Crazy Canuck

Was at Calabogie today was on track when the car started developing a vibration from one or both rear wheels. It's there whether or not the clutch is engaged. It sounds like thump thump thump and the frequency of the thump is relative to speed travelled.

When the suspension was loaded on one side it went away.

One of the guys there thought it sounded like a flat spot on a tire. So I take off the tires, have them rebalanced. Same vibration. Took tires off, one by one and installed another set. Same vibration.

There is no play in either rear hub. Brakes looked ok. Nothing obvious looking at the car from on the ground.

Loaded the car up (it runs on its own) and dropped it off at AutoImport. I'm sure I'll find out what the deal is.

Mileage is 19500km. Weird.

P.J.S.

probably a flat tire ;-)

996FLT6

Wheel bearings? Thump sounds like tires are the issue. Wheel bearings moan but they thump too. Mike

sfbimmer

Had that same noise/issue on my old track driven e36m3... I tried trouble shooting it just like u did, but like mike said, it was a wheel bearing.

Crazy Canuck

We'll see today ...

chsu74

Have the wheel carrier checked out too. I had the same thing happen to me and it was the wheel bearing. The bad wheel bearing was left in there too long and warped the wheel carrier.

Camber

wheel bent?

Crazy Canuck

Turned out to be a bad wheel bearing. Wheel carrier is ok. As soon as I heard the noise I came in and the car was on a trailer for the ride home from the track to the service center.

I always thought bad wheel bearings squealed rather than thumped. My tech tells me a chunk came off causing the thump.

996FLT6

Nah wheel bearings don't squeal they moan then thump. Wait til your top hats on the rear shock struts start cracking- squeaks so bad it'll wake up the dead. Mike

Crazy Canuck

Hmmm ... I have some squeaking in the rear end ...

996FLT6

If u want to know if it's the hat spray liberal amounts of wd40 on top of the rear strut towers- let it sit for 30 minutes. Then drive it if no more squeaking- that's the source of the squeak. Mike

Crazy Canuck

Thanks Mike!

ron_dargenio

thanks guys, good info. Don't recall seeing that issue come up before.