welding a new rear crossmember

I'm tackling the welding on the chassis in the next week or two, i haven't even done any before but I've been lent some space and equipment in a garage for a few weeks to get it done.

I've got one of those new cross members that just fits over the old chassis ends and welds in place.
How do i go about ensuring it lines up with the body, bearing in mind the rear tub isn't on right now? can i just clamp it to the chassis and expect it to sit right?


also, i'll be doing a few areas of patching and repairing, are there any golden rules or tips for welding the chassis?

Decent guide here: Rear Crossmember Replacement

I'd recommend making a jig like that. Whoever did mine in the past welded it on strong but not straight and it looks like I've had a rear-shunt!

The ones I've fitted haven't lined up with the holes in the tub. Best to find out early on and decide how you're going to deal with the problem. I was enable to enlarge holes etc but it was annoying - and leads you to think you've done something fundamentally wrong.

Work out how you're going to join it to the chassis - ie how much chassis you're going to have to replace. I assume its a SWB - in which case its quite easy to refabricate the whole chassis members with the body off. Don't forget any tub supports and pads before you finish.

When I did my LWB (chassis is a different shape at the back to a SWB and cross members only have extensions for SWB) I made up a jig to fit the 2 spring mount bolts (Top of shackle at back) and to engage with the tailboard mount hole which has a dimension on the diagram in the workshop manual.

On SWB's look for the straight line along the top of the chassis over the springs - I think its straight along that and to the top of the crossmember.

No body - make sure the length doesn't shift.

Trial fit before final welding may be a good idea. If you're repairing the main chassis try and do one side at a time so far as possible.

Take measurements before cutting the old member off or as suggested make a jig, then when you fit the new member run a straight edge along the body/tub supports and the rear face of the new cross member should be square to the straight edge. tac it up and recheck measurements and eye it up to the rest of the chassis. Good luck.

Ideally you want to fit the tub on and tack weld the new x member then remove the tub for better access. If this isnt possible, make a jig and bolt it to the rear supports and weld it to the chassis before removing the old one. There are 3 different forms of rear crossmember repair. The crossmember alone, rear x member with extensions and rear 1/4 chassis with spring hangers. Go for the latter.

If you have not done any welding before, on your chassis is not the place to learn,as those above say the time consuming bit is getting it fitted right,get all places to be welded shining clean.The actual time spent welding is not long and given that the crossmember strength is crucial it may be best done by an experienced welder.good luck.

Also take a look at www.mig-welding.co.uk/ a good welding tutorial.