every rule.
Content last modified: January 11, 2014 at 8:39 am
Q: Body Bushing Replacement Procedure
Does anyone have a procedure for changing the body bushings? I’ve never attempted this and I want to try. There has got to be a painless way, and I’m sure you guys have tried everything. May main questions are, how do I lift the body away from the frame without screwing something up. What needs to be disconnected (Andy mentioned disconnecting the steering coupler). Do I need any special tools.
A: A way to change the radiator support bushings without disassembling the car. You can do the other 4 bushings while you’re at it.
The first step is to disconnect the steering coupler. This will make it much easier to replace the bushing closest to the steering box. The passenger side radiator support bushing will be much easier to replace if you pull the battery tray, which I didn’t do, but will next time.
Next, remove the radiator support bushing bolts, and the bumper support bracket bolts that connect the brackets to the subframe (2 bolts each side).
Next, chock the back wheels and jack up the front of the car, using a floor jack on the cross-member. Raise the car far enough to place jackstands at the very front end of the rocker panels. I used stands on which the piece that contacts the car is cast. Its footprint roughly matches the rectangular flat area on the rocker panel.
Loosen the four remaining subframe bushing bolts, but do not remove. Slowly lower the jack just far enough for the radiator support bushings to clear the radiator support. You may have to reposition the jackstands once or twice if the jack begins to move as a result of lowering the subframe. Be sure to get all the hardware out (there are various washers and such in there).
Install the new bushings and slowly jack up the subframe. You may have to coax the lip of the new bushings through the subframe holes. I used a small flathead screwdriver. Install the bolts, but do not tighten.
With the jack still supporting the weight of the subframe, replace the remaining bushings one at a time. This is fairly easy, especially with the steering coupler disconnected. Snug all 6 bolts, lower the car, and torque all of the bolts. This is the step where Hugo’s lift would come in handy, as you want to torque everything with the car on the ground.
That’s all there was to it. If your bushings are the originals, you should be extremely happy with the handling improvement. I sure was. Let us know how it goes. If anyone sees a step I forgot, please speak up.
A: I knew as soon as I clicked send I’d think of something. Rather than chocking the back wheels, you should raise the back end. This will result in the car being level once you get the front ends of the rocker panels up on jackstands. I used ramps on the back, but you could use a second pair of jackstands.
A: Well, I now know that it is possible to replace the radiator support bushings in an assembled Firebird. I ended up using Roy Lumsden’s idea of supporting the body at the front ends of the rocker panels and lowering the subframe on a floor jack. It worked like a champ! Thanks, Roy, for the idea.
While I was at it I replaced the body/subframe bushings as well. I had trouble getting enough clearance to remove the upper half of the bushing that mounts below the driver’s floor pan. I finally realized that I was fighting the steering column/steering box connection. When I was done I had to loosen and then tighten the bolts holding the steering column plate to the firewall in order to fix binding in the column (the new, thicker, bushing lowered the box relative to the body).
With all new bushings it is like a completely different car. I’d already rebuilt the whole front and rear suspensions, and replaced the shocks, which made for a much better ride, but the most dramatic improvements in handling were made by replacing these bushings and recently replacing the broken motor mounts. All the squeaks and rattles are gone and handling is great. Now I may not bother going to 15 inch rims. I just wish I could have done all the refurbishing together to get the full effect all at once!
Content last modified: January 5, 2014 at 4:38 pm
Q: Should I attempt body mount replacement
My 1968 f-bird convertible has deteriorated rubber body mounts. How hard of a job will it be to replace these? Are the bolts usually rusted to a point where they break off when you try to unscrew them? If any one has experience doing this please offer some advice if I am getting into a MAJOR headache.
A: I would definitely take a look to see if the perches that the mounts sit on are ruted away, or have sustained any cracks away from the frame itself. I did a frame off restoration on my 1968 bird and found every perch both rusted to the thickness of paper, and also multiple cracks rendering it unsafe unless rewelded and reinforced.
