Rear Differential question

A couple of people have told me that there is a certain type of limited slip additive that must be used with the gear lube (80W-90) in my 1997 Jeep Cherokee Sport 4wd (automatic) rear differential.

2 months ago I had the rear differential flushed & serviced. Not long after I had the flush/gear lube/additive change, I noticed a "binding" noise, almost a groan when I am turning the wheels to turn into parking spaces ...it doesn't seem to be making that noise at other times, only when making that tight turn, whichever direction I am turning.

Today I took the car back to the place I had the service done and they re-serviced the rear differential for me to see if that solves the noise problem. I'll know tonight when I get to work..because the noise doesn't happen until after I have been driving the car for some length of time.

So my question is: Is there a certain type of limited slip additive that must be used in the rear differential?

Also, could someone elaborate on the following quote I pulled from another post here on this same forum?

"Besides, flushing a high mileage AW4 thats shifting fine has mixed reviews anyway."


What kinds of problems might flushing produce, if any?

Yes, the mechanic said that there could be bearings going out...but I don't hear the noise while driving....only when turning at slow speed and making a tight turn. Could it be an early sign of bearing wear?

Thanks in advance!

Kit

If you have the limited slip axle in your jeep, then you will need to add some additive to the differential. If you do not have the limited slip, then you can do without the additive. I would drain some fluid out and add some LUCAS to see if that makes a difference. The reference to flushing the AW4 if talking about the automatic transmission and not the diff.

A couple of people have told me that there is a certain type of limited slip additive that must be used with the gear lube (80W-90) in my 1997 Jeep Cherokee Sport 4wd (automatic) rear differential.

2 months ago I had the rear differential flushed & serviced. Not long after I had the flush/gear lube/additive change, I noticed a "binding" noise, almost a groan when I am turning the wheels to turn into parking spaces ...it doesn't seem to be making that noise at other times, only when making that tight turn, whichever direction I am turning.

Today I took the car back to the place I had the service done and they re-serviced the rear differential for me to see if that solves the noise problem. I'll know tonight when I get to work..because the noise doesn't happen until after I have been driving the car for some length of time.

So my question is: Is there a certain type of limited slip additive that must be used in the rear differential?

Also, could someone elaborate on the following quote I pulled from another post here on this same forum?

"Besides, flushing a high mileage AW4 thats shifting fine has mixed reviews anyway."


What kinds of problems might flushing produce, if any?

Yes, the mechanic said that there could be bearings going out...but I don't hear the noise while driving....only when turning at slow speed and making a tight turn. Could it be an early sign of bearing wear?

Thanks in advance!

Kit

Wow 1 Youve got like three different things going on here.
You are concerned about a noise when you turn sharp.
As was mentioned, the AW4 question is about the automatic transmission. That has nothing to do with the noise you describe.
The rear diff fluid was changed. That probably has nothing to do with the noise you describe.
Your noise is most likely related to something in the front end such as front axle u-joints or possibly steering related.

Yes you do need an additive if you have a rear limited slip and want it to work. The additive is called friction modifier and it is added to allow the limited slip clutches to grab. Without it, the clutches just slip and the limited slip doesnt work. I cant see how that would cause a "groan" while turning. I think your "groan" is unrelated to your rearend.

Hmmm...after they re-serviced the rear differential 2 days ago, the noise has disappeared. It's my suspicion that they never put the limited slip additive in the first time I had the service done.

Thank you for your replies.

WOOHOO! Thanks for posting this thread.

I was having this exact same problem recently with my 1998 XJ (US Forest Service surplus) where it would "chatter" in the back end whenever I would take a tight slow turn, like a u-turn. I found your thread on this subject, and also stumbled onto one at jeep forums (http://www.jeepforum.com/forum/showthread.php?t=601770) on how to tell if you have a LSD (limited slip diffy)

This other website (http://www.performanceoiltechnology.com/differential_clutch_chatter.htm) confirmed that this kind of chatter could be from a limited slip differential that didn't have friction modifier in the diff gear lube.

I had in fact just drained and replaced the gear lube in my diffy a few months ago, but didn't put any friction modifier in it, because I just assumed it was an open carrier.

Well thanks to the Jeep Forums thread I found out how to check for LSD, and was pleasantly surprised when I jacked up the vehicle in neutral and found that both rear wheels spin the same direction when you spin one of them. I guess this means I have LSD and that makes me pretty happy. Especially since I was considering buying an Ox Locker for my rig, but now I won't have to. LSD is good enough for the of (ab)use I put my Jeep through.

Since my Jeep is a gubmint surplus SE model, I figured it wouldn't have anything "nice" like limited slip. I guess the USFS figured the limited slip would be important for the kind of work they do with their vehicles, so they must have ordered up a crap load of XJ's with certain features not found on most SE's -- at least that's my guess.

So now I just gotta go get some friction modifier and put it in the diffy and the noise should go away I HOPE.

Thanks again for the info!

I had the same noise in my jeep but it went away after i replaced shocks ,sway bars, u joints and played with my alignment. so i am going to have to second the front end issues, not saying any of that is the issue but i would at least take a look and shake/tighten some things up, it wouldn't hurt