Floor Pan Patching
 

I'm patching my front floor plans ... only about the center 16" needs to be done, and up the firewall about two inches.

The method I'm using is cutting out the bad areas, then cut a matching patch from the panel with about 1" of overlap around the edges. I clamp the patch to what's left of the floor very snuggly and tack weld it around the edges.

Next I plan to cut both the panel and the existing floor a the same time through the 1" overlap a few inches at a time, tap the patch down flush with the existing floor in that section, tack it in place, move on to the next six inches? Should leave a decent butt joint, and if it can be cut at an angle it can even be a flush lap joint since the two pieces will lay together like this \\ .

Anyone ever done it this way before? Any tips, advice?

I've never done it that way but it sure sounds like it will work.

Waiting for some new blades for my air saw right now, I'll post pics if this method works. I hope to do some of the welding by TIG, other areas it will be impossible so it will be MIG.

I plan to do exactly the same for the quarter panel skins someone put on my '66. Instead of butt welding or flange welding, they overlapped the upper surface over the original. I plan to cut through both and peel back the overlap as I go down the panel.
That is, if I ever get around to doing anything at all with it...

floorpans
 

Check this guy out. At first I thought he was just going to lap weld. But in about 7 minutes in he shows how he minimizes the gap by angle cutting.

https://www.youtube.com/watch?v=_u31t13QO6A


Billk

Jeez, I wish floor boards were that easy to get at. But yes, that's the idea.

For as much as I can I'm going to try to use a thin kerf air saw blade ... it will be asking a lot of it to cut through two layers of 19 gauge, specially at an angle. I'll have to start the cut with a cut-off wheel.

I'd use the plasma torch but it will leave an oxide edge on the metal that I wouldn't be able to grind off before welding.

I think I'd rather use sheetmetal screws to hold the panels together but there's more than one way to skin a cat.
If I had to go back I'd just replace the floorpan section itself rather than patching.

If you mean the entire floor pan, didn't want to do that for the 10% of it that needs fixing. Entire area from front bucket bolts to the trunk is perfect. Didn't want to use the whole quarter pan sections because then you still have a seam on the firewall, trans tunnel, and forward of the bucket mounts, which just makes it a larger patch. Thought about screws but I didn't want to weld up the holes, takes 10 seconds to knock down the tack welds.

Couple of photos of the progress. Air saw cuts both layers pretty much as easy as one. Started with silicon bronze but that lays down too flat and doesn't give enough metal to smooth the transition. First pic shows a welded section between the surplus patch peeled back and the start of the cut.

Second photo shows around the corner next to the tunnel, started using steel rod, low amps and leaving a high enough bead to smooth the transition. Things are improving as I get the hang of the various techniques needed. I used a ratchet rod between the upper window frame and the patch to put some downward force on it to align it with the existing floor after making a cut.

Patch to floor fit is perfect ... almost too good, closes up a bit after welding and things get tight. Take your time and between tapping the patch down, and tapping the floor up you can get it so you can't even feel the seam.

http://forums.maxperformanceinc.com/...3&d=1595621609

http://forums.maxperformanceinc.com/...4&d=1595621616

Nice work.

Hopefully it will get somewhat better. Having to do some strange contortions to TIG weld it.

Looks great. Can never be too good. :)

Excellent.

Very nice approach on something that won't even be seen!

I'll see it in my mind if it's done poorly :)

Looks great! This is the method that was used to replace sections of the floor pans on my '66. It's the right way to do it. If you take your time and grind all the welds down afterward, it'll be invisible from underneath.

Very nice work. You should be proud.

I knew a guy that fixed a dent on a dash board...painted it...then wet sanded and buffed it.....and then installed the Padded Dash Pad ovah it .Some people have that issue...I guess

Yep, I've done the same thing, and proud of it .... it's nice to take pride in your work. I'm not doing this with profit in mind, doing it to be nice to the car that was nice to me for decades. Same way I treat my house, my tractors and my wife.

This guy is doing a lot of extra work. Interesting technique though.
Do Not use right angles if possible. They only collect heat as you start and stop welding, and that can make warping.

I share your opinion about the right angles vs. curved cuts. I know how heat will run to a corner (least resistance), so I consider heat transfer to adjacent panels whenever I am welding. If I have to cut a 90, that is where my last welds will be.