A: I did this on a 65 GTO convertible and had no problems, but this was on a rust free California car. If your car has extensive rust it may be harder. If you can get to it, soak the threads with WD-40 for a couple of days. When trying to break the bolts loose try rocking the wrench back and forth instead of applying brute force only to the “off” direction. Also try wacking the head of the bolt a few times with a hammer — this sometimes helps loosen things up. Just do it. You sure as hell won’t get it done if you don’t try. Good Luck!
A: mentioned by others, be sure to check the frame to look for rust problems before you stick in a bunch of new bushings. The jagged edges of a rusty mount will eat up a new bushing. If you want to repair the area instead of replacing the sub-frame, look for some large washers to “sandwich” the frame and tack weld them into place. To keep the body alignment close do only one side at a time. as far a rusty body bolts, I’ve seen them come out with only half the bolt remaining. Instead of WD-40 (which is a lubricating/penetrant) I would use something like “Liquid Wrench” (a penetrent) because its designed to cut through rust. Another trick if you have access to a torch is to remove the front seats and carpet and heat the captured nuts (located in the seat pedestal area) before you try to remove the bolt. Good luck.
A: I just wanted to thank any & all that posted tips on body bushing replacement. I just finished doing mine in polyurethane. It was the best small dollar investment I’ve put into the car so far. No more steel against steel squeaks when ya touch a fender. The doors appeared to have bad hinges on it before the job. Now they line up and close like new. My front clip even looks more in line. I even got the bumper aligned better. Anyway…………THANKS again!!!
P.S. On the frame connectors….. (1) the bolt on ones can be welded in (but you’ll never be able to change 4 of the 6 cage nuts that retain the leaf springs) (2) Manufacturer recommends that you crossdrill where the subframe meets the connector and bolt each with 4 1/2″ bolts (3) they won’t fit a convertible without a notch in either the connectors or in the offending brace under the car. I choose to notch the connectors and weld plate back in the hole.
Content last modified: January 5, 2014 at 5:10 pm
Q: Body Mount Replacement
How do I replace my body mounts
A: It’s not that difficult to replace of you have a hydraulic jack and a little patience and do one side at a time.
First break loose all four body bushing bolts. You’ll probably need a breaker bar and a pipe extension. The sub-frame bolts are located at the base of the firewall and under the front seat pedestal. If they look rusty, you can soak them in a good rust penetrate for a couple of days before you try to break them loose. You’ll need to remove the seats and fold back the carpet to soak the two at the back of the subframe. The firewall bolts/nuts are accessible from the engine compartment or from under the car.
After you’ve broken all four loose, put a piece of 2×6 on top of the jack to spread the load and lift the body at the front of the rocker panel. As you lift, you’ll see the frame separate from the body. You’ll need to lift the body to gain about 3/4 inch separation to R&R the bushings. You may have to use a pry bar to assist in the separation. That’s about it.
A: I changed mine, but had the front sheet metal apart at the time. I sprayed each bushing, bolts, and nuts with penatrating oil the day before. I also had the carpet (and interior) out of the car so I could get at the captive nuts under the seats for the rearmost bushings. The front 2 are actually in the engine compartment near the inner wheelwell. The bolts broke loose pretty easily with a breaker bar. I then cleaned and painted the entire subframe.
One difficulty, and it wasn’t that bad, was aligning the subframe up with the holes in the floor when putting it back together. It took nearly an hour to do this, since the subframe arms needed to be squeezed together slightly to match the holes.
If you don’t want to remove the sheetmetal, I’d loosen, but not remove the 4 bolts. Then working on one side, remove one bolt completely, leaving the other loose, but with the nut in place.
