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914World.com _ 914World Garage _ More fun stuff to do - wheel bearings?
Posted by: ThePaintedMan Nov 19 2012, 04:07 PM
Has anyone ever had a wheel bearing go bad and recognized it by sound only? I noticed a wierd high pitched, but quiet whine (almost sounded like a very quiet car alarm or beeping) coming from the rear of the car when driving to work on Friday. Yesterday I had a friend drive the car while I drove next to it to see if I could hear it from the outside, and I definitely could. It does not correlate to RPMs, and the sound stops almost immediately when the car drops below 30 mph. The only thing I can think of would be wheel bearing, specifically the left rear. Any thoughts? I would get a video of it but I doubt a microphone would pick the sound up well over the wind noise and exhaust.
-George
Posted by: SLITS Nov 19 2012, 04:12 PM
Dry / bad bearing usually "grumbles" at you in my experience, but metal to metal contact could whine.
Other .... low tranny oil ....
That's my two guesses!
Posted by: jbyron Nov 19 2012, 04:12 PM
Does it go away when turning one direction or the other?
Posted by: Rand Nov 19 2012, 04:14 PM
Grumble is a good word. Bad wheel bearings usually growl, not whine. That quiet beeping was your phone in the trunk. 
Posted by: ThePaintedMan Nov 19 2012, 04:47 PM
Lol, I knew this was going to get a few 
. No, turning and braking do not have an effect. Only dropping below 20-30 mph. Its very strange, again, sounds like an on-off "beep" sound, but quiet and more mechanical (but not grinding). I don't *think* it could be tranny fluid, as it was changed and filled less than 2 months ago, but I'll check. Good suggestion though! Any others?
Posted by: monkeyboy Nov 19 2012, 04:49 PM
Does the beeping sound slowly get faster with time? Do you owe the mafia any money?
Posted by: ThePaintedMan Nov 19 2012, 04:54 PM
Come to think of it I never did pay for that shipment!
Posted by: JawjaPorsche Nov 19 2012, 04:56 PM
Just replaced a rear wheel bearing today. Started as a roar then got worse. Here is a picture of the fried bearing.
Attached image(s)
Posted by: somd914 Nov 19 2012, 05:38 PM
I too have never had a bearing give a metal-to-metal grinding, just a growl almost like bad tire noise.
Out of curiousity does the noise go away with clutch in or coasting in neutral above 30 MPH?
On other cars I've had brake clips (springs) rub the rotor and and squeek at higher speeds, but don't see how that could be with the design of our rear brakes.
Posted by: JawjaPorsche Nov 19 2012, 05:44 PM
Jack up the back wheels and grab them. The one with the bad bearing had a lot of play.
Posted by: Madswede Nov 19 2012, 05:50 PM
Speedo cable maybe? 
Posted by: Valy Nov 19 2012, 05:50 PM
Dry / bad bearing usually "grumbles" at you in my experience, but metal to metal contact could whine.
Other .... low tranny oil ....
That's my two guesses!
Raise the wheel and turn it by hand. Bearings will usually make noise when you do that.
High pitch sounds are usually related to the disk brakes since they have higher linear velocity closer to the disk edge. Remove the wheel and check for something interfering with the disk (or maybe rim)
Posted by: URY914 Nov 19 2012, 05:58 PM
Jack it up and turn one wheel at a time.
I've changed bearings on several cars. There are a bunch of how-to threads.
Posted by: 914itis Nov 19 2012, 05:59 PM
Dry / bad bearing usually "grumbles" at you in my experience, but metal to metal contact could whine.
Other .... low tranny oil ....
That's my two guesses!
I think I have the same noise on my r/r wheel. How do you grease a dry bearing with everything mounted?
Posted by: carr914 Nov 19 2012, 06:07 PM
George, I think I have some bearings in my Toolbox
Posted by: rohar Nov 19 2012, 06:56 PM
Dry / bad bearing usually "grumbles" at you in my experience, but metal to metal contact could whine.
Other .... low tranny oil ....
That's my two guesses!
I think I have the same noise on my r/r wheel. How do you grease a dry bearing with everything mounted?
Generally with a sledge hammer. Seriously.
Posted by: SLITS Nov 19 2012, 07:58 PM
Dry / bad bearing usually "grumbles" at you in my experience, but metal to metal contact could whine.
