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924 howling noise - kind of like wheel bearing but not sure.

Finally took the 924S on a proper shakedown drive (i.e. with license plates and outside of my street at 10mph).. Everything feels great with the car, but I am getting a howling noise, and here are the details:

1. Definitely speed-related. The faster I go, the louder it gets, even if I kill the engine and coast.

2. It is a "solid" howl, not like most wheel bearngs I've had go bad which are more like a "whoo-whoo-whoo" with repetition. This one the tone does not change at all when driving straight.

3. Upon even the slightest jog of the steering wheel to the left, the sound is INSTANTLY totally silent, even if it is a very gentle jog that isn't transferring much if any weight. However, if I maintain a mild turn to the left (like a neighborhood street where the street winds gently), the sound comes back. During any moderate or harder left-hand turn the sound is gone.

4. Since I have new 911 wheels and tires on it, I initially thought it might be rubbing, but I have spacers on the front for clearance and confirmed that the wheels/tires are defintely not rubbing anyplace. I also switched back to my old wheel/tires (stock) which made no difference in the noise.

5. I know that wheel sounds are notorioiusly hard to located, but it REALLY sounds like the sound is from the right side of the car (more right front than right rear). But that makes no sense that the sound would go away when loading that side, if it's a wheel bearing.

6. I triple-checked the front wheel bearing lock nut tightness in the front and it's perfect, according to every how-to and manual write-up of how to set it. Front bearings were repacked and they all felt good. There is minimal to no play in the front wheels when jacked up. They spin smoothly with minor resistance and no noise whatsoever. No dust shields rubbing, no signs of any thing else rubbing

7. Rear wheels when jacked up and transmission in neutral also spin fine, no grinding, no crunching, no vibrations, no nothing.

Thoughts:

- torque tube bearings (driveshaft) - but I don't see why these would change with minor steering movements only to one side. Also I've heard this is affected by clutch in or clutch out, etc.

- diff bearings - again, don't see how a light turn only one way would cause ths

- tires - they are brand new BFG all-seasons, but I can't see why they'd make noise only when not turning left. Besides, noise remains with the other tires.

- brakes are not dragging, car coasts nicely in neutral...but could this have something to do with ebrake adjustment?

- steering-related? noise stays with engine (and PS pump) turned off and is not a steering groan, so that sounds iffy.

So that's all I can think of. Am I missing something obvious, or is the solution to start replacing wheel bearings, hoping I pick the right one first? Keeping in mind that all four of them feel good "by hand" diagnosis, spin nicely without any noise when jacked up, etc.
Old 01-28-2018, 11:22 AM
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Im not sure if this will help. But for awhile after i first got my car if i was going in a straight line my car would jutter and make a single tone noise from somewhere up front. I was told it could be steering rack float? It eventually just went away all together on mine. But that could be something worth checking out
Old 01-28-2018, 12:28 PM
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You can overinflate the tires for a test drive to help reduce tire noise. You could also have an assistant ride along and roll down the window and try to help isolate the noise to front or rear. If you have minor resistance on the wheel bearings, they are to tight IMHO. I would tighten them to spec and then back off until there is no drag.
Old 01-28-2018, 01:10 PM
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I'll check again. The fronts are literally done with the screwdriver method, so they are not tight by any means that I can think of.

Tire noise isn't an issue. When turning left I can't even hear the tires over my slightly whiney balance shaft belt (need to loosen it up a bit too...)
Old 01-28-2018, 03:58 PM
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Turn the rotor as you tighten the wheel bearing. As soon as you start to feel resistance on the rotor, back off the nut a notch. Back off and repeat a couple of times until you are comfortable it is fully seated but not dragging.

IMHO it is better to be a touch loose than too tight. As things heat up metal swells and will tighten up further. Bearings that are worn might need a little extra play.

Last edited by djnolan; 01-29-2018 at 02:10 AM..
Old 01-29-2018, 01:57 AM
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