Wheel Bearings .......

Has anyone been experiencing wheel bearing failure with heavy track use?

Yep...left rear went at Watkins Glen two months ago (at about 3100 miles on the odometer), costing me the remaining 2 days at that track. Right front started to go at Pocono North (I suspect the BIG bump coming out of the infield onto the NASCAR bowl), and was replaced after that event. I've since added this as part of my end-of-day checklist...of course, my '996' rides a little more stiffly than stock.... - Nick [email removed]

Nick, Is this type of failure something that you could feel in the handling of the car or just by checking the play in the wheel afterwards? Karl

The left rear got progressively worse over two consecutive days at Watkins Glen. It began as a single slight "twitch" requiring a small, quick steering correction at speeds above 120 mph (basically up the front straight and just after tracking out on the back straight). I initially mistook it for wind gusts moving the car at high speed. By the end of day two, it had progressed from a twitch to a full-fledged "jump" to one side or the other -- quite exciting, and clearly not the result of wind gusts. When I put the car up on the jacks on the morning of day 3, I was amazed how much play there was with the wheel on the hub. There was no way you could miss it -- it was so bad that the rotor had to be replaced as well due to scoring. After that experience, I began checking each wheel for free play at the beginning and end of each day. The developing problem on the RF became apparent at the end of day 2 at Pocono, as I was preparing to put the car into the trailer for the trip home. The movement was not really visible, but I could feel it when I pushed/pulled on the tire with the car up on the jacks. I had my mechanic check it out, and he confirmed that the bearing was beginning to go on that corner as well, so we replaced it. There is a big difference between trying to rock a wheel with a dying or dead bearing vs. trying to rock one with a new bearing -- the new one just won't move at all. Hope this is helpful. - Nick [email removed]

Nick: What's you lap time on both Watkins Glen and Pocono North? Do PSM kicked in at all if equiped? I have a 2000 996 and tracked my car on both tracks with no problems on the rotor but the rear brake shields were both bent because of heavy use of brakes. I have stock sports suspension.

Correction: I have no problem with the bearing and the rotors. The only problem was in the rear brake heat shields

You've got mail.

What are the symptoms of a wheel bearing's going bad? I'm noticing a slight rumble coming from the rear wheel(s). Could also be that I need new tires... (DE 3X)

My (newfound) technique: jack up car, grab wheel at 12:00 and 6:00 (or 9:00 and 3:00 for rears) with heels of hands on the sidewall/rim surface, try like hell to make it click or (worse) rock by alternately pushing with each hand. Also, try to push/pull entire wheel towards/away from centerline of the car. For me, it's become a 'feel thing' -- now that I know what new bearings feel like (RIGID), I can tell if they're anything less than solid. Don't know if there's a more precise/ generally accepted technique...anyone else?

As one of the techers at Potomac region, I will weigh in with my 2cents. Our wheel bearing check is just as described in the last message. Get the car in the air and tug on the top and bottom of the tire. 12 and 6 position. There should be absolutely no play in a 996. The older models should have a "click", say 1/16 play. We also grab at 9 and 3 to check steering rack play. As an aside we had a ball joint failure in a mid-70's 911 at Summit last weekend. Something I haven't seen. Ball joints need to be checked as well. Checking involves prying on the ball joint apart to see if you have any movement.

I am not surprised to hear we are not the only ones. As far as the symptoms I have been experiencing with regard to the wheel bearings, the rears began as a rumble that gradually got louder and louder. After a few days at Pocono on the large track and the bowl in particular, I needed a new rear hub as well. As for the front bearing, while at Watkins we began to feel a slight thump, much like a slight flat spot that gradually became more and more pronounced. In our discussions with many and various people this seems to be going more and more toward the brakes and associated heat toasting the grease. Mind you, this is all just at the theory stage based on our car and some of the GT-3 cars currently running in the Club Race series. Please, … all the info we all can get will help.

I had the same problem with my RF wheel bearing. At speed, it was a dull roar then as I turned to the left a thumping became apparent- just like that mentioned in a previous post. As far as I know, my car hasen't been tracked, and the RF wasn't involved with any "curb-checks". (I bought the car with 10k on the odo) It was replaced, the only problem is my pront end feels a little different while diving into corners, like there is a response delay, but than it "jumps" at the corner, making things a little unpredictable. Anybody else notice something similar?

What does it cost to replace the bearing(s)?

I've only been through 1 wheel bearing in 3 years of club racing so they go out but not that frequently. A symptom that has not been mentioned is having to double pump your brakes. The play from the bad wheel bearing will push back the pads under hard cornering and you need to double pump to make the brakes work. They have to be pretty bad for that though. If you get the twitching Nick refered to. Espeically if it happens on a straight when you lift to shift gears, check your rear tie rods. This might be the weakest part on a 996. Motorsports finally came out with a stronger version this year. Before that all the cup cars and R/RS/RSRs used the same ones that are in our cars. Teams would have boxes of extras. I went through 4 this summer before switching to the new ones. Nick, nice car. Where do you race it? Jim

do you have the part number for the new tire rods, and can you run the motorsport ones on the street?

I don't see why you couldn't run the Motorsport tie rods on the street but, as I recall, they cost about $800 for a set. Might be overkill. I don't have a part number but anyone racing 996s will have them. Check with Kelly Moss in Madison WI or TRG. Jim

Hello, Just my 2 cents, I had a wheel bearing going bad a few months ago and there was no free play. I started to pay attention to it because of the thump-thump noise coming from the rear. As I was not 100% sure which side it was coming from I tried the free play technique that is mentioned here and I can say that there was no free play whatsoever. The replacement cost about $ 50 in parts and $ 350 in labor.

Ouch I didn't realize they'd run 8 bills. Incidently gt3/2 run the same as a 996. I was going to see about running gt3 tie rods to discover this.

Was that for ONE wheel?

Yes it was for one wheel and at a Porsche specialist. I think Porsche recommends 3-4 hours for that job so the labor just kills you. My issue was that I was not 100% sure if it was the rear left or rear right so he wanted to do both !!!! I spent 30 mns on an empty parking lot running in circles to identify where the noise was coming from. He showed me the wheel bearing and it had a clear small impact on it. I hope I am done with that because it is a pretty tough DIY job for my level. By the way my car is a Boxster S with the 18 inch turbo wheels and I have heard that due to the cornering forces it is prone to wheel bearing failures.

Ouch...I hope my bearings are okay then....

had the same problem...pretty much the same situation as "renaud". no movement at the 12 and 6 postion but there was a rotational noise and vibration coming from the front left of the car. took her in b/c she's still under warranty...i was told a wheel bearing is not covered (kind of a grey area)!! in any event, the bearing was shot and after replacing it there's no noise or vibration. now i'll feel more comfortable sliding my car around corners.