I'm putting in a full cage in my CJ7 as a side project. I bought my CJ in virginia and the fenders and floors are nearly fully rotted. I'm planning on tying into the frame at all my six points but I'm not too confindent in the areas I need to mount through my body. So far I've patched with 16 guage behind the seats where the stock bar sat but the other four points will need some repair also of some sort.

Is using thick layers of fiberglass at mounting points a bad idea? I'm looking at 12"x12" squares over & under rotted body steel. I'm not doing competition but I'd like to be safe.

I say do it right, cut/weld and replace rotted sheet metal with new.

X2, cut out and replace, or buy a new body.

My bet is, if the stock/ current roll cage is held in flecks of metal between huge chunks of rust, your seat belt anchor tabs are held in by rust too. The door pillar hides rust and the floor seat belt on the outside is a little tab welded to the underside of the body.

If you want to do it on the cheap, you can buy body panels weld into the floor boards. Its labor intensive, but when your finished, it will be rust free and structurally sound. Toss some rattle can or truck bed liner on it and it will look all purty. Plus its going to compliment a nice roll cage when its finished.

Wally

Rockauto.com has wicked prices on CJ floor pans. If shipping wouldn't cost 8x the price, I'd have bought them for mine.

Is using thick layers of fiberglass at mounting points a bad idea?

Absolutely. If you use fiberglass in a body mounting area to "fix" rot it will never hold up. Plus add the fact that fiberglass is just a quickie repair when used for rust and will always come back to bite you later on. It will evetually allow moisture underneath it and then your rust problem will get even worse, and since it will be under the 'glass you may not see it until it's way too late. For your safety and the safety of your passengers, cut out the rotted steel and replace it with one of the many replacement panels that are available on the market. Not only will it look much better, but it'll be a ton safer, too.