[dwdw]

I am about to fit new rear crossmember & have plasma cut the old one off. have searched forum but cant work out how much of the original chassis I leave. Does the old original box section have to slide inside the new box section. I know the extension pieces have to cover the old chassis rail box section but not sure if the old metal has to go inside the new or does it butt up against the new? Thanks in advance for any help here.

DW

 

[lynall]

If its a generic replacement xmember with extensions, I think the old goes inside the new.

 

[jimwyllie]

When I did mine a few years ago the new crossmember was slightly flared to fit over the old chassis box section. Overlap was about 3in or so.

 

[dwdw]

thanks for your replies, the extensions fit over the old box section but what I dont understand is does the old box section have to go down inside the new square section??

 

[dwdw]

on this pic will the old rail go into the new or butt up against it?

 

[jimwyllie]

The new crossmember will be slit on the four corners of it box section. The old box section should go into the new as far as the end of the slits. You can then clamp the new one up and weld along the slits as well as at its end. Hope this is clear

 

[Al2O3]

Your major controlling factor will be getting the lugs to match up with the end of the tub.

 

[Southernlandy]

This is how I did mine:

 

[Al2O3]

Cracking.
How did you gauge the length to get the lugs to be in the correct place for the tub? Of course dwdw may just have his propped up.

 

[Southernlandy]

Made a jig using some aluminium and bolted the old to the jig and the jig to the tub supports, cut off old one and bolted new one to jig.

 

[Al2O3]

QED

Clever lad

 

[dwdw]

As Al2O3 said I found that the corners were holding it off & needed shamfeering to get a good fit. Despite measuring twice it still needed offering up & fine adjustments made with grinder. Now its welded in place I can see that there is no way the old box section will go inside the new box section. Thanks everyone for your time.

 

[Al2O3]

I'm confused, mate. You haven't welded the 4 corners of the new cross member legs together before sliding it on to the cut off chassis legs have you?

 

[potus]

Also made a jig for my tub fixings prior to cutting off the old crossmember tub lined up a treat afterwards.

 

[IamRobbie]

I'm confused, mate. You haven't welded the 4 corners of the new cross member legs together before sliding it on to the cut off chassis legs have you?

Thats what it sounds like

 

[Al2O3]

dwdw, if that's what you've done it's not a problem. You'll just need to run an angle grinder up the corners to cut them open again.
Have a look further up this thread at Southernlandy's pictures. They show exactly what to do. The picture of his new cross member with the 4 sides opened up is not just him checking it out. He would then have tapped the sides down on to the chassis, checked again that it was in the right place for the tub lugs using his jig and then welded the 8 side pieces (4 each leg) to the chassis rails.
Just keep asking questions if you get stuck. Loads of help on here

 

[dwdw]

As per the photos pushed new xmem on until the bottom touched old xmem then used G clamp to bring down each of the four extensions then welded them in place. What confused me was seeing photos of before & after but none showing if the old box section fitted inside the new. But when I offered the new section up I could see that both box sections were same sizes.

 

[Al2O3]

Sounds like you've sorted it, then.
Did you gauge the length right for the tub fixing lugs?

 

[dwdw]

Sounds like you've sorted it, then.
Did you gauge the length right for the tub fixing lugs?

Yes welding done & now painted just waxoil left to do. Yes fitted nicely after offering it up & grinding a bit off once or twice.