99 Jeep Classic - Front End Rumble

In a previous post I asked about tires. At issue was what I suspected was cupped tires and the sort of rumbling noise they make. Winter is over, I expect to be driving mostly highway and I replaced the tires with a highway all weather radial. It didn't fix the problem.

The noise is sort of a rumble and I think from the front end. Sometimes it's more noticeable than other times but it just sort of fades in and out. It's a 4WD Manual and pushing in the clutch doesn't seem to change things much. It's more noticeable at highway speeds but can be felt as low as maybe 20MPH. I jacked up the front and can feel nothing abnormal. The Jeep has 153,000 miles.

I figured the choices are: Wheel Bearing(s), CV/U-Joint, Differential or defective tires. I really don't think it's the new tires, particularly since the "old" tires and the "new" tires give roughly the same results, but didn't want to rule it out (particularly while I still have a warranty). Since removing power has no effect I wouldn't suspect the differential. Besides, it really seems to be coming from the front and 2WD / 4WD makes no difference so there's no power applied to the front end anyway.

The driver side U-Joint was replace awhile ago. It failed (obviously) and made clanking noises.

Any educated guesses or wisdom? I read several other posts, including the one describing how to replace the U-Joints. Sounds like a big project. It also sounds like the best bet might be to just replace the bearings and u-joints on one side (my guess is passenger side) and see if it helps. comments?

TIA, GGK

I'd think bearings first, and possibly alignment. Also, check the front end parts (which any competent alignment person will check) for play. And although worn shocks won't make a rumble, they will contribute to tire wear.

The "old" tires showed no unusual wear. The shocks are almost new. Alignment was recently checked.

So that leads me back to the bearings, as you suggest. I read the post "How to replace ball joints/axle u-joints" (sorry, don't know how to embed a link). I guess I'll have to dig out my manual (regular store bought and not great) and renew my alldata subscription to get detailed instructions. It sounds like, in the post, they suggest if you're going to all the effort of getting in there, you might as well replace all the important or wear related parts.

Thanks for your help and suggestions.

To imbed a link, look above where you're posting, there's a small globe symbol with a chain, or link, on the lower right corner. To insert a hyperlink, highlight a word or phrase in your post, like you're going to cut and paste, click the icon and inser the address you'd like it to go to. When you're done it will look like this (http://www.automotiveforums.com/vbulletin/www.automotiveforums.com) .

Your symptoms are typical of worn Cherokee wheel bearings. Also, your mileage is about right for wheel bearing replacement. If anything, its slightly higher than average.

All Cherokees and other Jeep models that share the same front axle design typically need new bearings by the mileage you indicate.

i agree with everyone, its most likely the wheel bearing. u can check by jacking up the front end. while its in teh air, go to both sides and put on hand on the left side of the tire and the other on the right side. wiggle it around (pull left hand and push right). you should have no movement. if u do, have someone look at it while you wiggle it and see where its coming from. if the ball joints are fine, then its youre wheel bearings. here is a good write up that i used when i did mine. http://jeep.off-road.com/jeep/article/articleDetail.jsp?id=257794 (http://jeep.off-road.com/jeep/article/articleDetail.jsp?id=257794)

hope this helps.

Thank you for the help. I have the hub/bearing assembly and a 36mm socket and will change first one and then the other later this week. The shop only had one and I prefer one at a time anyway. It sounds like, based on mileage, it's not a bad idea to replace them anyway.

I've another question and don't know if I should post it here or in a separate thread. I chose here so as to include the background.

On the same problem...

While digging around and running the suggested tests I also checked out the front drive shaft. It goes from the transfer case to the front differential. It has a pair of universals on the back and one universal on the front (differential side). About 1/4 to 1/3 of the way back it also has a sort of sliding connection with a zirc fitting for grease. There is detectable play in this. This "play" allows the drive shaft to "bend" slightly. It's not much, perhaps an eighth of an inch. I've not taken it apart but can make it move a bit by pushing and or rotating various parts with the Jeep jacked up.

Is 1/8" play (shaft wobble??) too much? Seems to me I could just remove the front drive shaft and test drive the Jeep to see what, if any, difference it made. Any comments. Thanks in Advance, GGK

fyi. make sure that you use a 13mm, 12 PT socket. not the 6pt. i used a 6 pt and rounded my bolts. but i just replaced them and now are 3/4" just in case i needed to ever take them out again. hope this helps and good luck
patrick a ruth

Thank you for your help. The instructions were good and helped.

I pulled the right (passenger) side, where I thought the noise was coming from and replaced it, but no change. The Universal, on the axle drive shaft, was fine.

Over to the driver side. That one was pretty clearly bad. The process of removing the stuck brake rotor was enough to destroy it completely but it was clear long before I had the rotor off(very stuck) that there was excessive play. I finally got it all apart and wasn't completely satisfied with the Universal so I changed that as well. The bearing had completely come apart. I cleaned everything up and put it together with new parts and viola', no noise.

Note that I'd previously jacked up the front of the vehicle and listened and felt for problems without success. Perhaps more pressure on the tire, looking for wobble or shimmy might have found the problem but it probably would have also accelerated the bearing's demise. Just commenting for other readers who might have similar problems.

Thanks again. GGK

Thank you for the update.

I'm going to start a new thread but thought I'd comment here first. I fixed the bearings and the rumble was gone. However, on the highway, above about 50MPH, I was getting a vibration (or rumble). It was worse at some times than others. I had the (new) tires rebalanced and rotated but no effect. Finally, I removed the front driveshaft. That fixed the problem. I had mentioned, in this thread, that there was a little play in the shaft (it's in two pieces with the two connecting, nearer the front, with a sort of splined shaft). So, smooth and quiet at all speeds now.

Thanks again. GGK

good info for future help. thanks. keep them posting