Looking to replace the rear section of my floor pans. I noticed that when the car was built the back half of the rear floor pan (battery box area I think) is removed. Is there a reason for this like strength?
So my question is can I just trim off the front section of the aftermarket rear floor pan section and weld it in? Or is it best to use more of the front section of the pan and try to keep it original like when it was first built?
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The CMC/FF build manual has you cutting 10" out of the original floor pan (and tunnel). The cut they recommend is on the diagonal. You should be able to see how yours was done from underneath (or remove seats/carpet). I have seen more creative cutting (a stepped cut) and welding where the finsihed product is neater - but you don't see that area so not sure it is worth the extra effort.
https://www.youtube.com/watch?v=OMmf37sP5RU
Most new replacement pan thickness is thin - but welding and bolting perimeters make it strong enough.
Depends where your rusted out area is now. You may have an original pan where the battery acid destroyed the metal. Rear 1/2 replacement pan -
WOLFGANG posted:The CMC/FF build manual has you cutting 10" out of the original floor pan (and tunnel). The cut they recommend is on the diagonal. You should be able to see how yours was done from underneath (or remove seats/carpet). I have seen more creative cutting (a stepped cut) and welding where the finsihed product is neater - but you don't see that area so not sure it is worth the extra effort.
https://www.youtube.com/watch?v=OMmf37sP5RU
Most new replacement pan thickness is thin - but welding and bolting perimeters make it strong enough.
Depends where your rusted out area is now. You may have an original pan where the battery acid destroyed the metal. Rear 1/2 replacement pan -
The black replacement pan in your picture looks kind of what I have welded in my car. The pan replacement part I ordered has the a extra piece on the side for bolting it to the car. Do I need to remove that or can I just use it? It would save a lot of work.
I would use those side pieces as they make it stronger. There are smaller patch panels available. The one above would bolt to side of body and would be mig welded to tunnel, the back and to the front existing pan. Note - you need a 1" overlap on the diagonal cut.
These are the replacement pans that I am using they are from CIP.
VNG-95-10-76-3
VNG-95-10-76-4
Yeah today is the. Last day of their spring sale
OK, JB, now, after looking ar the CIP1 ad I better understand about the bolt holes. Yes, leave them on the panel - those are used to bolt the pan to the body frame so you’ll need ‘em. The rest of the install is the same welding that Wolfgang mentioned. Overlap intersections by 1/2” - 1” and weld them in place, then bolt the body sub-frame through the new floor pan holes along the outside edge
If the front floor half looks and feels OK and you just want to replace the back half or so, go for it. Remember to overlap the pieces and weld the seam on both sides (top and bottom).
Pic #1 - I would use the new panel, rather than trying to do intricate cutting and welding - make it simple.
Depending on how you remove the old floor panel (just cut the spot welds, leaving the tab along the tunnel in place to drop the new panel on to) and how long you cut the new section, it should just drop in there and you won’t have gaps when fitting the body on.
I used an air-powered chisel to pop the spot welds apart on the old panel-to-central tunnel, then tapped the long tab flat where the welds were and ground off any irregularities and the new floor dropped right in.
SO, on the new panel, keep everything from the rear edge forward as far as you want to go til you mate with decent original floor metal, overlap the edges and weld it in.
Gordon and Wolfgang thanks for all the advice, I appreciate it. Just had it sandblasted today. Now I can clearly see how the rear pans were installed.
On my rear floor pan install would it be better to spot weld the floor pan on the tunnel side and rear area or tack weld it in place and then run a continuous bead around? Do you also weld the rear floor pan on the bottom of the tunnel where it attaches to the tunnel lip too?
I tacked mine about every 6" with a 1/2" long weld. The new floor drops onto the flange/tab of the tunnel and rear bulkhead section so it more-or-less stays in place while welding. All I used was pressure from my foot - no clamps or anything. Make sure all your mating surfaces are flat(-ish) so they fit together without gaps - you may want to "adjust" a few spots as you go along.
Once all those tacks were done I went back and did a continuous weld in 2" increments every 6" to minimize warping of the floor metal. The result was what looks (sort-of) like a continuous weld, just done in segments. Warping wasn't an issue.
When I cut out the Delta-shaped shortening section I welded everything that was visible on both top and bottom. Did the welds on the outside of the tunnel, but didn't bother trying to get anything inside. Haven't had any issues with that, but for what you're doing I would just weld in the quarter panel from the top and be done with it.
Gotta love the smell of welding flux in the morning.........
