Looking for floor pan replacement tips

[funknut]

Spent some quality time with my old and rusty floor pans. Tore most of the bad metal out, but still have a few sections that need to go (outlined in red). I will cut out the rear lap joint spot welds and remove that too. Ignore the apprentice marks and extra hole in the rocker, it's my first attempt at a job of this nature. ;)

I have L and R AMD replacement panels and would appreciate some tips/advice on where to stitch the new floor pan back in.

1) The front joint at the firewall looks fairly complicated, would it make sense to stop short of there and butt/lap weld across the front? Any advice for tackling that area would be great.

2) The outboard seatbelt anchor area seems fairly annoying, and harder to cut the floor pan away since it is right up against the rocker. Any advice there? The vertical metal is good, I could repair what I started pretty easily.

Thanks in advance.

 

[flypaper]

if it was me, I would just get rid of the rest of that front pan and replace the whole pan in one shot
and plug weld it back in.
looks like you are getting the hang of getting it out
which would be much easier and less headache then to splice over large pieces back in like that.

do the pans you have cover over what you cut away?
really it comes down to is cut away the bad
lay pan over and figure out where you need to trim it to fit
try to stick to butt welds only
lap welds are not good and they will leave a place for rust to hide.
plus you leave a lot to hide in mud
unless you really don't care..

 

[Rob'68Net]

In my honest opinion, it is always best to take the replacement panels to the factory seams and spot or plug weld them there. As for the front joint, yes I know how difficult it can be to go back to the original seam, especially without having the car on a rotisserie. Yes, you could stop an inch or so short of the original seam (as long as the original metal is good). I would recommend punching holes (or drilling) into the new pan with about 5/16" bit. Space you your holes about an inch apart. Make sure to clean all of the original metal with a wire brush, angle grinder, or both. You want clean metal to weld to. You are going to be lying the new pan over top of the existing front seam, the inch of original pan you left , and plug welding the hole in the new pan to the old underneath. Prior to welding I would recommend using a good weld through primer (aerosol can from auto parts store or welding supply) on all of the bare metal seams. Now set the new pan in place and make sure everything lines up correctly. Cut and trim as necessary. Now you can get yourself some self tapping sheet metal screws ( I prefer about an 3/4" long and about a 5/16 or 8mm head.) I would screw down the new pan to the old existing pan and then proceed to plug weld the holes you drilled or punched in the new pan. Make sure your heat is set high enough to penetrate the weld into the old metal lip of the original floor pan underneath. Continue to weld out your seam and then you can remove the self tapping screws and plug weld those holes one shut. This is not the only way, or "correct" way to do this. I am just sharing one way that I have done this.