Using jackstands to support the body (place a wide piece of wood at least 2″ thick to spread the contact area between the jackstand head and the foor of the car),pull the bushing out. At this point, I’d try to apply POR15 or some other rust inhibitor to the subframe area and body where the bushing sits. These areas are prone to rust, and this is the time to stop or prevent it. Some cars may in fact need repair if the rust is bad enough. The new bushings, like the old ones, are 2 pieces, with one sandwiched between the body and subframe. The other half fits under the bolt head, on the underside of the subframe.
With the new bushing and bolts in place, but not tightened down, do the other bushing on the same side. Now do the same with the other side. Once that’s done, you can tighten all four bolts down. The key here is not to completely remove both bolts on the same side, or to tighten any of them until all 4 are done.
With the weight of the engine, and front clip sitting on the subframe, this may add some degree of difficulty to the job. But I’d try it myself. I had my car apart because it was being prepped for body work and paint. And it needed a fair amount of the front clip replaced anyway. Well, ok, the whole front clip got replaced. Plus I have the knowledge that I took care of all the details in that area.
Content last modified: January 5, 2014 at 4:42 pm
Q: Body Mount Alignment
Can you elaborate on what your steps were to replace the the body mounts? Did it affect the alignment?
A: the front bushing mounting platform (the thing the bushing sits on) there is a hole approximately 5/8 in is diameter. This hole lines up with an identical hole on the body. What they are there for is for body alignment when re-installing the subframe. All you do is take a piece of pipe ( I use a tire iron) and slide it through both holes (the frame and body holes) and make sure that they are vertically aligned.
If your replacing the bushings with out removing the subframe, the above procedure won’t be necessary. By only replacing one side at a time AND with front fenders bolted in place, the frame should remain in the correct position.
Content last modified: January 5, 2014 at 4:45 pm
Q: Radiator Bushings
How do the radiator bushings fit? It’s a standard two piece rubber bushing, one half of the bushing has a metal sleeve, the other half is just rubber. Does the metal sleeve half fit in between the frame and support? Does this bushing use a large metal ‘washer’ like the body mount bushings do?
A: You’ve got the right idea. The bushing w/the metal sleeve fits between the frame and radiator support, with the sleeve protruding upward. The other rubber piece sits on top of the support, over the sleeve. This half of the bushing has a large hole on one side, and a smaller hole on the other. Place it with the large hole fac- ing downward. Two large washers are used, one on top, and another on the underside of the frame. In addition, you should have a med- ium sized washer, a lock washer, and nut. Push the bolt in from above with one of the large washers. Use the remaining washers on the bottom.
Some repro bushings are a little large for the radiator support hole (at least it was on mine), so some triming and filing may be required. In addition, the bolt was short. The GM bushings are correctly sized, and with the correct length bolts.
Content last modified: January 5, 2014 at 4:47 pm
Q: Chassis Paint
Is the firewall the same color as the body? If not … does anyone have the paint codes for the (various?) colors (black?) needed for the subframe, firewall, inner guards, radiator support and so on? I have decoded the cowl tag and the color is D/D ie Alpine Blue upper / lower
A: Fire wall is semi gloss black. Paint from AMES or Year Ones is excellent.
A: I pulled this out of a 30th anniversary Camaro magazine but pretty sure it also applies to Firebird:
Egg shell black lacquer for: Firewall, Inner radiator support, and other engine compartment sheet metal:
PPG (Pittsburg Paints)
2 quarts “mixing black” #386
1 guart “universal flattening agent”
One quart “mixing clear” #310
Use PPG #DDL-16 or DuPont #3608S
2 quarts “mixing black” #406
1 guart “universal flattening agent” 850
One quart “mixing clear” #465
For the under carrage, Frame and suspention use enamel (easier to clean up for show):
PPG Delstar or Dupont Centari
3 quarts mixing black (sometimes called “strong black”)
1 quart flattening agent
Use PPG DTR601 quick dry reducer
The above is for the “purists” who like the correct shade of black. I’ve had good luck with three parts cheap chassis black and one part universal flattening agent. Comes out semi flat and looks great on the firewall, and chassis.
