Body Repair -how should the UNDERSIDE of the body be correctly finished and restored?

[Scott S.]

There was damage in two areas of the left-hand rear of the car. Damage to the left-rear tail light area where the bumper curves around the edge of the car, and damage just behind the rear left wheel. I don't know how the tail light area was damaged, and the previous owner (1972-1976) didn't know anything about it. The panel behind the left rear wheel was damaged in 1980, when my Mom was backing the van out of the driveway. The Corvette was parked next to the van, and as she turned while backing out, the RF bumper of the van hooked inside the LR fender panel behind the wheel, pulled it outwards away from the body, and broke it.

Repairs were done at the time, and looked good on the outside after paint, but the underside was a mess with a sort of fiberglass reinforcement bracket added to the area. The old repair job was removed, and the fiberglass has been repaired to appear as original.

The areas that were worked on are clearly distinguishable from a coloration and texture standpoint. What can or should be done in order to restore the appearance on the underside as original?


Picture 1: underside view of repair to driver side rear panel
Picture 2: underside view of repair to driver bumper corner area

Picture 3: underside view of undamaged passenger side for comparison

[Chuck S.]

Re: Body Repair -how should the UNDERSIDE of the body be correctly finished and resto

The only way to get the color the same is to use tinted resin that matches the color of the original resin. If the color is truly gray as it appears in the photo, you would have to grind out the repair and do it again to get the color right. If the gray is from finishing scratches (black fiberglass appears gray when rough sanded), you can use progressively finer paper to smooth and polish the surface. I have even painted on clear resin to smooth the surface and bring back the black, but that WON'T WORK if the color is actually gray.

The inside of the panels around the rear wheel well area will likely have a rough texture that will be next to impossible to duplicate without risk of damage without practice...it is a very rough texture. The factory actually sandblasted the inside surface of the fiberglass to insure good adhesion.

The close-up appearance of the original fiberglass mat will be impossible to duplicate because commercially available mat is not manufactured in the same way anymore. The original mat had long, curvey, hairlike fibers, and the new stuff has fibers that are straight, but randomly oriented. This difference will not be obvious unless your eye is very close to the repair; depending on the available light, I would say about 2-3 feet.

In my opinion trying to get these repairs to look exactly original will be a futile use of time and resources. The large panel repair looks unusually good from the back side; you might want to confirm the inside surface around the bumper attachment point is smooth, and remove those stripper stains that ran down through the openings.

The one thing that you have going for you is the large gray repair is in the wheel well area, and can be concealed by a little "careless factory" black out, then undercoating. You will want to be sure all finishing scratches and marks are removed before any area is "black out" painted.

[Scott S.]

[Dick W.]

Re: Body Repair -how should the UNDERSIDE of the body be correctly finished and resto

Scott, I guess the statue of limitations has expired, so here is what we did. I color matched paint to the fiberglass color and just fogged it on so as not to get a slick shiney surface. We restored several cars that had previous damage, and the owners did not see the need to re-repair those areas. It always worked and never was called on the judging field

[Scott S.]

Re: Body Repair -how should the UNDERSIDE of the body be correctly finished and resto

Scott, I guess the statue of limitations has expired, so here is what we did. I color matched paint to the fiberglass color and just fogged it on so as not to get a slick shiney surface. We restored several cars that had previous damage, and the owners did not see the need to re-repair those areas. It always worked and never was called on the judging field

Hi Dick,

I was wondering if something like that might work, either dyeing or staining (somehow) or lightly painting the underside fiberglass in the repaired area. Glad to find out you've had good results, thanks very much for the reply,

Scott