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Old May 1st, 2012, 11:24 PM   #1
tmhd2
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Default D44a pinion bearings question

I'll start this off by saying I'm not an expert with axles by any means...

The patient is a 96 ZJ V8, which has the 'lovely' aluminum D44 rear end. Jeep has 180k miles on it, and somebody has obviously been into this axle before (more on that in a minute).

I bought this Jeep over the winter with a completely shot D30 front. The axle made so much noise that I totally missed the noises from the rear. I first noticed it as I got off the highway. As I slowed down, a cyclic 'grating / grumbling' noise was present. I noticed as I drove around town that the noise is most loud around 40ish MPH. My typical experience with axle noise is that bad pinion bearings will be impacted by acceleration / deceleration whereas wheel or carrier bearings will make a constant noise.

Armed with this belief, I put the Jeep on stands, ran it up to 40 MPH, and noticed the noise most prevalent around the driver's side wheel. I pulled the axles, did both wheel bearings for good measure (didn't get a chance to really judge their condition due to the slide hammer rendering them useless during the removal process), put it back together and noticed that it was just as loud as ever. Killer.

Pulled it apart again, pulled the axles, and pulled the carrier out. Nice, tight Timken branded bearing on the passenger side. Driver's side bearing has no markings on it, and slid right off the carrier (at least I only have to press one off now, right? lol). This bearing is also very worn and noisy when turned by hand.

Thinking this must positively be the culprit, I did a little victory dance and got to work with a bearing splitter and a hammer on the good side (might as well do them both, right?)

In the meantime, it seemed like the prudent thing to do to check the pinion bearings over thoroughly, as they are really all that is left in the diff at this point. I dropped the rear driveshaft, and lo and behold... The pinion turns nice and easy with no play or seal leaks or anything else out of the ordinary but it makes noise just like what i'm hearing when i drive. There are no rough spots or what I would consider an excessive amount of force to turn it...

The teeth on the ring and pinion show even wear, with no evidence of chipped teeth, etc.

Coming back to the first sentence in my post - I'm a bit out of my element, so here come the questions to the experts:

Is it normal to have some rotational noise in a D44a pinion? I'm guessing no, but hoping yes...

In the event that it is not normal, how serious of a problem is this? Keep in mind that there is no discernible play, leaking seal, typical accel / decel noise that accompanies failing pinion bearings. I would love to delay a total rebuild on this axle for at least a few months, but want to be realistic about the likeliness that this Jeep is going to SLSD this summer.

In the event that this is serious, would anybody in the Metro Detroit area be willing to charge a fair price to get it straightened out for me? I can either slap it back together and bring it to you, or you can come here and have the dis assembly already done for you. I can help or get the hell out of the way.

Thanks in advance

Tom
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