I have a 1991 Firebird.. Love the car to death.. I have a hole that runs from the front left side of the floorpan (Where 3 pieces of metal join with seam sealer) Running about 1 foot back, and 2 inches wide.. Someone, within the last 5 years filled the original hole with expanding foam, and undercoated over it.. It seemed to get worse.. I saw a rust spot, and started poking with a flathead screwdriver.. Soon enough I could see floor..

My plan was.. POR 15 the rusty spots, use fiberglass cloth and POR 15 to fill the gap, and undercoat the top and bottom.. This should take care of the cancer.. I was also going to seam seal the area back up.. Now as far as structural support goes.. I have a t-top car, and this looks like it could hold some weight.. Should I invest in some SFC's? I know of a guy who makes his own, and installs for under $200..

 

You'd be better off cutting out the rusted portion of floor and welding some new metal in....Fiberglass and metal expand and contract at different rates, thus your 'glass patch is eventually going to work loose in spots...Then you'll be rusting out in areas covered with fiberglass and you won't see any of it till the floor is gone.... Connectors are a good idea on all the 3rd Gens, especially the rag tops and T-tops where the flex is even worse.

 

I wasn't using the Fiberglass resin, I was using the POR 15 in it's place.. It won't be as strong as factory, I also don't have access to a MIG, so it's all I got..

 

My IROC had some rot under the driver's feet, a section perhaps two inches wide by six or eight long. Several years ago, I used POR-15 products--paint, mesh, and filler--to effect the repair. After some cutting/trimming, I painted, completed the work, and painted a second time. Looks as good as new.

JamesC

 

Yea, it's good stuff, I originally did this on the under side when I had seen it last year while restoring the car.. I just figured it was the rocker panel.. I think a body guy filled it with expanding foam, and as it got older, it started to hold moisture..

Here's a couple pics of the damage, You can see some subframe in there too... I took out all of the foam, just a matter of waiting for it to dry (I already did the marine clean and Metal ready, last night)

 

I fixed it yesterday with the POR and fiberglass cloth.. I'll post some pics when I get home later today, It actually turned out pretty good..

 

dose that stuff you call por kill the rust or keep it from spreading. Ive got no floor pan left i just cut all my bad parts out. but im replacing the majority of it with new metal for the time being and fill the crap out of the rest. In some time im gonna replace everything on that side rocker inner bottom of the a pillar so on so on. but I have always done the long strand fiberglass method and never had no problems with it. but that por looks like its a tar based just saying how welll dose that work.