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Rear Axle Clunk

Benzilla

NAXJA Forum User
Having a serious problem with the rear end in my Jeep. Before we get down to semantics here are the details of my Cherokee.

1999 4.0
225,000 miles
AX-15
8.25 rear end

So, the story of the problem. Starting about 6 months ago Every once and a while I would notice a loud clunk coming from the rear end when accelerating away from a stop sign or light and I would notice the same thing in reverse. It was a very powerful clunk that felt like someone rear ending me. Just in the last week it has gotten worse clunking more than once on acceleration and between gears, it now happens when I take a sharp turns. It is to the point where it is un-drivable. I don't think it has anything to do with transmission mounts or motor mounts because they are all new in the last 20k miles. It doesn't feel like axle wrap either. I am thinking its time for a new axle? Any input from experienced Jeepers?
 
pull the rear drive shaft and lube up the slip yoke splines.

If it's a stock tcase, the slip yoke is lubricated by the tcase oil, so how would lubricating it help? Normally if you pull it all the way out the oil will pour out.

Have you inspected your leaf springs, bushings, shackles, rear sway bar if you still have it, driveshaft ujoints, and well basically every external mechanical connection in your rear end for looseness or play? If not, grab a flashlight and get on that, and let us know what you find.

Your mounts may be new, but are the fasteners properly tightened?

Unless the axle has been really whooped on, why it would go bad so suddenly...
 
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pull the rear drive shaft and lube up the slip yoke splines.

1996-2001 have the external slip yoke.

Lubricating the slip yoke splines will cure the clunk that occurs when you stop/start that feels like somebody just hit your rear bumper.
 
Also check your u-joints.
 
Also check your u-joints.
Second that. Sometimes seized u-joints will not show any play for quite a while but they'll still misbehave. Also, check that your pinion yoke is not worn out. Eventually, the little tabs that position the ends of the u-joint caps can wear, and the end play will eat up joints fast. No amount of strap tightening will hold those caps tight enough. I've had a couple of them wear out in the 200-225k mile range.
 
Just to cover all bases...Do you also have a stock TracLok limit slip? If so, with your kind of mileage, it's probably grenaded itself by now.

Mine exhibited similar symptoms that you mention when it broke up, so I just thought I'd throw that out there...
 
Just to cover all bases...Do you also have a stock TracLok limit slip? If so, with your kind of mileage, it's probably grenaded itself by now.

Mine exhibited similar symptoms that you mention when it broke up, so I just thought I'd throw that out there...

No limited slip...


I have yet to tear it apart, I have another vehicle and the Jeep isn't my DD. I'll keep you all updated
 
I had the same basic problem on my old xj, before it got wrecked. I had the same thing goin on as well as clunking when i would shift from park to drive or drive to reverse. The consensus seemed to agree that my pinion gear was loose and had play. I had someone shift between gears when i was on the ground looking at it. The yoke and shaft spun about a half turn everytime.
 
So, I have done some detective work, I removed the rear driveshaft, no play in the u-joints and they are in pretty good shape. The splines on on the slip-yoke coming from the t-case are nice and lubed and there is little play when I try to rotate the driveshaft when only connected to the t case. The driveshaft came out with ease. There is slightly more play in the yoke for the rear end, I took a video linked below. It seems like a lot of slop to me so take a look.


On the other hand the leaf springs are getting a nice S-curve to them throwing the pinion angle off, could this be my problem? Or is the slack in the rear end indicative of something more serious...
 
I had this issue prior to the lift. My stock springs were very nicely S shaped and what I found was that the axle would wrap. In my case, I noticed it when I stopped. Come to a complete stop and then thunk goes the rear end. Got real brave and had my Son drive it while I watched. Could actually see the third member nose move after the Heep stopped and unloaded the spring. They do anyway but with shot springs it moved enough the be a problem.

New springs are the solution...
 
jack the rear end up, chock the front and jackstand the rear axle, put in neutral. drain and pull the cover, spin a tire to get to the carrier shaft pin, it should be a hex head on a 8.25... remove that, then the cross shaft, remove spiders and thrust washers, inspect for other damage...

hardest part is realigning the two new spiders... which isnt very hard, just takes a couple minutes to figure out.
 
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