Diff jig out of old chassis

[JMortensen]

I've got a 75 that is stripped down and ready to go to the JY. Was thinking of cutting out the rear suspension mount points so that I could mess around with installing different differentials, suspension mounts, etc. Problem is that I'm worried about the whole thing twisting if it is cut out of the rest of the unibody. Maybe a solution might be to weld in a strut tower bar, a bar across the rear frame rails, and one across the front diff mount area, and then triangulate, and THEN cut away from the rest of the chassis. I think if I could cut this thing down to size it might only be 80 or 100 lbs and maybe 4' by 3' or something like that. It's either that, or wait until I'm ready to do something and then buy another chassis. What do you think? Crazy idea?

[JMortensen]

Looked again and it seems like there are 2 ways to do this. Cut out the floor and the torque box and not the strut towers, or to take the strut towers also.

[cockerstar]

I'd take as much as you need to be able to mount an entire suspension. It might even be a good idea to try and take the wheel wells too, so you can get a full mock up on any new rear end you might want to mount.

It's easy to cut off anything that ends up being excess once it's all out, but it's harder to add metal back on!

 

Weld in some cross braces before you start cutting and I would think you'd be able to keep it straight.

 

I see:

- one as a strut tower brace

- one between the outer edges of the wheel arches

- one across the frame rails

Edited July 24, 2012 by cockerstar

[johnc]

You'll need the wheel wells, strut towers, rear bulkhead, some of the tunnel, and most of the subframe. Weld an X between the strut towers, a bar across the top of the tunnel welded to the tunnel and the front of the wheel wells. These bars can be square tube 1 1/2" .063" wall. Mount the whole thing upside down on HF engine stand.

 

EDIT: I'm agreeing with cockerstar.

[JMortensen]

I see your points guys. I think I may end up just trying to get everything from the mustache bar to the front diff crossmember, as that is really the only part that concerns me now, and it is all very close to the torque box structure and the mustache bar is right on the biggest frame rail in the rear. I'm thinking if I don't cut out the wheel wells and leave the torque box whole that this section may be strong enough on its own to be separated from the rest of the chassis. I don't have room for the whole back half of the car, which is basically sounding like the other option..