I have been dealing with this ever since I bought the vehicle last March. When I am at speeds between 40 and 65, the rear axle makes a constant, medium-pitch, droning. At first, I thought it was and exhaust leak. That was before I knew anything about Jeeps. The sound changes with the speed of the vehicle and not the speed of the engine. I have a limited slip diff and I am wondering if the lack of limited slip additive to the gear oil is what is causing this.

I am not as concerned about the noise as I am that it is symptomatic of a problem that needs to be addressed.


Any thoughts?

 

id say try a heavier weight gear oil like you mentioned. what LSD do you have? do you know that you need an additive? if your supposed to be running a specific gear oil and aren't, or you are supposed to have an additive in there and you don't - im guessing thats your problem right there.

 

What's your rear driveshaft setup like? It could be the angle causing the noise if it's not set properly. I seem to have the same noise/droning but i can feel it all over the jeep. I dunno what it is either. I have the same year xj too.

 

Are you sure its not uneven tire wear?

 

Or "cupping" of the tires??

 

it did it on 2 different sets of tires and also when it was stock height. The noise remained the same.

 

How's the pinion bearing? Any play in it?

 

How old is the gear fluid in the diff? You should pull the cover and take a look. I bet changing the fluid will solve the problem. Make sure you add friction modifier, unless your choice of fluid already contains it.

 

The Gear oil is only bout a month old. I didn't know that I had to add the LSD additive when I changed it. I added it this morning and i dn't think anything changed. As far a the inion bearing is concerned, how do I check for play? If there is play, what do I do?

 

If you didn't add the modifier when you changed the fluid, the cluth discs have probably been wearing against each other pretty badly. If the noise is being caused by the lsd, it's the cluthes grinding against each other that makes the noise. When they're grinding they are breaking down and contaminating the oil. Simply adding the additive now is a waste of time and money. The fluid should be changed. It's pretty cheap for the gear oil. IMO it's worth changing even if this isn't the cause of your headache!