ZJ rear end noise/movement

[dhreeves]

I have a buddy with a '96 ZJ full time 4x4. You have always been able to feel the front end pulling when turning sharp but recently the rear end has started making a noise and you can feel movement while turning sharp. The noise sounds almost like a tire rubbing but there are no visible signs of rubbing and it feels as though the whole rear end moves back and forth (left/right) a little bit. I looked and couldn't see anything visibly bent and it doesn't appear to be leaking anything. Any ideas?

TIA
Don

 

[Lawn Cher']

Check the rear track bar... it constrains the axle's lateral movement. Either the bushing or the ball joint could be worn out enough to let the axle shift.

 

[Eagle]

Does he have a Trac-Lok in the rear axle? If so, he should change the diff lube and be sure to add friction modifier.

 

[dhreeves]

It is the "up country" package but other than that completely stock. I looked under it again as best I could in my work clothes to check out the track bar but I couldn't even see one. Is it somewhere weird on the rea axle?

Don

 

[Eagle]

I believe Up Country includes Trac-Lok, which is a clutch-type limited slip differential. The clutch-type limited slips need a special additive to the gear lube to allow the clutches to release going around corners. It sounds like your friend may have changed the rear diff lube and not added the friction modifier additive. Comes in a small bottle (6 oz or 8 oz) that you dump into the rear diff.

 

[mmyers]

Check the rear track bar... it constrains the axle's lateral movement. Either the bushing or the ball joint could be worn out enough to let the axle shift.

Ball joint on the rear track bar......

I must not have gotten that option on mine

 

[Lawn Cher']

Well, I assumed the rear track-bar on a ZJ was similar to the front track-bar of an XJ, which has a bushing at the axle end and a ball joint at the frame end. I could be wrong, though. Please inform us of what is actually there...

 

[mmyers]

There is a bushing on each end, similar to the axle side end of the front.

Take a look at the axle side mount. They are notorious for cracking. If this is the case, you would feel what you are describing as the bracket is folding back and forth.

Not a good thing.

Look close at all of the control arms and mounts too.

M.

 

[Lawn Cher']

Thanks for the info, now I know more than i did before. This is naXJa, after all, not naGCa, so I was merely making an educated guess and can't be held responsible for SPOBI in that regard.

Makes sense that they would design it that way since there is no steering in the rear to require precise axle tracking that would necessitate use of a ball joint instead of a bushing.