3 replies to this topic

[Digi1996]

Hi

I'm just wondering what's the easiest way to weld a front and back floor panel into a 1989 mini.

Cheers Andrew

[rally515]

Step 1: cut out old (roughly with enough material to trim back)

Step 2:mock up panel, scribe around the panel, trim to fit tight-ish (allowing for error still)

Step 3:get it fettled into place from trimming around (some prefer to cut the panel for only whats needed)

Step 4:tack weld in every 40mm or so

Step 5: seem weld between each tack alternating from one side of the repair to the other(as not to create warpage)

Step 6: grind back and redo any possible mistakes and prime/paint

[sonikk4]

If however you are not confident with butt welding then you can overlap the old panel slightly with the new one. Then tack weld in place then follow up by seam welding the complete panel. This is a must for either method to retain the strength and to pass the MOT.

[tiger99]

Unfortunately there is usually more to do, because the turned up edge of the floorpan forms the inner sill, and there is a structurally important bit that is inaccessible at the ends of the seat crossmember. The jacking point is in that area, and you may have chosen not to not use that, as many people do, but the sill box section is still vital to the strength and stiffness of the shell. Usually it means removing the outer sills and fitting new ones, which is not all that hard, just tedious.

 

However, if there was no rust anywhere near that area, and you are very sure about that, you can just trim the floorpans as required, and weld in accessible places. The easiest place to do the join across the car is under the flange of the seat crossmember, because as well as doing a but weld between old and new floor, there is the crossmember flange behind, and you will weld right through to that by leaving a very small gap between old and new floors. The extra thickness of metal makes burn-through less likely.

 

The rear floor pan is difficult because there is an internal subframe mount stiffner which joins the heelboard to the inner sill/floorpan, which is inaccessible without at least removing the outer sill, and if you leave that unwelded, structural failure is certain. Often the rear bins have to come out too.

 

Allow yourself at least five times as much time as you imagine you will need, and expect to find more rust that needs at least local patching, and you will not be disappointed.