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Unread 06-30-2013, 07:39 AM   #1
cnaccarato
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ZJ Rear Differential Noise...

Hi everyone,

I'm new to the forum and a new Jeep owner as well. I just bought a 1997 Grand Cherokee and I took it in for an inspection and two different places told me that I need to replace the rear differential because the noise that its making. They said it's probably a pinion bearing gone bad and to replace all bearings. Does anyone know how to do this? I have no experience working on cars but I don't want to spend a whole lot of money to get this done. Any ideas or insight? Or if anyone in the Seattle area wants to help me go about doing this that would be awesome too!

Thanks for your help!

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Unread 06-30-2013, 09:53 AM   #2
JS97ZJ
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In order to do a rebuild on the diff, you need a couple of specialized tools and a dial type torque wrench.
If you don't get it right you could end up with more than just noise in a very short time.
Here is a link to Morris 4x4. They have a knowlede base online factory repair manual that you can look up the proceedure for doing the job.

https://www.jeep4x4center.com/knowle...ex.htm#service

Many guys will just get a replacement at a u-pullit. You could also check youtube for videos on the topic.

Welcome to the forum.
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Unread 06-30-2013, 10:03 AM   #3
ZeeJay1997
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Did it fail the inspection because it is making a noise?

If so, that is bull....

I can see leaking... but making a noise...?? !!!
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Unread 06-30-2013, 12:17 PM   #4
StPaul59
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Quote:
Originally Posted by ZeeJay1997 View Post
Did it fail the inspection because it is making a noise?

If so, that is bull....

I can see leaking... but making a noise...?? !!!


I think he means he just took it to 2 different mechanics.
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Unread 06-30-2013, 12:22 PM   #5
ZeeJay1997
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Quote:
Originally Posted by StPaul59 View Post
I think he means he just took it to 2 different mechanics.
Oh, Thanks. I guess you can tell i have an aversion to vehicle inspections.
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Unread 06-30-2013, 02:45 PM   #6
Oldfrog
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Register it in Georgia, they dont even have inspection stickers.. ( at least they didnt when I was dating a lady in Augusta, a few years ago.)

Seriously though....if it makes the noise only when you accelerate or put a load on it, it's probably just a pinion bearing.
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Unread 06-30-2013, 05:21 PM   #7
Jenglish
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How bad is it? Mine makes a very slight whine and the stealership wanted to replace it... for $1 billion
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Unread 06-30-2013, 08:20 PM   #8
cnaccarato
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The noise is pretty noticable...I just want to get it taken care of so that I can take the jeep on road trips without worrying about it breaking down. As you can tell, I don't know too much about cars but both mechanics who looked at it said it's something that needs to be done. And one of the mechanics is a family friend so I trust his word because he isn't in it for the money.

I'm just wondering if my best option is to swap out the whole rear axle or just rplace the bearings in the diff? Does anyone know which route is cheaper and a better fix? I think I have the C.8.25 rear end instead of the Dana 35. Does that make a difference at all?
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Unread 06-30-2013, 08:26 PM   #9
Oldfrog
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Get your mechanic friend to jack it up, pop the differential cover and take a look. If he knows his stuff, he'll be able to hear it as he turns the wheels. It might just be a wheel bearing.
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Unread 06-30-2013, 09:14 PM   #10
Uniblurb
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This is what Chrysler has to say about gear and bearing noise. When my left wheel bearing was going out it made kind of low growl but the bearing wasn't real bad and couldn't hear it but at low speeds. I'm pretty sure my pinion bearing is going bad and it makes a constant high-pitch whine at freeway speeds.

Wow, haven't seen the image insert feature working correctly for a while!
gear-bearing-noise.-p.3-3.jpg  
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Unread 06-30-2013, 09:16 PM   #11
um7267
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jack up the back end on jack stands, block front tires have a buddy start it and listen if it is coming from the "pumpkin" its most likely pinion bearing, and your almost better off going to a junk yard and getting one. if it is coming from left or right its a wheel bearing and thats just a pain in the ars to replace.

i did this with mine when i thought the pinion was bad, and after listening it made no noise, my guess is i have a bad u-joint somewhere on the drive shaft
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Unread 07-01-2013, 12:04 AM   #12
cnaccarato
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Yeah the mechanic jacked it up and took his stethescope and listened to the wheels and the diff and he said the noise was definitely coming from the bearings inside the diff (most likely the front pinion). So that's why he said it needs to be fixed soon but I just don't know if I should buy a set of bearings or just try to swap out the axle.

And does anyone know about the gear ratios being different between the C8.25 and the Dana 35???
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Unread 07-01-2013, 02:26 AM   #13
Uniblurb
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If it's a Dana 35 it will be cast on the back of the housing just to the top/left of the housing cover. Also it will have a metal tag attached to the cove by 2 bolts with the first 3 digits on the bottom/left of the tag as the gear ratio. That is if someone didn't swap the axle already or remove the cover tag.

Not sure where markings would be on a C8.25 and maybe on the top of the passenger side axle facing somewhat towards the back.

You should fill out the last 8 digits of your VIN along with your mileage in the below link and get a build sheet for your ZJ from Jeep/Chrysler. That way you'll know exactly what came w/it from the factory including options. Just type "Request for build sheet" in the box asking the reason for contact. Wouldn't hurt to also ask for any recalls/known recall work done. Fairly quick response and you should receive a reply w/your build sheet emailed to you in 2-3 days.

http://www.jeep.com/wccsapp/universa...ull&category=U
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-Stalling ZJ? 12 things to check before replacing a sensor; the Dirty Dozen
-Crankshaft position sensor multimeter test. & video of testing.
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Unread 07-01-2013, 09:11 AM   #14
cnaccarato
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Thanks a lot I just filled that out and submitted it! Hopefully they get back to me soon. I appreciate all the help!
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Unread 07-01-2013, 10:30 AM   #15
Uniblurb
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YW and what type of noise is it making in reading the diagnosis I posted? Does your 97 seem like it was well maintained with clean fluids at proper levels? Maybe the owner sold it because of the differential noise?

Not sure if it's true but I read on the 96-97 D35c ZJ's they installed some faulty carrier bearings. With the high-pitch whine on mine I'll probably tackle replacing the pinion bearing/seal with new collapsible spacer (crush sleeve), carrier bearings, and try to get some loaner specialty tools at the auto part stores. No sense is swapping out the whole axle since I have new outer wheel bearings/seals, fairly new brakes/calipers, working parking brake w/new cam/lever, etc.. Know all those brake parts are easy to switch over though.

Something I find odd is I've always run Valvoline 80W90 in my 96 35c even though I have the tow package w/3.73 gearing. Since I hardly tow anything this worked fine but developed a slight pinion seal leak at the front of the yoke last year. So I changed out the fluid to Royal Purple 75W-140 with friction modifier. While the spec is for this synthetic weight gear oil if you have the tow package also read you shouldn't use friction modifier gear oil unless you have the LSD (limited slip differential). Odd that the pinion seal leak stopped but the pinion bearing started making a high-pitch whine right after installing Royal Purple. Maybe just a coincidence and the pinion bearing was starting to go out anyhow? Whine isn't real bad, only hear it at freeway speeds, and maybe I'll try Shaeffer's #267 80W90 which is supposed to be good/quiet noise. But know no different types of gear oil is a cure if you have worn/bad parts.
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-Stalling ZJ? 12 things to check before replacing a sensor; the Dirty Dozen
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