545svk

How to identify whether a wheel bearing is failing?
I have a vibration coming through the floor at 90 to 100 km/h that feels like a rear wheel has lost it's balancing weights. I checked the wheels and that is not the problem.
Can it be bearings, or something else? There is no sounds or any other symptoms.
Thanks

GregBBRD

Lots of noise, when wheel bearing fails.

Have the tires inspected for a separation and have them rebalanced.

Rob M Budd

Had the same symptom on my GTS. And did what Greg suggests.
Two were out of balance and found one bent rim.
Now fixed and smooth ride is back.

Jerry Feather

I had exactly the same symptoms in my 87 and found that it was in fact the wheel bearing. It was going bad but not yet torn up , but it had hammered a groove around the hub shaft about a 64th deep and destroyed it. It is a pretty big job to change the rear wheel bearing, but you need to.

I found my bearing failure early in a 500 mile trip to Denver for a Porsche breakfast event and I could not go over 65 mph without the vibration just as you describe. However, the most telling thing about the bearing was when I got back and was in some turns in the street very near my home, when I turned one of the corners at corner speed that wheel bearing really gave out some growling, probably much like Gred B suggests. Go try a few low speed corners in you car; it will talk to you.

There are several threads on here about changing the rear Wheel Bearings. I would change them both while you are at it.

One other thing I remember about mine is that when I started into the change I found that the axle nut on the failed bearing side was not very tight. It was a little more than finger tight, but it took no torque with a wrench to remeove it. I couldn't tell if that was installed that way and that that might have given rise to the failure or if came loose from the vibrations.

Petza914

Starts by making a grumbling noise and usually changes pitch as you turn left.or right and the load on it changes.

928NOOBIE

Please Delete.