Re: trunk floor pan repair/replacement

Posted by Fish'n Jim On 2013/11/3 9:53:25

Out of necessity, I started doing fiberglass repair overlays back in the 60's. I grew up in the winter salt zone. There's 2 issues, you have to remove the rust area back to solid metal and have a rough surface ~60-80 grit for bonding. Epoxy resin is better but polyester works well, easier to sand. I wouldn't recommend sandwiching rust, unless you don't want it to last very long. Rust expands, pops the patch. Must be sealed from oxygen and moisture. Rust will continue once started. You can patch with steel and rivets just need to hammer and lightly grind so there's no bulge. Any attempt to just cover with fiberglass on anything but small holes will lead to thick filler requirement. Those are the easiest to cut out and weld anyway, so why? In the bondo queen era, they used to try to use screen and bondo to patch holes and it was an abortion. That's why I invested in welding equipment... Best patch life is around 5+ years depending on climate. I used to use galvanized sheet metal(before one sided) so the backside was protected. I recently repaired my p/u door, exposed to salt and it's been holding nicely in this climate. If you use rust preventatives, pre-layup, you may encounter bonding issues. Some coatings will adhere to primers, some won't, or the coating solvent may lift the primer. Lead has fallen out of fashion but quite effective and period correct.