I need some expert help. The gf has a roar coming from the rear end on her 99 WJ - I'd like help her out and see if it's as bad as she has been told. "Shop" says that she needs a completely new rear (hers look amazing to me :laugh: haha...) but I don't think so. It's a Dana44 with 3.73 the limited slip. At speed there is a roar, very noticeable that increases in volume as you get faster. Sounds just like very aggressive tires, but she just has mild Bridgestones. I pulled the cover to change the oil with 80-140 LS additive, and there was some metal on the magnet, and some in the oil. I dont' do gears much, so i don't know what is a "normal" amount of metal. The ring teeth are smooth and sharp, not worn over, and there are no chipped teeth on it or the spider gears that I can see. It had been leaking she says, but I dont' believe it was really low. I was thinking she needs new clutch packs in the carrier, until i noticed the passenger rear wheel has goo in it from a fluid leak. Couldn't check that as she had to leave for work. Would a wheel bearing make this noise? leaking seals cause other issues? Thanks for the insight.
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Roar from rear diff
- Thread starter CarbonXJ
- Start date
- Location
- Rainy side of Washington
A roar from her rear end? Stop going to Taco Bell...
Does the roar change at all with throttle modulation? If it does, there's a higher chance it's inside the diff, but if it doesn't, it's probably a wheel bearing. You can also check which wheel (unless both wheel bearings are going bad of course) by taking some corners fast, whichever corner is louder when it's on the outside of the corner is the one with the bad bearing.
Also, check the pinion bearings by grabbing teh pinion yoke (with the jeep in neutral and the transfer case in neutral) and trying to shake it side to side. If there is any play side to side, those bearings are definitely junk. The carrier bearings you'd have to open the diff again to check, so I'd check those last.
Does the roar change at all with throttle modulation? If it does, there's a higher chance it's inside the diff, but if it doesn't, it's probably a wheel bearing. You can also check which wheel (unless both wheel bearings are going bad of course) by taking some corners fast, whichever corner is louder when it's on the outside of the corner is the one with the bad bearing.
Also, check the pinion bearings by grabbing teh pinion yoke (with the jeep in neutral and the transfer case in neutral) and trying to shake it side to side. If there is any play side to side, those bearings are definitely junk. The carrier bearings you'd have to open the diff again to check, so I'd check those last.
MAY POP
NAXJA Forum User
- Location
- Lake in the Hills Il.
It will probably be a carrier or pinion bearing that has worn out. This can not be seen with out taking it apart.
8Mud
NAXJA Forum User
- Location
- Central Germany
What I do is block the tires, put it in neutral and make sure the drive shaft is loose (twists a little). Slap the side of the pinion and see if there is any sideway movement, sometimes you can hear the click before you feel the movement.
I pry up on the ring gear, The weight of the carrier tends to take up the play on the carrier bearings, so if you pry it up on the carrier you can see/feel the movement. If it gets louder in reverse it is likely to be the carrier.
Wheel bearings are a little harder to diagnose. First make sure it is actually seeping gear oil and not brake fluid from a leaky wheel brake cylinder. The quickest way I tell is by the smell. In and out play on the rear axle shaft usually doesn't mean much. Sideways or up and down play does, but here is the catch, the wheel bearings aren't real tight when new. Judging if they are acceptably loose or exceptionally loose is sometimes a guess at best. When they are loose enough to wear out the axle seals, is usually when I change them. You can sometimes put it in neutral, put it up on jack stands and slowly turn the axle with the drums off and feel a rumble from the wheel bearings. But sound travels in the drivetrain and it can fool you, you may be feeling anther set of bearings or U-joints rumble.
How loud is it? I've driven tens of thousands of miles on bearings making some noise. My XJ has so many rattles, squeaks, creeks and groans one more low pitch noise is hardly noticeable.
You stating you found metal flakes on the magnet and in bottom of the case suggests to me you have carrier bearing issues. There is a low spot under the inside of the pinion, cast into the case, metal from the carrier bearings tends to collect there.
I finally changed the carrier bearings out on my YJ when the neighbors started to complain.
atriot:
I pry up on the ring gear, The weight of the carrier tends to take up the play on the carrier bearings, so if you pry it up on the carrier you can see/feel the movement. If it gets louder in reverse it is likely to be the carrier.
Wheel bearings are a little harder to diagnose. First make sure it is actually seeping gear oil and not brake fluid from a leaky wheel brake cylinder. The quickest way I tell is by the smell. In and out play on the rear axle shaft usually doesn't mean much. Sideways or up and down play does, but here is the catch, the wheel bearings aren't real tight when new. Judging if they are acceptably loose or exceptionally loose is sometimes a guess at best. When they are loose enough to wear out the axle seals, is usually when I change them. You can sometimes put it in neutral, put it up on jack stands and slowly turn the axle with the drums off and feel a rumble from the wheel bearings. But sound travels in the drivetrain and it can fool you, you may be feeling anther set of bearings or U-joints rumble.
How loud is it? I've driven tens of thousands of miles on bearings making some noise. My XJ has so many rattles, squeaks, creeks and groans one more low pitch noise is hardly noticeable.
You stating you found metal flakes on the magnet and in bottom of the case suggests to me you have carrier bearing issues. There is a low spot under the inside of the pinion, cast into the case, metal from the carrier bearings tends to collect there.
I finally changed the carrier bearings out on my YJ when the neighbors started to complain.
atriot:
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Digger87xj
NAXJA Forum User
- Location
- Buffalo Creek/Lakewood CO
Very common on the WJs. I've done 20 or 30... Re-bearing it and you will be good to go.
I laughed way too hard on that...
It's been crazy at work and I haven't had a chance to get the WJ back, but I will look into the wheel bearings. The roar does not change with throttle, it's dependent on speed only. I'll do the tests suggested for the pinion and wheel bearings, and report results. I do not want to open that case up again, as it's just a PITA to work on at stock height (she won't lift, has to seriously jump into my XJ).
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