Tom Trew

So, at the track last weekend I began to feel what I could best describe as a "grinding" feeling in the steering wheel on hard cornering. I suspected front wheel bearings, so took it into the shop this week. The car has seen heavy track usage for a number of years now, and the front bearings were original.

Here is the inner race of the left front bearing:


In addition to the obvious pitting, notice the discoloration of the race where the ***** run.

Here is one ball from the inner race and one from the outer race. Guess which is which.


Interestingly, the standard bearing play test where you grab the tire and test for play did not find this problem. I think it has to do with the fact that these bearings are pressed in as a unit and not likely to show slop until they are completely gone. Before replacement, I did remove the brake pads and by slowing rotating the rotor, you could hear a clicking as the ***** passed the bad spot in the race. I would recommend you do this test the next time you have your wheels off and the pads out. You might find a problem early enough to not spoil a weekend.

Tom

tj90

Great post and information!

KOAN

I was told by my mechanic (a senior guy who has been doing Porsches for decades) that he has never seen a functional failure from a worn bearing, like yours (and mine). Of course it should be fixed, but he said that the noise will get gradually worse. It isn't like a CEL, and you don't have to quit ASAP. He has never seen a bearing shatter. I developed the same noise last year at Mont Tremblant, a 14+ hr. drive away, and drove for 3 days on the track with the worn bearing and dimpled race, without anything but an uneasy feeling. I trailered the car home. It looked like yours. He fixed it.
There was no play because they were adjusted to the correct tightness. Play and race damage are two different things.

viperbob

I have seen many total bearing failures, not just simple stiff / grinding bearings. We are talking the whole wheel wobbles like a weeble. A common feeling when these things start going away is a pounding sensation when applying the brakes, and a darty kind of feeling. Also if you ever have one go bad and drive in the rain, FORGET IT. I had one on my own car go bad and at 40 MPH in the rain on the highway I thought I was going to die... About 90% of the total bearing failures I have seen have been the left rear.