A: You can contact the paint manufacturers on line, give them the color and year, and they will give you the codes or equivalent in base/clear. Or you can contact via 800 numbers. They are very helpful.
Content last modified: January 5, 2014 at 4:51 pm
Q: Undercarriage Painting
What is the absolute most rugged and above all, correct paint for the underside of my 1968 bird??? I’m talking frame, floor boards, front wheel wells and firewall. In the recent issues of HPP, Jim’s 1967 was featured with talk about using PPG products and the various gloss levels. That’s great.. But which PPG products??? Anyone know? I want mine to be correct and I will use a spray gun rather than a spray bomb. Your helpful hints appreciated as always.
A: Here is what I got from a (gulp) Camaro restoration article. I can’t imagine the Firebirds being different:
Firewall, inner radiator support, and othr engine compartment sheet metal:
– two qts “mixing black” #386
– one qrt “universal flattening agent”
– one qrt “mixing clear” #310
– use PPG #DDL-16 quick dry thinner or DuPont #3608S.
Undercarrage, frame and suspension:
Egg shell black enamel;
– three qrts mixing black
– One qrt flattening agent
– use PPG DTR601 quick dry reducer
Enamel is used for these pieces because it’s more durable than lacquer and will quickly wipe clean for “showing of” purposes.
A: In this day and age Im surprised that anyone would use laquer or enamel for a place like the underside of the body. There are many good urethanes that are far superior to enamels or laquers, for chip resistance,and general wear and tear. Most of these urethanes have flattening agents to get the proper dullness or gloss. You do need to play with mixing to get the proper amount of flattner vs. gloss. Anyone tried the POR-15 semi-gloss? Curious as to the correctness of the gloss. Also dont forget to do this before you paint body so you can get overspray on the rockers and into the cowl area as the factory did. Carefully mask the frame and leaf springs, and all cables lines etc. Just remember how this was all done at the factory.
Content last modified: January 5, 2014 at 4:55 pm
Q: Underside Painted or Coated
Here’s one for you old guys. When you bought a car back in 67-70 was the under side painted/coated? Were all these cars rolling off the line with shiny silver bottoms? I seem to remember my Dad talk about the dealer undercoating the car as an extra. And it was that black tar like stuff; cause that seems to be whats on the under side of my convertible.
A: As far as the underbelly of these “vintage” cars, they were painted. Undercoating was a dealer installed option. The owner of the car I just finished restoring opted to do without it.
Because of the superior coatings and galvanizing, the new cars actually do better without it.
A: My 1968 Sprint Bird came from dealer with an undercoating and a paint treatment called “Ming Paint Treatment”. ( and we think of dealer add ons as a new thing) The undercoating was /is a yellowish waxy paraffin substance that looks like beeswax. It was easily removed with lots of rags and mineral spirits.(better than scraping). All areas other than overspray of body color would be semi-gloss black. As far as I know the factory didnt offer rust prevention/undercoating until the 80s. A friend bought a T/A new in 78 and tried his darnedst to order car with it. He ended up going to Rusty Jones and having it done.
A: I will clarify this myself before someone reads it wrong.. The undercoating at each wheel well that is neatly masked off when sprayed on is factory. This was used more as a sound deadner that a rust proofing/ undercoating. Ive heard some people say they scraped it off, but if its not rusted around it ,so as to get underneath then I would leave it alone. It is hard to duplicate the texture of this sound deadner and this stuff really works good. As far as the rest of the underside of car factory didnt offer it. An option on the GTOs was to delete sound deadner and body dum dum. It saved alittle under 100#s and was mainly for drag racers..
Content last modified: January 5, 2014 at 4:57 pm
Q: Undercoating Removal
I’ve got the Black tar like stuff on the bottom of my 68, I’m trying to get it off so I can prime the under side. It’s sticky and a pain to removal. Anyone have any tips?
