hckrach

I have a 2000 Cherokee. I need to replace one of the outer front axle u joints, which I know is bad. Could that potentially cause play in the drive shaft leading to the front axle, along with bearing noise? I know I'll find out more when I'm done, as to which noises still exist. Also, if I still have bearing noise, how can I isolate which bearing is making the noise? I know of the turning left and right trick, where (correct me if I'm wrong), if the noise occurs when turning left, a bearing is bad on the right side, since more pressure will be on the right side. The reason I ask is in the summer of 2010, the rear differential was re-built (a pinion bearing had started to come apart). All 6 bearings were replaced, along with any seals and races. My brother-in-law helped me, and while neither of us had ever done a job like that, he had the toolds to measure backlash, and all that stuff. I would hope that diff isn't going bad in such a short period of time, although it wasn't done professionally. We never were able to verify which bearing was bad, until the differential was removed. In March of 2010, the left front hub bearing was replaced.

Essentially, only the right front hub bearing, along with the bearings in the front differential have never been replaced (I hear the bearing noise in 2WD and haven't tried 4WD).

A long story short, other than the s-turns, how can I tell which bearing is going bad? Even with the s-turns, how do I know if it is front or rear?

Thanks in advance

hckrach

bump

hckrach

sorry bumping again

hckrach

bump

Slick761

When you say play in the d.s. are you talking about twisting or up and down? Shake the pinion if there's play there its probably the pinion bearing.

hckrach

The play is twisting, not up/down or side to side

Slick761

Either u joints it preload on the pinion.

hckrach

I'm replacing the u joint tomorrow, so I will know a lot more then. Could that potentially cause a bearing noise, as well? Also, if I still have a bearing noise, my hope is that it is a hub bearing, and not one in the differential (much easier fix). Is there a good way to determine if it is in the front differential vs a hub bearing? My guess is it is not from the rear, since I rebuilt the rear differential in the summer of 2010, and all of the bearings, seals, and races were replaced (including the outer wheel bearings).

Slick761

Jack it up and shake the wheel top to bottom

DFlintstone

Generally a bad bearing will get hot. Eventually it will be REALLY easy to find, just follow the smoke!

But seriously....drive it for a good bit, then feel for heat. Don't know about the Diff. though. I would expect front differential bearings last a very long time.

hckrach

I replaced the bad u joint today. It was in very bad shape in all 4 caps there was play. I can't do much of a road test right now because it is raining fairly hard, so it is hard to determine whether the noise is coming from rain, or a bearing, but I still have bearing noise.

Since there was so much play in the u joint from it being in such bad shape, could that have caused either the differential or pinion bearings to go bad prematurely? The hub bearing on that side appeared to still be in good shape when I had it off for the u joint, it rotated without any noise or play. I will road test it tomorrow with s turns to load the other hub bearing to see if the noise gets worse. While a hub bearing is more expensive than a diff or pinion bearing, it is obviously a much easier replacement.

I will also change my differential fluid tomorrow. If a bearing is wearing inside one of the differentials, I should see signs of metal, right? If I don't see any metal shavings, that should mean it is not a bearing within the pumpkin, right?

DFlintstone

If your pulling the cover, drive it some first, then check for heat???

hckrach

OK, I'll do that. I really really hope it is the hub bearing on the other side than what I did today. The funny thing is, I'm getting ready to sell the car, and I just want to get it good enough to sell, but obviously bearing noise wouldn't be a good selling point.

The s turn trick, though, I found out with my rear diff, can be misleading. A friend and I did s turns on a road, and the sound was definately when one side was loaded, so we replaced the rear wheel bearing (both, since the hard part was just the prep for it). That didn't solve the problem, and a few days later I had a catestrphoic failure back there. One of the pinion bearings started falling apart. All the other bearings were in good shape.

The bearing noise seems constant, whether I am accelerating, or decelerating. I tried the s turns before, but the u joint made so much noise it was hard to isolate if the sound got better or worse with a turn.

Just based on experience, would you guess if the sound disappears and then gets worse with s turns it would be a hub bearing on the side with the noise when loaded in the s turns?

hckrach

OK, I checked for heat, and in the rear, all 6 seemed normal. The two outers felt like room temperature on the outside of the axle, and the 2 pinion and 2 differential bearings felt somewhat hot, but I had just been driving it. The all felt about the same temperature on the outside of the differential/axle. In the front, the same thing. I didn't end up pulling the cover off.

I jacked it up, and both front tires have no play, either top/bottom or side to side. I spun them both, and the sounds I heard just sounded like a tire spinning, like maybe a pad kind of touching the rotor, but no abnormal sounds.

I checked for abnormal u joints on the drive shafts at both ends, and everything appears to be good.

The only thing I noticed is the drive shaft leading to the front axle still has some play in it. It is a twisting play, not an up/down or side to side play. The play goes into the transfer case and the front differential. It is not a u joint. The twists maybe at the most about 1/32 of a turn, maybe less.

I road tested it with s turns. The slight "bearing" boise seemed the same with loads on both wheels. I am maybe wondering if it is tire noise, since I know they are similar sounds.

I guess I just need advice on what anyone thinks, especially on the twisting play in the front drive shaft?

Thanks

xjpioneer

Try pulling the diff cover and check the pattern with gear marking compound. This will give you a good indication of the differentials health.