Good Morning, all:

Ah yes, the winter. The time of year when working under the car doesn't require a cold beer, but a warm brandy....

The car: 1999.5 A4 2.8, box stock. 134k miles on the clock.

The problem: I've got a roar coming from the rear end that sounds all the world like a wheel bearing going, except that I replaced both bearings about 4k miles ago, and the noise isn't directional. It sounds like it's coming right from the middle of the rear of the car. It is speed senstitive; not really noticeable until about 30mph, then it rears its ugly head.
I'm not sure how to diagnose the problem. I figure it's either a rear diff issue (pinion misalignment?) or the driveshaft carrier bearing. Or, perhaps, the rear U-joint on the driveshaft? Is there any way to definitely tell which one is causing the problem?

Thanks much!
-Red

 

Try moving both rear tires to the front just to easily eliminate them from being the cause. If they aren't, then it could be a diff issue - possibly carrier bearings as well. Also, it's possible that the bearings are shot again - on a friend's car the new bearings were bad right out of the box - they had about 1mm of play in them. You may have gotten bad ones.

 

ya i have gotten new wheel bearings and they only lasted about 4k if that.

 

I had the same issue I replace my wheel bearings and no more than two months went by and started hearing the howling again so I puled them apart and sure enough it was the bearings, I went with the cheapest ones I could find so this time I replaced them with a little more pricey ones and have been driving on them for 2 1/2 years now.

 

Thanks for the comments, all! I think I'm going to take a wait-and-see if one side gets worse than the other. I purchased the bearings from Blauparts, and they were German, not crap, so I figured they'd be ok. Then again, the shop that put them in could have beaten the snot of of them on install, or it could have been simple bad luck. I'll let you know if a few weeks!

 

Carefull with some of that "made in Germany" stuff. Hamburg Technic on ebay for instance advertises everything as made in Germany. They have an office in Germany, but if you do a little digging their stuff is made in China, South Korea and Turkey. There's a loophole in German law apparently.

Sometimes the stuff with the Audi rings with "made in Slovenia" is better, cause it's made to Audi's specs. I really do hope that this is not the case with your wheel bearings, but I've found out the hard way that there's a lot of shady companies out there.