Woo Woo Woo sound from rear end....maybe rear wheel bearing?

[Chris Tallon]

Hello all,

I've recently noticed a Helicoptor type sound (WooWooWoo) coming from the rear of the car as I'm driving down a mountain road. I put the car in Neutral and coast and can hear it fairly consistantly. I've asked around a bit and the general consensus is rear wheel bearing noise. The problem is that I am having difficulty isolating which side it may be coming from. Any of you had a simialr experience and if so, any tips on isolating which side? Thanks in advance.

Chris

[Soterik]

1) Look on the backside of the wheels for any leakage. 2) After a run, see if either hub is warmer than the other. 3) Put it in the air and spin both rear wheels, sometimes you can just hear the thing.

Whenever I've bought a car from someone, wheel bearings are something I usually have done immedietly. They seem to be wayy down the list of regular maintenance items that I have seen many prevous owners do. Don't ask how I know, I've been semi-stranded 3 times on bringing "new" cars home......


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[larwik]

Chris....I have had similar sounds and concern....until I applied the parking brake slightly when in reverse...it turned out to be the "shoes" for the p-brake dragging a little...Hopefully you too get of this easy... / Lars...

[ttweed]

The problem is that I am having difficulty isolating which side it may be coming from.

Chris-
Isolating it is tricky from the cabin while driving. Noises can fool you. I have had front wheel bearing noise sound like it was coming from the rear at speed. Is the sound worse when turning one way or the other? That may help isolate it. Have you tried just grabbing the top of the tire when the car is parked and shaking it in and out to feel any play? That is how we check bearings in tech inspection for driving events. The fronts may have a slight bit of play, depending on adjustment and spindle wear, but the rears are usually rock solid. If there is any play at all, the bearing may be bad.

You should also check the CVs, as they could be dry and making a whirring sound like you describe. A brake pad hanging up can cause it, too.

TT

[Chris Tallon]

Erik, Lars,

Thanks for your help. I'll investigate further and report back.

Chris

[Chris Tallon]

Tom,

Thanks to you as well.

[EARLY911ZOO]

I've changed out a set of wheels once and the "weird " sound was gone!
put the old wheels back on and the noise was back!! flat spot on one tire

[911quest]

If the tires are cupped that is probaly the reason for the sound like said above the best way to determine a wheel bearing is if it goes away as you turn the wheel what you are doing is loading and unloading the bearing

[Chris Tallon]

Thanks Zoo and 911quest,

I don't think it's the tires. I have two sets and this occurs with either set mounted. As for the bearings in the rear, As I turn in on either side to load the car the sound becomes more noticable, doesn't matter which side. What about the CV's as someone else mentioned? Any tells there while driving? I'm going to put the car up on stands tonight and spin the rear wheels a little. It has LSD so it won't be as easy as freewheeling, but maybe I'll hear some clue.

Thanks all for your input. I'll report back with findings later.

Cheers........

[Chris Tallon]

Just returned from the garage and in the air, on jack stands, I can't hear the sound. I spun both wheels for a long while and couldn't hear a thing. I placed the car back on the ground and coasted the car downhill with the motor off and could hear the sound again. As I turned the car left and right the sound got a little louder, did not matter which direction I turned the car.

I took it back to the garage and rocked all four wheels for any hint of a loose bearing. Rears were rock solid, but front left is a little loose, so I'll adjust that and recheck over the weekend. I suspect though that this will not be the culprit. I'm thinking maybe CV's are dry as someone posted earlier.....Hmmmmm.....

Thanks again guys................