Chassis leg replacement

[daveyl]

I'm going to do an engine change soon and thought I'd take the opportunity to replace the left hand chassis leg. And so i'm after some tips if poss.
I'm going to tip it on it's side and work from there.
1)Any tips for the leg removal (mine has been welded right along both seams)
2) I need to know how many holes to drill into it and how big the holes, so as to spot weld (it's a HALF leg).
3)Is there any need to brace the front of the car, to keep it's shape (adding extra support)?
4) which end to start welding and which method would you advise.

Any advise would be very much appreciated.

[chickenjohn]

Hi Davey,

the most important thing is to get the new leg in the right place- measure all mounting points several times- if you can, make up a jig to ensure the leg goes in the right place.

If the leg is welded along its length then it has been replaced before. You might find the tie plates and floor are rusty here, so be prepared to replace these as well.

As for spot welding a new panel in place, drill (or punch if you have a metal hole punch) 6mm holes at about 1 or 1 1/2 inch intervals along the mounting flange. Use self tapping screws to hold the leg flange tight to the tie plate/ floor and plug weld in the 6mm holes, use a higher setting on your welder and the "swirl" technique, start in the middle of the hole and spiral the weld out so that the leg is welded to tie plate/ floor.

Also, clean off the black paint between the surfaces to be welded and give it a coat of Zinc weld thru spray, them seam seal afterwards.

I would weld at intervals at various points, so you weld at one spot, then the other side, then the back, then front, don;t allow heat to build up at one point.

[daveyl]

Maximum thanks for that. Very, very useful.

[bmcecosse]

6mm holes ?? I thought 3 mm was the norm.

[Neil MG]

You might struggle to get a plug weld in a 3mm (diameter) hole! I know I would. Of course it will depend on the welder setting, but I find that 6mm or even 7mm works well.