choosing between the many ways to fill exterior trim holes

Question

Deleting exterior trim mounting holes on a car body means bodywork and paint. Before that happens, there are at least five possibilities, and probably more, for how the holes can actually be filled:

• Welding in a spiral of new metal to fill each hole -- never in order, to avoid warping the panel -- then grinding them down level. This seems to provide the best result for probably the most, and most skilled, labor.

• Banging each hole slightly concave and filling with a certain body putty. Despite an experienced body man suggesting this approach, I found that I couldn't hit the door panel hard enough, using a chrome ball bearing and a 2lb hammer, to make the impression.

• Low-profile hole plugs. They could be painted directly, for a studded one-color look, or else laboriously submerged in body filler.

• Standard body filler on its own seems likely to result in hairline fractures. Installed against some backing material, presumably glued to the opposite face of the exterior skin, would increase durability. I had some success with this approach on a previous vehicle.

• Brazing liquid metal, presumably around some kind of stopper, then grinding down to level. This approach was suggested in the comments.

• Lay epoxy-impregnated fiberglass fabric over the holes, use scraper to flatten.

I want to fill about 100 body holes, with modest expectations and a modest budget. Which approach would be best?

Answer 1

Personally i would be looking at epoxy resin, fibre-glass or similar.

If the panel or body can be rotated or oriented so it is near flat it will make things easier.

Epoxy has a number of advantages. It bonds well to many surfaces, and can be sanded and painted. Its less likely to crack than bondo/bog/filler and can be added in layers.

Welding or brazing would give a solid metal fill, but that would be time consuming and the there is a risk of warping the panel.

Using a punch to dent the hole slightly inward so it's not as flat will give more purchase for the resin. Another idea is to run tape along the inside of the hole then poke it a little from the outside so it forms a small pocket. Depending on the tape you could leave it there to help hold the resin in place. Ideally the resin needs more surface area to bond. If you can form a small mushroom head on either side of the hole it will hold better and last longer.

Answer 2

I'd plug weld the hole then dress the weld and lead load it or add a light skim of P38. If a job is worth doing, it's worth doing well. All other methods tend not to last as holes that have been simply bridged and filled without welding tend to "drop out" and show through the paintwork after a few months.