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  #1  
Old March 6th, 2018, 20:53
HH-Bham HH-Bham is offline
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1998 XJ-Time for Front Diff rebuild?

1998 4.0 XJ Classic, HP Dana 30 front, 165k miles, purchased 1 month ago. Been trying to track down grinding noise -- sounds almost like rubbing dust shield, but it isn't. Not awful loud. Can't hear with windows down or fan on high (or music playing), but noises bother me and it is there. Starts as soon as car moving and continues till 45 mph when wind and highway noises drown it out.

Noise isolated to front drivers side. All quiet on jack stands in RWD and in 4WD when drivers side wheel stationary and passenger side wheel turning. But when I block the p-side wheel so the front drivers side wheel turns, the noise is there.

Replaced driver's side unit bearing and axle u-joint but noise persists.

Differential oil was over 1" low and bunch of magnetic sludge on the screw. Haven't yet pulled the cover.

I'm guessing the only remaining culprit is the front differential. Specifically, maybe the diff bearing (side bearing?) on the drivers side since all quiet when D-Side stationary and P-Side turning.

Any suggestions besides pulling the axle and having the differential rebuilt?

Thanks for any advice.
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  #2  
Old March 6th, 2018, 22:32
freggie freggie is offline
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Re: 1998 XJ-Time for Front Diff rebuild?

I see you said unit bearing, is that the wheel bearing? I had a wheel bearing make a grinding noise which I assumed was the caliper sticking and it was metal on metal
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  #3  
Old March 7th, 2018, 04:19
HH-Bham HH-Bham is offline
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Re: 1998 XJ-Time for Front Diff rebuild?

Yes unit bearing meant wheel bearing.

Also should add that in my case I don't think it is the brakes. Applying the brakes makes no difference in the sound. Also caliper and pads replaced and noise still the same.
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  #4  
Old March 10th, 2018, 22:26
bridgerx bridgerx is offline
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Re: 1998 XJ-Time for Front Diff rebuild?

pulls the cover and have a look. If you pull the carrier just keep track of the shims and putting it back together is no big deal.
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  #5  
Old March 11th, 2018, 07:36
SByota SByota is offline
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Re: 1998 XJ-Time for Front Diff rebuild?

Quote:
Originally Posted by bridgerx View Post
pulls the cover and have a look. If you pull the carrier just keep track of the shims and putting it back together is no big deal.
The carrier bearings shim are captured by the pressed on bearings. No shims will fall out if you just pull the carrier.
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  #6  
Old March 11th, 2018, 15:27
HH-Bham HH-Bham is offline
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Re: 1998 XJ-Time for Front Diff rebuild?

Thanks guys. Yes need to pull the cover. Will report what I find. Gotta get my other vehicle running first. Thanks.
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  #7  
Old March 30th, 2018, 19:28
HH-Bham HH-Bham is offline
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Re: 1998 XJ-Time for Front Diff rebuild?

Finally got time to get into it. Good news I think.

With cover off, nothing looks broken, everything spins nicely when I turn either wheel, no additional sludge on magnet, no metal pieces in bottom of differential. Can't hear any noise. Tried to push the axle ends but no play in the bearings.

With carrier pulled (marked and noted which cap goes where) the drivers side carrier bearing is pretty loose. Slides quite a bit, about 1/4 inch, from side to side, and generally lose feeling. Only slight side to side movement in pass side bearing and much tighter.

I'm not going to attempt to try to pull the bearing or press replacement on -- watched videos. Don't have a press.

If a shop that works on differentials pulls off the bearings presses on new ones (with new races) and doesn't mess up the shims, can I just put it back in?
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  #8  
Old March 31st, 2018, 04:27
Jim Malcolm Jim Malcolm is offline
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Re: 1998 XJ-Time for Front Diff rebuild?

OEMs don't setup gears the same as the rest of us. They measure the housing and gears while they're being machined and calculate the shims required. Slap it together, a basic check and on to the next. When you swap Dana gears for Dana gears, you can compare the numbers on the gears and calculate how much you need to change the shims. They don't account for the bearing tolerance since it's much smaller than the gear setup tolerance. For discussion purposes, don't quote me on exact numbers, 0.0005" vs 0.0080". Your gears may be a little noisy if they've worn due to the bad bearing.
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  #9  
Old March 31st, 2018, 06:13
trippled trippled is online now
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Re: 1998 XJ-Time for Front Diff rebuild?

Quote:
Originally Posted by HH-Bham View Post
Finally got time to get into it. Good news I think.

With cover off, nothing looks broken, everything spins nicely when I turn either wheel, no additional sludge on magnet, no metal pieces in bottom of differential. Can't hear any noise. Tried to push the axle ends but no play in the bearings.

With carrier pulled (marked and noted which cap goes where) the drivers side carrier bearing is pretty loose. Slides quite a bit, about 1/4 inch, from side to side, and generally lose feeling. Only slight side to side movement in pass side bearing and much tighter.

I'm not going to attempt to try to pull the bearing or press replacement on -- watched videos. Don't have a press.

If a shop that works on differentials pulls off the bearings presses on new ones (with new races) and doesn't mess up the shims, can I just put it back in?
Yes you should be fine. Really any competent shop should be able to that for you.
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  #10  
Old April 13th, 2018, 21:31
HH-Bham HH-Bham is offline
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Re: 1998 XJ-Time for Front Diff rebuild?

Update: two weeks since I took the carrier out I got it on the road again. Had new bearings pressed on ($65 incl. bearings/races). Had a few days I couldn't work on it and replaced PS ball joints and u-joint, and a few other bits, and got a bit consumed with grinding and painting stuff while I was at it. Anyway:

All quiet on the western front.

Happy to have the XJ back in action and without drivetrain noise, that I can hear anyway.

To press in new seals, I used a 9-10 inch piece of 1/2 inch threaded rod, two nuts and a few washers along with a couple bearing and race installers. Just cranked on one nut on greased rod to press in place. FSM shows a turnbuckle tool but this was cheap and worked.

Thanks guys for pointing me in the right direction.
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