I also posted this on 3rdgen.org, so you may or may not have seen it. My '90 Firebird has bad T top seals, and subsequently, the water that got inside nearly destroyed my floor. I didn't really notice it at first, until one day I noticed the floor felt kind of soft, and out came the carpet to inspect:

 

Not only was the floorboard itself rotted, but a good chunk of the inner rocker as well, which can (and did, unbeknownst to me) affect the structural strength of the car.

 

Yesterday, we took on the task of replacing the floor. After much cutting and grinding, all the rotted metal is removed (except for the inner rocker) :

 

WIIIIILLLLLLMMAAAAA!!!! (cheap fred flintstone shot ):

 

I'm skipping a couple steps, for sake of keeping the thread a little shorter. here's a shot with the new board in place:

 

Lyle (a fellow mechanic) stitch welds the new board to the flanges:

 

Here's a shot of the completed underside, with a fresh coat of POR 15:

 

Lyle stitches the upper side of the board, and welds the seat rails back in to place:

 

Here's the completed board, partially coated with POR 15, and the rebuilt inner rocker:

 

6 hours total, the floor is as good as new! Changing the subject slightly, I've always had a problem with the driver door "dragging" against the rocker sideskirt when it opened and closed. To my surprise (and happiness), the door now works PERFECTLY! . I attribute that to the strength it regained from rebuilding the inner rocker.


My next investment:

New T Top seals!

 

The work looks great. Thanx for posting pics, I've always been interested in what that whole operation looked like.

 

Thanks, It really wasn't that bad with a stamped piece to match. Originally, we were going to fabricate everything we needed, but realized it would be a WHOLE lot easier to just get a complete replacement, and it was

 

Awesome! I really need to do that on my IROC.

Kevin

 

wow i thought my floor boards were bad but damn those take the cake. thanx for the step by step. was it alot of hard work at doing the floor pans? i look at mine alot and dont feel like i can get it done even though i am mechanicly able to do it.

 

It's time consuming, but you would be surprised at how easy it is if you have a pre formed piece. It's not very visible in the pic, but we left part of the old board attached, where there was good metal, and used it as a flange for welding the new board. That made it a lot easier. We trimmed the new board to match the old, so it was a good fit. After that, it was just a matter of welding and sealing.

 

you think you got a bad rotted floorboard.. you should see mine... i don't have any pics, but mine has a hole from in front of the driver seat up to behind the gas pedal and brake pedal, going the length of that area across... its baaaad... i'm probably going to need someone to weld it in for me since i can't weld

 

I wish I had some digital pic's from when I replaced my 91's floorpans(just insta-matics is all I have)
My son took one of me sitting on the ground with my upper body and head sticking through the drivers side floor(car was on jack-stands)
It was great for doing some re-wiring under the dash!!!
The job was time consuming,but not all that bad....Wheelwells and the spare tire area were a different story,not as much wiggle room!Good luck
Steve
I bought my stampings from Shermans and assoc.,nice parts in my opinion

 

Hmmmm, I look at these pictures and feel the nice smell of hot, fresh, welded floorpan!

 

Looks good man.Don't just love doing floor boards?Only thing i would add for anyone else thats going to do this or any other welding is use some welding primer. But just my 2 cents.

 

I'm really afraid of lifting up my carpet in my 85 T/A and finding something similar to what you had before.

I POR15'ed the underside of the floorpans just recently but I have yet to check the top of them. I hope that it isn't bad, but knowing my luck it probably will be almost completely rusted through.

 

Wow! My Bro needs that kinda work on his 92Z. Wish u could help him Good job must of bee a pain in the ***