CV or wheel bearing (or both)??

[joecrum]

As of late (last 500 miles or so), there has been a low rumbling noise coming from my rear (not mine, the car's!). It has been increasing in volume over this period. I assumed it was the wheel bearings (110k miles on the car). I was ready to order a set when I thought it would be a good idea to confirm it was the bearings. I jacked up the rear end and, while in neutral, rotated the wheel. There was a mild grinding noise, as expected, but then the wheel hit some resistance and stopped turning. I rotated it past this point and it rotated 360 deg and hit that spot again. Both wheels did this. I had not noticed a rhythmical noise when driving, just a constant rumbling. It doesn't appear that the inner CV bolts are loose, but there is a little off-axis play (I assume there should be some). The boots are in great shape, too.

Any ideas on narrowing down the culprit? It seems strange that both sides seem identical. What tests can I do?

82 SC, 110k miles

Thanks,

[IROC]

It does sound like a wheel bearing issue, but it's somewhat odd that it seems to be coming from both sides as I would think it is unlikely that both wheel bearings would start to go at the same time as they are actually pretty robust. They're also a PITA to replace, so I wouldn't dive in unless you know they're bad.

One test for wheel bearing issues to notice whether the sound (the groaning) gets louder or more pronounced when you make a right or left turn. My left rear wheel bearing starting to go and it was obvious when I made any turn to the right.

If you wanted to get really fancy you could disconnect the CV from the wheel hub (possible and relatively easy on my car - not sure on yours) and see if the wheel still makes the same noise/resistance when turned. This would confirm whether it is a bearing or not. Also, there should not be any play in the CVs. The only thing you should be able to do is grab the axle and move it axially (along it's axis).

[Superman]

Wheel bearing. CV joints click when they are worn. Bearings growl. Bearing growl tends to pervade the cabin such that it is difficult to isolate the source. If you're sure it's a rear bearing, I'd be tempted to replace both and be done with it. Bearing installation tools are available which do not require removal of the trailing arm. It can be done with the suspension parts still on the car. That being the case, it would take only fifteen minutes more to do the second one, as long as you've just done the first. Be sure to torque the big nut down to at least factory spec. Not tightening this nut down enough will ruin a new bearing.

[joecrum]

This is what I was hoping to hear--wheel bearings. I'll plan to replace both wheel bearings, then. I'll check out the CV joints and confirm everything is tight.

Thank you for the responses. I'll let you know what I find.

Cheers,