Bump and Measure

My friend just bought a ’75 T/A for a great price. We have come to find out that it was hit in the rear quarter some time in its life. There is a bunch of Bondo, and the deck-lid gap is tight on that side.

It doesn’t appear to have been too bad of a hit, but he is concerned that the chassis may be bent. Is there a way we can measure for that, short of having to put the car on a frame machine?

Thanks for any help you can provide.

Jim Armensaul

Via Internet

Melvin Benzaquen responds: Jim, this is a good question, as we get Pontiacs in my shop all the time that have been hit and not properly repaired.

There are a couple of visual checks you can make initially to see if there are obvious signs of prior structural damage. One is to look underneath the rear on either side of the fuel tank; you will see the unibody framerails that stop at the tail panel. These rails are square and the leaf-spring shackles ride on either side of them. Looking to see if the sheetmetal looks like an accordion. This would be within the first several inches of the rail, from the backside of the tail panel going forward. If either one of those rails are wrinkled, the body sustained an impact to the rear bumper area and may not be square.

Going further forward towards the rear axle, you also want to inspect the rail to see if it has been buckled or diamond shaped. This would indicate an impact in which the rail gave at a point further forward. This is typical of a fairly square and solid hit to the rear bumper, and it often happens in pairs.

You also want to look for rust, as that can compromise the structural integrity of the vehicle. If all of that looks good, take a magnet to the rear frame-rails and see if it sticks. I cannot tell you how many times we have seen filler riddled framerails covering up a major problem.

If all of the above checks out, open the trunk and take a look at the inside of the quarter-panels, tail panel, and trunk floor. Make sure you turn your head enough to look at the top of the quarters, as a high hit will ripple the quarter but not the framerail. You are looking for any evidence of ripples, bends, or covered-up repairs. Again, take the magnet and see if it will stick.

If that checks out, then look at the trunk lid. It is not uncommon for aftermarket trunk lids to have irregular shapes that make a relatively minor problem look like a major one.

Lastly, measure the trunk opening. I took a measurement from the trunk filler panel (the panel that goes in between the rear window and the trunk lid). There are two indentations on the panel that you can see when the lid is open. From the straight edge of the panel at the indentation on either side to the outer edge of the tail panel where the taillamp housings bolt up is approximately 21 inches.

I say approximately because there can be some minor differences from car to car. What you are looking for is that both front to rear measurements are consistent.

The other measurement I took was side-to-side in the trunk opening on the rail that holds the weatherstrip on the inside leading edge. Measure where that rail is still straight from side-to-side, just before the rail curves inward to make the transition to the tail panel. That measurement is 40 inches.

One of the above should show where the problem lies. Good luck and let us know what you find!