OH NO! I found a hole in the floor of my 1979 Monte Carlo! I pulled up the carpet so that I could replace it and found a pin hole in the floor. This was very difficult, if not impossible, to see when I went over the car during purchase due to the location of the hole and the covering of it from the carpet. On the bottom of the car, the original transmission cross member had been replaced with an aftermarket one that supports true dual exhausts. The pin hole was right underneath the new cross member and covered by carpet so no light could pass through. When I removed the carpet, I was able to see light shining through this little hole. This caused me some concern since the area around the hole appeared to be all rust. I decided to see how strong the metal around the pin hole was so I punched it. Obviously my fist went straight through the floor, otherwise I would not be writing this!
On to the repair! I continued to push out all of the weakened and rotted out metal to the point where I could no longer take it out by hand. This is what I was left with.
So I used a Jigsaw with a metal blade attachments to cut out the bad metal and take it to a point to where I thought I could weld it back together with little fuss.
Floor Cut Out
I then took a piece of cardboard and held it with my hand on the bottom of the floor, underneath the car, and traced the opening with a Sharpie. I then cut this out and transferred it to a spare piece of metal that I had leftover from the Beetle project.
I attempted to cut this out using the jigsaw, but I did not have enough clamps to keep the metal from shaking so I ended up using a pair of tin snips to cut out the necessary piece.
Then I busted out my Clark 95 Mig welder (110V) and proceeded to weld in the new metal. I needed to shape the metal a little bit with some body repair tools so that it would match up to the hump in the middle of the floor but this was pretty straight forward, I just curved the metal using the pieces in the kit to the shape that was required. I am not a great welder (I actually suck at it!) but I was able to mate the two pieces of metal together.
Welds Before Grinding
Welds Ground Down
With a little bit of grinding and some rust inhibiting paint, I was able to make it look like I knew what I was doing. I also sprayed the rust inhibiting paint on the rest of the floor where there was some surface rust but the metal appeared to be intact. This was a preventative measure and was for peace of mind.
Painted Rear Passenger Side
Painted Rear Drivers Floor Pan
At this point in the repair I could still see some pin holes in the seams where I welded the two pieces of metal together. As stated earlier, I am a crappy welder. My solution to this problem was the Dupli Color Rubberized Undercoat. This stuff came out like mud and covered the pin holes that were there perfectly. This should keep water from getting into the car and starting the rotting process over again.
Floor With Rubberized Coating