Car floor pans

[rockstarr]

Ok im needing to weld a floor pan on a pretty old Merc this week, having a fair amount of experience plating etc i havnt really done a whole floor pan as yet.

Am i to spot weld around the pan making sure all edges are flat, then use small 2inch seam welds 3 inches apart to start around the pan filling up all the gaps untill its complete?

No doubt everyone is blue in the face hearing about this topic but any advice would be great

thanks guys

 

[rtbcomp]

Sounds a good idea to me, but try to avoid overlaps, butt the two edges together.

A butt weld is stronger and an overlap would harbour moisture.

 

[malcolm]

I tend to try to replicate the original construction. For a floor that was originally spot welded I'd normally plug weld in the same locations (once I'd removed the old floor).

Plug welds should be stronger than spot welds, they are fine for the MOT where the original used spot welds. Also they will distort the panels and the door gaps less than seam welded joints.

This does leave a double skinned seam, so seam sealer is important afterwards.

 

[rockstarr]

cool thanks guys

 

[drjim]

I'm doing something similar on my BMW 635CSI. I intend to weld some long strips of steel onto the inner aspect of the sills to reinforce them, then spot weld the floorpan onto the reinforcements. May also need to rebuild the lower edge of the sill, but I am trying to avoid chopping the sill itself out.

I may use angle to replace most of the bits chopped out as apart from a big hole in the drivers footwell the rust is in the seam joining sill and floor.

I used an 8mm bit in a standard drill and reamed it along the seams to cut through. I did have the benefit of a plasma cutter (very cheap rehmann lg40 bought from mickjbriggs on the forum) which is very handy, and a full range of grinder accessories.

Spot/plug weld where there were spot welds originally, but you need to fully seam weld any patches in the floorpan itself.