What is a uni-body chasis?

[Doug B.]

I have as my daily driver a '96 Cherokee, and it is of a uni-body construction. I know it makes it a lot lighter, but what did it sacrafice? Just curious about the difference between the new and the old.

[joe]

Doug, it's not a unibody. The XJ is a uniframe. A lot of cars now are unibodies where there is no frame under the full length of the car as in your FSJ, just stub frames welded at each end to support the axles, motor. The XJ does have a full frame under it but it's a much lighter gauge frame than a regular car and where a conventional framed car has the body bolted to it, the XJ's is welded to to the frame.

[The Anti-Chrysler]

And in most cases nowhere as stiff as a separate frame. I have seen several occasions of people towing a heavy trailer with a XJ, (within it's towing ratings keep in mind) only to have the back doors become un-openable afterwards. Yep, body tweaking.

I'll stick to full frames, thanks. One of the reasons I went with a S-10 Blazer over an XJ for a daily driver.

[Lister]

Big difference is no option to add a body lift to get tire clearance.

The doors and rear hatch are part of the structural integrity of the vehicle, so if you are flexed out and open your rear hatch, you can't close it again until you are on flat ground.

[The Anti-Chrysler]

The doors and rear hatch are part of the structural integrity of the vehicle, so if you are flexed out and open your rear hatch, you can't close it again until you are on flat ground. Hence why the rear doors on the one I saw couldn't be open - the body flexed tight against them until they gave the body the added rigidity.

I believe a unibody has no place on a potent towing vehicle, such as the XJ and Grand that have stout motors capable well beyond their platform. :rolleyes: