02BlueWJ

Hi folks, I'm new here, though I've been lurking for about a month now. I recently bought an '02 Jeep Grand Cherokee 4.0 2WD. It has been making some noises in the rear end since I bought it. When making turns at low speed, I get a bad groaning from what sounds like the diff. I had my wife make slow turns while I walked along side and noticed the inside tire on the turn (left tire when turning left, right tire when turning right), will stutter. The noise is loud and is accompanied by physical vibration. The other noise is a whirring noise while driving. The noise is most noticeable around 20-30 mph, but it's constant while in motion at any speed. It sounds almost like big off-road tires, but the WJ has street tires on it.

Here's what I've tried based on some online research:

I inspected and replaced the rear rotors and pads. I checked the e-brake shoes and that all seemed fine, though it was out of adjustment. I also replaced the diff lube, in case it had the wrong stuff in there. I went with Royal Purple 75W-140 full synthetic with LSD additive in it. Neither helped the issue at all. I didn't find too much in the diff housing other than some fine shavings and what seemed like a tiny piece of a spring (<1/16" x 3/8").

So, I'd like to know what could possibly be wrong with it? I'm thinking bearings, but I'm not sure if it's the wheel/axle bearings, the diff bearings, or the pinion bearing, or a combination. Any help would be greatly appreciated.

Schindler

Locker? Limited Slip going bad?

02BlueWJ

It's not a locker. It's a stock diff, which from my research, I believe is a Dana 35. The diff housing didn't have a tag on it specifying which diff it is, but from what I've read, an '02 WJ with the 4.0 and 2WD should have a Dana 35 in it.

I was wondering if it could possibly be the diff, but I figured if the clutches in the diff were going bad, it would slip rather than lock up (making the tire stutter on turns). I don't trust shops in general, so I want to try to narrow this down and do it myself, if possible. Though, I know if I want to replace bearings, I'll need a shop to press them on/off for me.

jnicewan

A limited slip can grab/chatter worse when they start wearing out. I have seen it before a few times. They will usually chatter a lot worse and can even make the rear shake and pop a bit.

Since you included a noise around 30mph, I would put the jeep up on a lift if available or put the rear end up on jack stands and run it up to the speeds that might duplicate the noise, then crawl under there and see if you can tell where the noise is loudest (be carefull of course).

It really sounds like you need to dis-assemble and inspect bearings though. Its hard to say which or what bearings, but you will need to remove the axles to get the carrier/diff out, so the wheel bearings will get checked first, then you will remove the diff/carrier and inspect those bearings, and while the diff is out you can inspect the limited slip clutches. Last thing left is the pinion bearings. Of course you will want to inspect all the ring & pinion teeth for a good pattern and abormal wear

dave1123

First of all, if you've got clutches in your diff, you've got limited slip. There is a spring package to proload the clutches. It's mounted in the center of the diff on the planetary cross shaft. If one of the springs is bad, it could cause your stutter. Seeing as how you found a piece of spring in the diff, I would recommend cleaning out the diff, inspecting the clutch packs, and replacing the springs. I've never done a jeep, but I have had LOTS of experience with GM Posi-traction. I believe GM used Dana gearsets so it should be similar. Here's what I did on my drag racer;

1- Drain & clean out the diff.
2- Pull out the planetary shaft. there is a bolt securing it. Be sure not to disturb the shims behind the planet gears. they are curved washers and should stay in place.
3- Pull out the center steel box with the springs in it. There should be 4 coil springs between the 2 halfs.
4- The clutch packs are behind the axle gears so if you want to replace them, the axles need to come out. You probably don't need to change them yet, so skip this step.
5- Replace the springs with new ones, reassemble, lube, and drive it.

On my Camero, I broke the planetary shaft twice and still used the same clutches so I wouldn't worry about yours.

I would still like to see you buy a 4-wheeler though!

I had a whine in mine the other day, but I stopped and made her get out!

02BlueWJ

I've never had a diff go out, so I didn't know what symptoms it would show. Thanks. I should be able to hear the noise from under the car without spinning up the tires too much. The whirring is present as soon as the car starts moving, it's just the loudest around 20-30 mph. Looks like I'll be doing a full tear down. Good thing I have tomorrow off.

Thanks for the info. Are the springs in that spring package really small? The little piece I found in there was tiny @ less than 1/16" thick by ~3/8" long and it was a tension spring rather than a compression spring.

I'd love to get into 4-wheeling, but just don't have the dough right now. The WJ is more of a grocery getter. I have a drag car myself that I'll probably be selling pretty soon. It's a '93 Mustang Coupe with a stock 5.0 motor and twin turbos. It's got full drag suspension, but it's sort of a sleeper because it's full stock interior/exterior with the exception of the Centerline Telstars it's running on.

dave1123

One thing I have learned in my years that I'd like to pass on;

DON'T BEAT ON YOUR DAILY DRIVER!! It may not get you to work the next day!

02BlueWJ

It's been forever and I completely forgot to update this thread. In trying to fix the binding issue, I discovered my WJ was optioned strangely in that it has a 4.0L with 2WD, and came with a Dana 44 rear end, rather than the more conventional Dana 35. I also discovered that my problem was the poor service of the previous owner (or whoever worked on it). They did not put friction modifier in the diff when they serviced it. And, apparently, the LSD additive in the Royal Purple gear lube is insufficient. So, I pulled the rubber plug on the diff, sucked out a little oil and replaced it with a bottle of Ford friction modifier. It worked like a charm. No binding in the diff, even in the tightest of turns.

I hope someone finds this fix helpful.

Basslicks

I'll let you know if I find it helpful. I have a 2000 WJ with 4.7L and 2wd and I was very surprised when I saw that there was a D44a in the rear. I haven't had the binding and stuttering in the rearend, but I've been having the whirring noise. Mine starts out low, but the volume increases and tops out at about 40 MPH and just remains constant from there on. I too was thinking it was the bearings.

I'm going to hazard a guess that the D44a's come with LSD? If so (or even if not), should I service my diff with the lube you stated?

02BlueWJ

The binding and shudder I had was caused by a lack of friction modifier. I still have the whirring noise, but it's not bad enough to be annoying and it hasn't gotten worse, so I haven't bothered checking what bearings are causing it.

I believe there should be a tag on your diff that will identify it properly. If not, a dealership or some Jeep parts places can do a search by your VIN to identify the diff. If it's the same as mine, you can use any 75W-140 gear oil, but you should put in a bottle of friction modifier (I think I paid $8 at a local Ford dealer), rather than relying on the LSD additive that may be in the gear oil.

Basslicks

Thanks