1999 XJ. 4.0, 231, Dana 30 front, 8.25 rear. 268K miles. Owned for several years now. On longer drives it starts getting a "Wowowowowowowo" in the front end somewhere. Sounds like a bad hub-bearing but I have replaced them TWICE now with both precision and Timken. No changes. It DOES go away if I remove the front driveshaft. Today, I decided to replace the carrier bearings for funzies. The original ones were PERFECT and didnt need messing with. So now I have that to finish up..

This is a also my 3rd front driveshaft. I played musical shafts with my other XJs over the years with no change in the sound.

The droning only starts once I drive for about 10 miles or so. 10MPH to 80MPH. Never really changes pitch either. Just a loud annoying drone.

The XJ was bone stock until last year when I tossed in a 3 inch lift. Longarms etc. Drone still there.

I ruled out the pinion bearing as it doesnt increase pitch with speed and its a low grumble/howl. Just gets louder with speed.

I seems to be the same as wheel speed.

Ideas?

Ugh.

Bonus Pics. Both races were smooth. Although it appears to be "chatter" on the diff snout.. Odd..


The rollers. Picked up some dirt on the bench.


Nitey Night. Diff spends a night in the deep-freezer next to the corn.


The new bearings waiting to be warmed and shoved onto the diff tomorrow AM..

 

What gear oil are you running. Sounds like its warming and thinning. All my diffs have had almost 300k on them over the years. Never took them apart like you. One year I drained and filled with Royal Purple....made so much noise I had to take it out the next day. I run name brand 140W and mix 50/50 with lucas. They run much quieter than before. Might also be a t/c bearing issue. Might be difficult to tell between the 2 positions as far as noise., but you are obviously way more advanced in diff particulars then me. You must have some wife to let you toss a diff in the freezer.

 

Wife hasn't found out about the freezer usage yet.. I run 75/90 syn in the front. I have half a bottle of 75/140 that I will use up today with the 75/90 and see if it changes..

It may be TCase related tho. Ill button it back up in a bit and go for a drive. If it starts humming again I will pull the front DS and go from there...

Snow in the forecast and I really don't want to drive around in 2WD.. I have the car for that.


New bearings installed. Overnight in the freezer and 30 mins at 400F for the bearings. No problem.

 

Update: New bearings installed, swapped both front hub bearing around, rotated tires, removed front driveshaft. No change. Still sounds like I'm driving over a steel grate from 35 to 45MPH from the front end. Drove on a dirt road in 4HI and no change before pulling the front driveshaft. I guess its just the way it will be. Ill install a new CD/bluetooth player and some new speakers I guess.

 

Check the output and the chain in the transfer case.

 

Yeah.. Im thinking next summer will be t-case refresh time. Its starting to leak in places. I should be able to make it one more winter.

 

Are you running MT (Mud Terrain) tires on your Cherokee? With the lift did you go up to 31" or 33"? What size tires?
If you went larger and used MT, that's probably what your noise is right there. What I bought my Chevy 2500HD Duramax it had a 6" lift on it with MT 35" x 12.5" tires. It was LOUD! I couldn't hear the diesel engine over the tires, I no longer run MT because I don't need that type of tread on my truck, AT work just fine or the new Coopper AT2 work great.
Also your power steering pump will groan as it becomes low on fluid, have you checked it?

Good luck, I have a similar problem with my Chevy, a clunk-clunk whenever I pull into my driveway and tweak the front end, or go over a rock or ditch or rut... like I have a bushing that needs replacement or a bearing that is out but I've replaced all that stuff like you. I've come to live with it, one day I'll be out shopping at Lowe's and I'll lose a shock or something random. lol

 

I 100% support your solution of upgrading your stereo. It’s the ultimate fix!

 

I would really check that transfer case out. Pop the front driveshaft off and see how much the front yoke can rotate in 4H. The amount of rotation tells you how worn out that chain is. I'd say if you can rotate it more than about a 1/8th of a turn, replace the chain. Even a full rebuild kit with bearings and a chain is like $120 last time I rebuilt one about a year ago.