Patching floorpan mid section, Need help Options

[mikea100]

Hi guys,
I'm in the process of patching mid-section of floor pan under cross member on the pass side. Pix speak for themselves: general mark up, cut out pieces (IMG:style_emoticons/default/post-2-1117899824.gif), hole (IMG:style_emoticons/default/barf.gif), yellow patch, test fitting the patch.

I know that floor pan needs to be welded from under the car, but I don't have rotisserie so I will be welding from the top. My questions are:
1) Do I cut hole the shape of the patch or make patch the shape of hole. The former might me a little easier.
2) Do I cut exact shape and butt weld it or leave a small lip and lap weld it.

Any suggestions are greatly appreciated.

[Mikey914]

Honestly the easiest way to get it onto some good jack stands, drill out the spot welds (leaving in the cross braces at the seats just seporating them from the floor). You can buy a complete floor pan from Design Restoration, and if the back section is good, cut it down to meet up with the part of the pan you need to patch. Drill the holes for spot welds and weld back into place welding it in like you would tighten the lugs on a wheel, alternating across (so you don't heat up one section too much). You can use seam sealer to seal it back up. Much more work than a simple patch, but Design will have the cross braces too.

Just check out the back section behind the drivers seat in the firewall and inside at the floor. If you have rust there you may want to look at the entire floor board. If not you can just do a section like you have started.

[nathansnathan]

I'd separate the cross brace from the floor section on the donor piece and put the brace in first so you can back the welds. Then I'd cut the hole in the car to a more square shape, and then cut down the donor floor piece so that you can butt weld it in.

[mikea100]

Thank you guys. I did some grinding around firewall and found some rust, as Mark mentioned. However, its relativly small area. I actually have pass side floor pan and cross member from RD that I was going to use, but now I'm realizing that it's not feasable with my skill level and w/o rotisserie. That's why I'm trying to stick with smaller more managable patches. Can somebody estimate how much job like that will set me back (removing entire pass side and weld in new piece).

[rjames]

Grind down ALL of the rust first to see exactly what needs to be replaced. No sense putting in a bunch of small patches if one (or a couple) of big patches would take care of everything. Depending on what you have to replace, a rotisserie may not be necessary (nice to have, but not necessary). Clean the metal up well before you start welding.

I would also venture to say that if you are competent enough to do a small patch then you could also manage a big patch.

Since I had several small areas that needed patches in the rear part of the driver's side floor pan, I elected to cut the whole piece out and butt weld in one whole piece. No rotisserie needed.

Before

After