My 99 XJ rear diff seems to have a good amount of play in it. The thing is, when it is cold it goes from park, reverse, to drive very normally, no clunking. When it is hot after driving it for a while, when I go from park to drive it will go into gear with a harsh clunk. Like there is a lot of play in the diff. Diff is full to the top, I checked it and it was just below the fill plug, I topped it off until it dribbled out. No vibration while driving, no noise. What i do to lessen the clunk is shift from park to neutral, then wait a second then shift to drive, and it is not as bad. Bad diff?

 

Re u the original owner? Could it have a lunchbox locking diff installed? They have a little more slack than the stock open diff.

 

I don't know about a Jeep axle but the 10 bolt axle the mechanic set up on my buddy's car had set too much backlash. It just plain blew up on on the freeway. Stripped off several teeth.... oh the sound Thing is it didn't give any warning. It wasn't loud, he goosed it and it let go...


To check to see if a locker is installed without taking the cover off... chock the front wheels, motor off, put trans in neutral, jack up one of the rear wheels so is off the ground and rotate it. If it turns with little effort then there isn't a locker in it. If it clanks/clunks then it may have a locker installed.

 

if it has a locker both tires will turn the same direction when jacked up off the ground. if it is open only one wheel will turn.

Also you could only lift one wheel off of the ground and if you have an open diff then that one wheel will turn with no issues, it will lock on you if you have a locker.

 

Its pretty obvious if a jeep has a locker. Tight turns in a parking lot with your foot on the gas or accelerating from a stop around a turn will result in your tires to chirp and you will notice it. When it rains it will be very easy to put sideways around a turn, very fun btw cause its very easy to control lol. Coasting around a tight turn you will hear the rear ratchet and when you apply some throttle you might get a loud bang. Ive notice understeer around turns with power to the rear as well.

It could be a worn out axle in need of replacement, pull the diff cover and have a look see

 

Haven't done a diff repair/replacement yet, practically everything else so I am sure I can handle it.

I am sure it is a non locker in there. My mother bought it a couple years back, it has been like that since she bought it. She brought it to a Jeep guy back then and he said it was fine, well...ummmm NO I think not. I traded my Ram 1500 for it because they wanted a truck and I wanted an XJ. So it worked for me. I am working the bugs out of it now. Would it be worth yanking the diff apart and putting a locker in instead? What should I look for when pulling the cover off?

 

Well if there is that much slop now, a locker will kill the axle. What kind of axle do you have? If yours have a flat flange on the bottom its a Chrysler corp 8.25, good axle. But pull the cover and see why is have so much. Might be better off buying a junkyard c8.25 from 97+ XJ's that isnt crap and lock that one

 

Yep mine is an 8.25. I'm gonna check it this weekend. Will let you know. Thanks.