Bent/warped A-body frame

[SShep71]

I can really use some suggestions, opinions, help, anything.
I am at the point in my body work in where I have to put the body back on the frame in order to cut off the quarter and roof then properly align everything. Currently I have both torque boxes removed from the car right now as I had to get replacements (the original ones were almost non-existent). I just finished welding in front floor panel patches, cowl to rocker reinforcements, outter cowl sections, and a few small patches to the general area. I did not weld the reproduction torque boxes on yet, because when I was aligning them and fitting them I was not happy with the way they aligned to the floor pan. They seem as if they are tilted, and not in plane. From here the plan was to lower the body back onto the frame, install the torque boxes in place with bushings. Then when all is tightened properly and adjusted best, tack weld the torque boxes in place so I can finish weld after I raise the body back off. That way I am ensuring that the torque boxes are aligned properly to the frame on which they, and the body bushings will rest.


THE QUESTION:
The problem I ran into, is that the frame of the 1972 GTO (which has lots of modifications to it), is preventing the car from sitting on the front body bushings. If I hold the torque boxes to the body, with the body bushing in place there is 3/4-1" of space in between the bushing (on the frame) and the bottom of the torque box (held in place against the body). It is almost as if the frame is bent or warped and now the body high centers on that spot. If I remove the mid bushings (under the floor pan brace) and lower the body down, the problem resolves itself. However, I obviously can't leave it like that. My best guess is that the frame is bent upward in the middle on both sides preventing the body from sitting properly. I have called around to every frame shop in the area and each one states the same thing "our machines don't go back to 1972", "we don't have anyone here that knows how to work on body on frame construction", or my favorite "we only do insurance work". I do have one more shop that seems to be able to help, but I have not gotten the time to take the frame over yet. In the likely hood that they are unable, or unwilling to try. Is this bent frame an issue that can be fixed? Can a frame shop pull down the center of the boxed frame? Will I have to cutout the middle section and start over? I can really use some ideas here, or feedback from someone with experience.

[raustinss]

Any pictures ?

[silvermonte]

When I did the frame off on my g-bodys olds I had sorta that same thing happen. I bolted the body back to the frame and everything was fine. I think with mine the frame was just flimsy enough to arc when not attached to the body. If I remember correctly I had around a 1/2" space on mine.

[cdrod]

I had similar issues with my '72 Olds 442 project. I did a full floorpan replacement complete with braces and inner rockers. I was vey meticulous about indexing the new floorpan to the to old body and to the frame but when I reunited the body and frame (working from the rear to the front) the center body mounts seemed to hold the body too high at the torque box mounts. I did some internet research and found a dimensioned drawing of the A-body frame, so I separated the body and frame to check these dimensions. I found that my frame was within +1/8" of the drawing dimensions. I was using repro rubber mounts and I did notice that the center mount location on the frame had a small ridge and the rubber puck was not sitting completely flat because of this ridge. My solution was to grind a little off the rubber puck to allow it to sit flat to the frame. This greatly improved the situation but it still seemed high in the middle of the frame.

I figured these cars weren't precision-built 50 years ago, and the rubber puck would easily conform to the deviation once everything was tightened up. So I put the body back on the frame and snugged up all the bolts and everything seems fine. I have attached the frame dimension drawing so you can look for any substantial deviations on your frame. It's also a good idea to measure diagonally across the frame sort of in an "X" pattern to look for horizontal deviations that may have occurred if the car has been in an accident. I hope this helps!

Rodney

[raustinss]

I was going to suggest googling that image , I'm still curious to what the problem looks like thou

[SShep71]

I thought about the fitment of the repro body bushings and the inaccuracies in the original construction from GM. Raustinss I don't have any pictures right now, I will get some posted as soon as I get to the shop this week and reassemble things. I want to at least check dimensions on the frame myself, and have the frame pulled square and all before I did any major body section removal. It just worries me that I didn't change the floor braces but I did change the front floor section and torque boxes, and if I install them incorrectly it will make everything else a disaster.

If I have to (and this is an absolute LAST ditch effort), I will take the body off the frame, and then swap it to the frame under my 69 and see how the fitment is. I know that frame is straight and flat, but that is a massive undertaking as I will have to transport the car to my shop and play the shuffle game. Which isn't impossible, I am just strapped for room already. What a headache this all turned into.

[raustinss]

Measure your frame yourself, you might just be able to straighten it out with a little ingenuity

[pitts64]

I would swap frames with a 68 to 72 el camino. That's why the 69-72 Pontiac Grand Prixs always handled so well... Model John really did meant something..

[raustinss]

El camino are longer , if your looking to swap for a different stock frame find a convertible frame .which I believe has the same factory reinforcement but has the right length overall, wheel base and body mount location .

[SShep71]

Not trying to swap out frames, I am trying to fix what I have. I already have plans to scratch build a frame for the "other" car. If It comes to it, I am going to just cut the middle out, align the frame and weld the frame to my big table. Il just recreate the center section of the rails. Until that happens, all hopes are on straightening this frame.

[dhutton]

Why do you think it is the frame? I would have guessed it is the body.

Don

[raustinss]

If I were a betting man I'd put it on a bit of both the body and the frame, they've both been "messed with" if I can use that term loosely. No matter what theres lots of ways to fix both

[SShep71]

I had originally thought about it being the body, I just didn't think there was enough of the body modified to make a difference. I am going to the shop this weekend now that I have some time to allot to it. I will post updates as soon as I can.