Diff or Wheel bearing noise?

[89Vette]

FWIW, my recently acquired VX had a similar 'whine' when decelerating. A noticeable almost rubbing like noise when you let off the gas at low speeds, and seemed to be worse at higher speeds above 40 MPH.

I've dug around the site some and read a few posts on the topic. One of the first questions asked of me was if the tires were mismatched. My front and rear tires were not only different brands and tread patterns when I picked it up, but the wear pattern was very uneven due to severe misalignment and lack of rotation.

It was suggested to me that tires on the VX are critical to the TOD system functioning properly. If tires are severely mismatched or unevenly worn (as mine were) it can cause bad sensor readings and lead to trouble in the transfer case.

In many threads I read, users/owners tended to notice this noise more, or for the first time immediately after lifting their VXs and putting on larger tires/wheels.

I'm not sure exactly what the issue is, if there are multiple problems described here with similar symptoms but different root causes, or what the ultimate solution is, but in all cases I've read about tire condition, size, and lifts seemed to play a role in triggering or exacerbating similarly described problems.

I changed my tires out for a near stock 255/60/18 on an aftermarket 18x9 rim, and most if not all of the sound I heard when decelerating is gone. I'm not entirely convinced that there isn't a 'problem' still lurking under there somewhere, but the new wheels and tires appear to have minimized the symptom in my case.

In any event, I'm very interested to see what others have to add on this topic. When I first encountered the rubbing/whining sound there was a distinct vibration I could feel as well. I thought it could be anything from a bad CV or drive shaft to a problem in the transfer case. I guess I'm still a little skeptical that new tires and wheels have truly eliminated the problem, and wonder if the larger tires, wheels, and lifts or worn tires put more stress on an already weak component or if bad sensor readings and TOD settings are really the culprit here.

I read that too. In your case, I think you'd be wise to mount four new, balanced tires to see what happens. But, mis-matched tires should exhibit problematic sounds under many conditions (vs just in decel). I don't think that's your "solution", but having four matched tires, will probably rid you of some road/tire noise.

FWIW, I asked a machine shop about this today. The head machinist told me how you could tell which of 1) the ring bearings, 2) outer pinion bearing, or 3) inner pinion bearings were failing.

If the sound occurs fairly evenly at all speeds, the ring bearings (aka carrier bearings) are probably going bad.

If the sound occurs under accelleration, the inner bearing (base of pinion) would be seeing the most pressure.

Otherwise, under decel, the outer bearing (nose of the pinion) would be seeing the most pressure.

[djvx]

Otherwise, under decel, the outer bearing (nose of the pinion) would be seeing the most pressure.[/QUOTE]

What would the "fix" be for this- did the mechanic say?

[LittleBeast]

My noise at highway speeds when I let off the accelerator is getting almost unbearable. It seems to have gotten significantly worse the higher I lifted the suspension lift, greasing the grease points only seems to help for a day or so