Floor pan plan of attack
 

I was a little surprised to find any rust under here but it was indeed there.

It's not the worst I've seen and after the work I've already done and the rest I still need to do, I'm trying to get out of this as easy as possible but do want to do it right.

I'm not much of a mig guy but I have one and I used one of these copper block things when filling holes in the firewall last week. It worked well but it's only about an inch square. Wondering if I should use it to plug those holes or bite the bullet and cut out all the rust? I'm not all that great with sheet metal and always end up blowing holes everywhere - the copper block helps me with that but welding in large sheet metal patches will be a bit of a chore.

What's your thoughts?

Re: Floor pan plan of attack
 

From the pics, it's going to be a lot less frustrating putting in a patch. The rust on the floor pan looks like it has thinned out the metal to the point where it will evaporate into thin air the millisecond it sees an arc. Trying to bridge to good metal, which could be inches away, will be a most painful experience. Get some good metal and go for it. Anyway, that's one take on this, good luck fixing her up.

Re: Floor pan plan of attack
 

If all those black dots next to the rust are holes then I'd just do the floorpans...not trying to patch it....

Re: Floor pan plan of attack
 

Oh no that's paint or seam sealer or something, if those were holes I'd do the whole pans. The only holes are those in the pic, but yes it's also got some thinning as ACK points out which is why I was hesitant to try anything other than cutting it all out which is also what I was trying to avoid.

Just a not so expected step in the middle of an engine swap project :)

Re: Floor pan plan of attack
 

Having just MIG'ed a bunch of small patches on my bed, I'll offer up the following suggestions, some that you may have already contemplated. These are based on the truck being a daily driver:

1. Looks like it's a small area, don't bother ordering a patch panel, use sheet metal and bend to shape
2. If you can't get the same gauge, go a little thicker, not thinner
3. If you get thicker metal, have it flush on the interior and protruding on the bottom. Stitch from the thicker material onto the thinner material.
4. Stitch weld both sides, not just from the inside, to minimize pin holes
5. When grinding down the interior weld, grind only the weld, don't hit the existing metal since it's already thin from the rust
6. Do minimal grinding under the truck, the extra material will add strength, plus who's going to be looking under there anyways

If you weld underneath, be careful, a glob of molten metal falling on ya' will be painful.

Re: Floor pan plan of attack
 

I am not very good at welding either as i am new to all of this restoration stuff but I have found that by cutting perfect squares out of the floor and then replacing them with the exact same size was the easiest for me. Since it was the floor i was not as tidy as it gets covered by insulation and then carpet. I was trying to maximize strength and durability.

Re: Floor pan plan of attack
 

I am doing a lot of this work now. The above statements are great advice.

Re: Floor pan plan of attack
 

I'm yet another amateur giving advice, but want to add to what Macdaddy1 said. When you cut and fit your patch, try to leave little to no gap between the patch and original metal. The less gap, the less likely you'll wind up with a bunch of blow-out holes to try to fill.