Other .... low tranny oil ....
That's my two guesses!
I think I have the same noise on my r/r wheel. How do you grease a dry bearing with everything mounted?
Generally with a sledge hammer. Seriously.
they are a sealed, double row split bearing. No lube possible. Replace, yes.
Posted by: no1uno Nov 19 2012, 09:00 PM
I am experiencing a similar noise. I would also describe mine as a whine more than a grumble. Mine seems to be coming from the right rear. I'm hoping for wheel bearing instead of tranny. I start to hear mine around 30 and up, too. I'll check my tranny fluid this weekend to eliminate that possibility.
Posted by: URY914 Nov 19 2012, 09:32 PM
Do you hear the noise when your wife is in the car with you? 
Posted by: bandjoey Nov 19 2012, 09:53 PM
See if this fits:
I've searched this several times and there are multiple threads. Starts at over 25mph, and it's a WHOOOaaaaWHOOO oscillating noise, very faint but audible. Search for "Whining noise". Good news, it's not your wife.
Speed does not make this sound change. Braking does not make this sound change. Turning does not make the sound change. Pitch never changes. There isn't a grinding or wheel movement when checking the wheel on a jack,. and the wheel spins freely.
Consensus is a wheel bearing that has not gone bad but will, and finally changing the bearing stops the noise. Sever comments on hearing this for up to 2 years. Mine is going on for a year. Probably rear right on my car. I keep turning up the radio and will do the bearings when the other one starts whining or one starts grinding.
Posted by: jls914 Nov 19 2012, 10:16 PM
My left rear made a whining noise and would change when turning. There was also a very noticably heat difference of the two rear wheels. You didn't have to touch them to feel the difference. I changed them both at the same time. I did mine with the trailing arms still mounted on the car.
That's my experience.
Jim
Posted by: no1uno Nov 19 2012, 10:23 PM
Do you hear the noise when your wife is in the car with you?
Good One!
Posted by: Rockaria Nov 20 2012, 10:24 AM
I have almost this exact same issue. Left rear wheel. Starts whining at 30mph, no grummbling noise or feel, seems to keep the same pitch, a constant rotating whining like metal contacting, goes away instantly under 30 mph. won't go away by turning the car or pressing in the clutch, taking it out of gear. Tranny is perfect and is full of new fluid. The wheel feels solid when I jack up the tire and try to move it around.
But I have found, mine only happens when the weather is hot, like 90 degrees outside. When the weather is cool, it never whines or makes noise at all. Though I do take short trips, less than 50 miles at a time.
Posted by: ThePaintedMan Dec 5 2012, 10:32 AM
I have almost this exact same issue. Left rear wheel. Starts whining at 30mph, no grummbling noise or feel, seems to keep the same pitch, a constant rotating whining like metal contacting, goes away instantly under 30 mph. won't go away by turning the car or pressing in the clutch, taking it out of gear. Tranny is perfect and is full of new fluid. The wheel feels solid when I jack up the tire and try to move it around.
But I have found, mine only happens when the weather is hot, like 90 degrees outside. When the weather is cool, it never whines or makes noise at all. Though I do take short trips, less than 50 miles at a time.
Excellent, thanks for the input Chris. My situation sounds the exact same, except opposite. It only started doing this about a month ago when temperatures dropped. It usually doesn't start for the first few miles, but then gradually comes in as (ostensibly) the bearings begin to warm up. At this point I think its a safe bet to start with replacing the bearings - they may very well be the originals anyway.
Here is the audio. Sorry for the quality or lack thereof. I think the sound is still audible though.
-George
Posted by: Spoke Dec 5 2012, 11:21 AM
I had a similar issue after changing the rear of my 914 to 5-lug. Even seemed to change when turning. Didn't start making noise until I drove a bit.
Turns out it was the rear brake venting clearance. When the noise was happening, I touch the brakes and it changed.
Adjusted the venting clearance and the noise went away.
Posted by: bulitt Dec 5 2012, 02:07 PM
What kind of fluid are you running in your trans? I ran a Mobil 1 synthetic once in an older transaxle thinkin it was better. The trans was a whiner until I put the original spec stuff in.
Posted by: bandjoey Dec 5 2012, 02:51 PM
Warped rotor or venting but my brakes are tire and set with no drag. Whine is sorta comforting n a long trip though.
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