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I recently purchased a 99 GCL, Quaddrive, 4.7L with 54,000 mile on it. Like an idiot I traded a perfectly good 99 Cherokee sport that I had tricked out (headers, lg exhaust, 3" lift, throttlebody, etc) for the money pit :cry:. So far I have replaced the radiator $220, (I have that down pat now) and the dealer replaced the AC evap, one front hub/bearing, rear driveshaft/universal & transfer case (249), ($400 in deductibles under warranty). It was after they serviced the front/rear diffs ($240) that the noise first appeared. At around 70 there is a mild rumbling like an airplane taxiing. Then around 80-85 it sounds like a turboprop on takeoff. I have had this back twice for the same problem but the dealer is shining me on (that's normal for these vehicles) except that I have put over 3000 miles on it without a sound until they worked on it. This is one of the first built 99's with the original CV front prop shaft assy. I am wondering if the tech screwed something up in the front diff when he was servicing it. I also think it may be the front prop shaft that is getting ready to go. I am in the reserves stationed at Fort Carson, CO and i drive home to SLC about once every 60 days to visit fam. I just don't want this thing to fall apart on the way down/back. Any Ideas or does this sound all too familiar?
SFC Brown
 

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Did they put the additive in the front and read diff.? That helps keep that sound away
Why so much to service it? Read your papers, what was added/done to the diff. and post back :cool:
 

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Our 2000 Wj does the same thing, it's most likely due to the pinion angle for the rear driveshaft u-joint at the differential being set at about it's max angle ( I do have a 2 1/2" BB lift and UC springs though-not helping matters any there). It is annoying, but it does keep you from speeding for a long time doesn't it? :D I'm running Amsoil 75W140 Syn gear lube in the diff's, which is supposed to have friction modifier in it already.

If your front CV-style driveshaft was getting ready to go, it would most likely whine badly when coasting downhill, they seem to last OK as long as you don't put a lift on and disconnect your front swaybar, if you do you can kiss it goodby quickly!

I'm probably going to try changing the rear shafts u-joints soon. They are sealed joints, so they may be at the end of their useful life-54K here

John
 

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Bon&JohnsWJ said:
Our 2000 Wj does the same thing, it's most likely due to the pinion angle for the rear driveshaft u-joint at the differential being set at about it's max angle ( I do have a 2 1/2" BB lift and UC springs though-not helping matters any there). It is annoying, but it does keep you from speeding for a long time doesn't it? :D I'm running Amsoil 75W140 Syn gear lube in the diff's, which is supposed to have friction modifier in it already.

If your front CV-style driveshaft was getting ready to go, it would most likely whine badly when coasting downhill, they seem to last OK as long as you don't put a lift on and disconnect your front swaybar, if you do you can kiss it goodby quickly!

I'm probably going to try changing the rear shafts u-joints soon. They are sealed joints, so they may be at the end of their useful life-54K here

John
After reading your post, I checked AMSoil (Since I am a big fan and run it in my Atc's) and there is no modifier in there. I copied from their site: Synthetic alone is the reason you don't need to add "in most cases"

NOTE: AMSOIL Synthetic Gear Lubes do not require the use of this additive. However, not all differentials respond the same and if chatter is noticed, the addition of AMSOIL Slip-Lock will eliminate it. For chattering differentials not running AMSOIL Gear Lube, this product is an excellent solution to the problem.


I hope this helps :cool:
 

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njyahoo said:
I am wondering if the tech screwed something up in the front diff when he was servicing it.
What kind of "service" did they do to it? If they replaced the pinion seal, there's a very good chance that the shop monkey (like most typical dealer mechanics that are not trained to work on differentials) simply tightened the pinion back up with an impact without checking the pinion bearing preload at all. Not sure if a WJ D30 uses a crush sleeve or shims for setting the bearing preload, but more than likely it's a crush sleeve like the rest of the d30's, and he didn't replace the crush sleeve either.

The correct proceedure for changing the pinion seal requires more than just pulling off the yoke, slapping in a new seal, and putting the yoke back on good and tight. You can only do that on an axle that sets bearing preload with shims, as the shims can not crush and will only let the bearings get so tight, no matter how much torque you place on the pinion nut. On a crush sleeve one, you need to put a new crush sleeve over the pinion before replacing the seal, and then as you're tightening the pinion nut down to several hundred foot lbs in small increments, you need to constantly stop and check the torque it takes to rotate the pinion shaft/yoke with an INCH-pound torque wrench...most d30's need i think 8-12 INCH/lbs of bearing preload.

So if that's the service that was performed to your jeep, that could very well be your problem, and you're now in need of a full diff rebuild.
If they simply changed fluids in your diff, then that's probably not the problem and i just moved myself one step closer to carpal tunnel syndrome writing this! :thumbsup:

-Ron-
 

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njyahoo

thanks for the quick updates. As for the repairs/service here goes:
1) had whining noise from front when coming down off hills. Getting progressively worse. took into shop for that reason.
2) first time in shop - found front hub bearing worn/replaced with new. Found rear TC seal & vent bad. Replaced. Dealer advised that Diffs & TC needed 60,000 mile service. (assumed pulled covers, checked VL & added fresh oil & additive, It is a Jeep dealership). :(
3) Got veh back and first time on hwy is when the proproar showed up. Called dealer back next day.
4) Brought back to dealer: 2nd time - run out excessive on rear drive shaft. replaced with new shaft with spcl ring assy and new pinion Yoke.
5) TC shot, Replaced with new.
6) noise diminished but not gone completely.

So that is what has happened so far. I am just trying to pinpoint what caused the roar at highway speeds and how to fix it. I am to the point where I should save the $200 deduct and do the work myself. Sounds like the roar is from the Variloc Diffs.
Thanks folks
SFC Brown
 
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