996 Wheel Bearings

[ncollins]

My 02MY 996C2 has started to make a droning noise, rather like excessive tyre noise, and I suspect worn wheel bearings. The noise is coming from the rear of the car and varies depending on the length of journey, it's only done 75k so is there anything else that I should check before I order the spares? I won't be doing the job myself as I have a rather good garage in the village that I use for non porsche specialist repairs.

Nic

[5TUE]

I have been told by a Porsche speciallist that what can sound like a wheel bearing could in fact be down to the tyres especially when they are getting close to the legal limit.

Apparently Pirellis can be amongst the worst for noise resonating through the carcass of the tyre giving the impression that a wheel bearing is on the way out.

Stu.

[Rockster]

5TUE said:

I have been told by a Porsche speciallist that what can sound like a wheel bearing could in fact be down to the tyres especially when they are getting close to the legal limit.

Apparently Pirellis can be amongst the worst for noise resonating through the carcass of the tyre giving the impression that a wheel bearing is on the way out.

Stu.

Very noisy Pirelli tires masked a wheel bearing noise in my Boxster.

Slightly misaligned front tires -- from a real low speed nudge of a low curb when pulling into a hotel parking lot very late at night -- had me thinking wheel bearings in my 996 Turbo when all it proved to be was a bit of front wheel toe out but enough to make the tires howl like wheel bearings.

In short tires can make a heck of a racket, when old and hard (from heat cycling) and worn, or when ok otherwise but out of alignment.

[ncollins]

The rears are 6 month old SO2's and there was no noise until soon after I replaced the Pirellis on the front with SO2A's at Xmas but I'm almost sure that the noise is coming from the rear!

[Rockster]

ncollins said:

The rears are 6 month old SO2's and there was no noise until soon after I replaced the Pirellis on the front with SO2A's at Xmas but I'm almost sure that the noise is coming from the rear!

Tires can be worn out after 6 months and if worn out they'll be noisy.

How much tread is left?

Are the tires wearing evenly across their tread faces?

If you tell me there is good tread depth left yet and tire wear is even -- feel the tread faces for any signs of scuffing/feathering -- then the tires are less likely to be the source of the noise and a wheel bearing is more likely to be the source of the noise.

You'll have to enlist the help, the ears, of a qualified tech to ride along with you or take the car out and at a time you are sure the noise is present and let him make the call. It could very well be a rear wheel bearing is noisy and due to be replaced. All I'm saying is noisy tires can mask a true wheel bearing noise and tires out of alignment can mimic wheel bearing noise.