fhp911

Gang,

Maybe GT3 are different, but my prior car, an '84 911 suffered catastrophic wheel bearing failure at Pocono a few years go. There was no warning -- no noise at all and then the entire front left just went -- boom!


Fortunately, I was able to catch it in the turn and limp back to the pits. The bearing was completely shot and I needed a tow to my shop.

Moral: test the bearings a few times per season. (Wheel wobble test.) I've been careful ever since.

jwas1

If anyone is still following this thread, I am the original owner of a 1985 911 cabriolet with 75,000 miles. Never raced. For the past several months there has been a low frequency rumble in the rear best heard at about 30mph. There with car in or out of gear. Is this most likely bearings? What happens if I do not replace them? Rarely drive over 75mph these days.

dan212

Wheel bearings are a wear item for track cars. Wear is greater with higher lateral loads. With track oriented setups and tires, you'll see higher loads and wear. The left side is more likely to go than the right given clockwise tracks. No point in replacing them as preventative service unless you know that the bearings are nearing end of life (see below), but when I replace the left side bearings, I do the right side as well. I do that because I like to service left and right side equally and because the right side bearings are likely to fail soon after the left and I might as well do them at the same time.

Symptoms are a thrumming sound typically under lateral load. If you hear it under straight line loads, they should be replaced ASAP. I wear hearing protection (doesn't everyone?) and if I hear it the bearings are really bad. I'll sometimes notice a light thrumming only when reviewing video - something to consider..

Hard to measure wear as "seasons".. Depends on how many days that is. But I'd say that 30-40 days will kill the bearings on a well set up car.

TurboCup87

Sounds relatively likely. Should be more noticeable in curves. My rears in a heavily tracked 944T wore out after about 10K track miles.

Crazy Canuck

I've had 2 go on the driver's side. Car has about 14,000 miles on it. Mostly track.

Mine groaned/thumped.

Macster

First you need to clearly id from where the noise is coming from. While it might be a wheel bearing it might be something else: A half-shaft's CV bearing making the noise for example.

If a bearing (wheel or CV) is making noise that's sufficient reason to replace the noisy bearing.

One shouldn't continue to use a car until the bearing fails. I had a CV bearing fail in a vehicle (Dodge pick up truck) of mine -- the bearing was *new* the work done at a dealer to replace the original CV bearings -- and when the bearing let go the CV joint failed (at the tranny end of the driveshaft) and the drive shaft started whipped around and busted the tranny case. A very expensive tranny case. Ruined the transmssion (a heavy duty 727 auto). The dealer not only replaced the damaged driveshaft but replaced the tranny at no cost to me.

Get the source of the noise id'd and then properly address the source of the noise.

Sincerely,

Macster.

multi21

Never had to replace the bearings on my GT3, but my 944 spec race car has been through a lot in a season and a half. As others have said, you'll hear it before you feel it and it's usually on a left or right turn.

One of the ways to check when you hear something is to squat down put your hands at the top of the wheel at a 10 and 2 o'clock position and shake back and forth. If there is movement, there is an issue.

I highly recommend changing all 4 wheel bearings when there is a problem with one as the others are probably close to giving out as well. Ask me how I know....

fhp911

My experience is more complex.

In my '04 GT3, at a track event at WGI I started hearing the types of noises described my other posts in this thread. The left front bearing was shot -- I was able to get it fixed and only lost 1 full track day. (A PLUG FOR PARMENTER in Watkins Glen!!)

BUT, in my former '84 911 with no warning (audible or otherwise) at Pocono, the bearing WENT - POW! -- and seized and ruined my left front suspension. I was able to limp back to the pits.

To make the wheel bearing issue trickier, my raceshop had checked the bearings in both cars (or told me they did) just a few months before the failures.

joe1973

Hey CT...
Just ask Danny Jacobs how much he charges to replace. Heard it's not much and if you're on 2nd or 3rd year tracking your car without replacing, just pay the amount which could save you blowing a whole DE weekend that costs $300 fee, $200 hotel, $??? pads, tires, etc.

fhp911

In fact, it was Dan Jacobs who had a spare wheel bearing in his truck when I so desperately needed one at Watkins Glen. (Parmenter in WG did the replacement.)

Thanks to him, I was able to get back on the track; otherwise I would have had pretty close to a complete bust.