[sir-gto]

Has anyone heard of frames sagging/bending simply due to age?? I don't believe my GTO has ever been in a serious accident but I'm thinking I may have a bent frame. I've only owned it for 13 years so I'm not sure if it's ever been in an accident or not, but based upon the condition of the sheetmetal at time of resto I don't think it's been in a collision.

Basically this is how the issue came up. The car has always sat 3/4" higher on the passenger side in the rear. I recently redid both the front and rear suspension, including polygraphite bushings, new shocks and coil springs. Passenger side still sat 3/4" higher. I decided to replace the original bodymounts. I took it in to have new bodymounts installed and they inspected the mounts and said the originals really don't look that bad and said that they'd be more than happy to do it, but didn't think it would solve the the ride height difference. They brought up the issue of a possible bent frame. One reason they asked is because they noticed a lot of shims on the drivers side upper control arm which were installed when I had it aligned a couple years ago. That along with the ride height discrepancy got them (and me) wondering about a bent frame.

I guess my question is can a frame sag or bend from old age??? They are going to do some measurements to try to determine if it is bent so maybe I'm jumping the gun, but I'm freakin out since this issue just came up and the complete restoration is basically done. Also, if it really is bent, is it easy to straighten a bent frame or am I better off looking for a new frame? Thanks!!

[runninwild]

First, don't freak out. Anything can be fixed, but you meed to find out exactly what is wrong. Can the frame be bent? Sure it can. Remember, the car is 43 years old. GTO's have a perimeter frame, and unless it is a vert, the frame is NOT boxed, except in the areas of the differential and the front end. The sides and the rear area are channel. The frame gains strength when attached to the body, but the sides and rear can be susceptible to twist. I have a '67 that I am re-doing now and I boxed my center section. Can the frame sag? Yes. I notice if I leave my car up on jackstands for a while, the door gaps will change, indicating a sag. All this doesn't mean that this is what is going on. Get under the car and look at the body mounts. If they are original, I can almost guarantee they need to be replaced. Mine were literally falling apart. Also the body mount holes in the frame tend to rust out over time as it is an area of entrapment for water. I repaired all of mine. The worst ones were the two just behind the rear wheels. They are brackets on the outboard of the frame rail on the weakest part of the frame. Take some measurements for yourself. Get a piece of angle and level it on the floor under the car and measure from it to the frame on each side at several locations. You are not looking for a specific dimension, you are looking for same side to side numbers. If you get very similar numbers from one side to the other from a level reference, then the frame is level in that area. You say that the rear passenger side is 3/4" higher. Higher than what? The frame, the ground, the tires? Measure between the body and frame at the mount locations. Make sure the mounts are tight. Sit down, if you drink have a beer or two and calmly think about what could cause your problem and how to fix it. If the frame IS bent, it CAN be fixed easy enough, you won't need a replacement.

[sir-gto]

Thanks. Good input. I'm going to see what the shop says, then get the car back and do some measurements for myself. The 3/4" difference is from ground to rear wheel well lip at the center of the wheel. Ground to wheel well lip in the front is pretty close from one side to the other. I believe they are thinking the sag/twist may be at the engine cradle. I guess I'll find out soon enough. Thanks again for the response.

[Cammer-6]

Only way to tell if the frame is straight is to measure and level it.
A good frame man can set it up on his frame machine and tell within an hour or so where it needs to move.
Are you sure the springs are all seated correctly?
The frames will sag in the middle and side to side at the front crossmember.
Proper way to gain that back is to spread the A arm mounts back out.
This is very easy with the motor out but almost impossible with it in.
Shop manual has all the measurements you need.

[sir-gto]

Thanks. I'm feeling much better about things. I have no issue pulling the motor to straighten the frame, I just didn't want to have to go to a new frame. I should know more about mine in the next couple days. Hoping it's not sagging at the front x-member, but thinking it probably is based upon all the shims required to align it.

[Cammer-6]

Sagging crossmember is a given with all these older models

[runninwild]

Originally Posted by Cammer-6

Sagging crossmember is a given with all these older models

Just think about the beating that these frames have taken over 4 decades, the weight of the engine, the countless applications of torque, bad roads, not to mention the deliberate abuse that muscle cars have taken time and time again, and CONTINUE to take. American cars of this era are always thought of as poor quality junk. Baloney! It was the consumer attitudes and lack of proper maintenance that led to this perception. My GTO will still be burning the hides long after my wife's Lexus is in the graveyard.

[irgoatmike]

I just bought upper control arm shafts at NAPA and all they showed available were the offset versions and the counterman told me it was due to most of these cars show some cradle sag and this helps offset the front end for alignment purposes. Seemed to make sense. irgoatmike