A: Sounds like the undercoating I had on my convertible. The way I removed the junk was to heat it with a propane torch just until it becomes soft. I would then scrape it off using a cheap scraper. I rounded the corners of the scraper so I wouldn’t gouge the metal. When I heated the undercoating, it would peel off in strips. Once I had removed the most of it, I used a Scotchbright scrubbing pad, mineral sprits, and a rag. I feel for you. It’s a nasty job. Be sure to wear gloves and goggles.
Content last modified: January 5, 2014 at 5:02 pm
Q: Subframe Differences Between Years
Guys do any of you know if the subframe up front is the same on a 1968 as a 69???
A: There are some subtle differences in 67-9 sub frames. Functionally they will interchange. All three have differences in the steering linkages not just 69.
Content last modified: January 5, 2014 at 5:04 pm
Q: Subframe Difference from 1967 to 1968
I know that the 1967 and 1968 subframes are different. Can someone tell me something I can measure to tell which year I have. My wife’s bird had a 1968 nose on it when we got it and I wonder if the subframe was changed as well.
A: You don’t need to measure anything. The easiest way to tell is the steering linkage. The 1967 Firebird was the first and last year to position the linkage behind the front wheels instead of in front.
Content last modified: January 5, 2014 at 5:12 pm
Q: Alignment Specs
I have had a lot of questions about the alignment specs for the 1967 – 69. Does anyone have this information in their resources and would like to share?
A: It’s right there in the 69 Factory Service Manual, page 3-18.
Toe-in…………1/8″ to 1/4″
SAI……………8-3/4 degrees with 1/2 degree camber (steering axis inclination)
Toe-out on turns..2 degrees, measured in left to right direction of toe-out at 20 degrees turn of inside wheel.
Caster and Camber specs were listed by the aftermarket (like alignment equipment manufacturers; Hunter etc.) to have a range, like caster was +1/2 degree, plus or minus 1/2 degree; and camber was 1/4 degree plus or minus 1/2 degree. These were prone to lesser technicians stating “good enough” when the car was wearing tires and pulling to one side. Evenly matched settings from one side to the other are best, with a slight offset to compensate for road crown in some parts of the country, where the road shape pushes the car towards the ditches.
When I used to do alignments (and I’ve done probably thousands) during the 70’s when people were putting radial tires on cars that came with bias or bias/belted tires, the industry standard was to add 2 degrees of caster to whatever the specification was. It is not usually possible to get 2-1/2 degrees of positive caster on most 67-69 F-cars unless you add offset control arm shafts, but anything over the 1/2 degree is very helpful on radial tire, especially with wider tires. In addition, keep the camber and toe-in minimal with wider tires for prolonged tire wear life.
Content last modified: January 5, 2014 at 5:14 pm
Q: Subframe Alignment
I removed my front subframe assembly to repair the bodymounts as the holes had rusted out to more than double their original size. I patched them with body mount repair plates from Performance Years. All looked good before welding, however I must have screwed up after I took my measurements because the front mount holes are now about 2/10″ length wise off each other. Didn’t notice that it had move before I welded and now I figure it out after the frame has been primed and painted……Can I get away with this small inconsistency?
A: Use two 3/4 in diameter rods to line the body with subframe before modifying any mounts. There is an alignment hole on the lower cowl section that this rod will fit into and should be perpendicular to frame if aligned right.This can be slid up and into the cowl from underneath the car.
Content last modified: January 5, 2014 at 6:32 pm
Q: Wheel Well Plugs
I need the part # for the wheel well plugs. I noticed one of mine was missing during my undercoater removal. The under coating was so thick, I didn’t know there were plugs there till I hit them w/ the screw driver. Maybe that missing plug allowed all the garbage out, because my rockers are in great shape.
A: The part number for the wheel well plugs is GM#0480-5844. The only difference between the original plug and the new plug is the original had the part number molded into the back side (that’s how I found these), otherwise, they are identical.
Content last modified: January 5, 2014 at 6:35 pm
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