C1 Panel/Body Shimming

[Bill B.]

I just need some reference point regarding "extreme" shimming. I am fitting a donor complete rear lower panel and both (one donor and the original) quarter panels. My bare frame is sitting on a jig and my body is mounted on top the frame. I shimmed each of the interior area mounts to exactly 1/2". I then went to the rear and could tell that it would have to be shimmed significantly higher to center my "railroad" style rear bumper brackets. In fact, it appears that the two rear mounts would have to be shimmed to about 1 1/4" for the bumpers to fit well. This 1 1/4" rear shimming seems to enhance quarter panel fitting and trunk lid alignment. Everything seems fine but that much shimming just doesn't seem normal to me. Real issue for me: what kind of shim gap is extreme?

Keep in mind, I cannot remove shims due to the construction of the "railroad" style brackets. They can be shimmed up at the frame but there is no adjustment down on them. Doors seem to fit well too?

[Wayne P.]

Re: C1 Panel/Body Shimming

What year are you working on? I have never heard the term railroad brackets.

[Bill B.]

Re: C1 Panel/Body Shimming

Wayne, it is a 58 and they used a one year only style three piece rear bumper bracket. The main support piece reminds me of a "railroad rail"- two channel pieces welded together with a long and short brace (recieves bumper bolts similiar to 59-60) bolted to the main. The main bracket is 2 1/4" tall and bolts to frame with two long bolts. In the end, it has to perform just like 59-60 brackets as far as mounting a bumper.

I can adjust the main horizontally about 1/2" fore-and-aft. The two bumper braces once bolted to the main don't really allow for any vertical adjustment. These two braces have horizontal slots so that the actual bumper can be positioned left and right however.

In the end, if I used zero shims on the rest of the car, I would still have to shim the rear body mounts up 1 1/4" so that my rear bumper can be recieved correctly. The only way I can see eliminating this excessive to me shimming is to shave more off of the mating line of my donor lower rear panel. But, it was cut exactly by using the cut lines from my original broken lower panel. When I bought this car, the body was off the frame so I don't know what she might have been. No shim markings on a rust-free frame. Anyway, wouldn't 1 1/4" of shims be pretty odd/bad?