[Eli]

Hi,

I posted this on Pelican earlier.

My 87 Targa has developed a somewhat of a thumping noise coming from the rear at low speeds. When driving above 40-50 mph the thumping disapears.
When driving at low speeds it's just a constant "thump, thump, thump". I can even feel slight vibration through the chassis.

Today I was under the car checking CV joints, etc. All are intact and looked almost new. I went through the records and sure enough CV boots were replaced at the same time a clutch job was performed about 20K miles back.
Drove the car some more, the noise can only be heard when going in second gear about 20 MPH, it's distinctive whirring coming from the drive train. Almost sounds like a bad wheel bearing, except the wheel bearing noise ususally doesn't go away....
Any ideas? Anyone local willing to lend an ear?

[Mackpipes]

What brand of tires are you running? Check each tire for delamination or bulging sidewalls. Kumho's have had trouble with this in the past. Although, I just replaced the Michelins (sp) on our Saab for this reason as well. I hope it's a simple fix whatever it is.

[Eli]

Thanks Ted. Chances are it is the tires. I'll drive a bit and see if the noise gets worse

[William Miller]

I found my rear bearing were toast. Couldn't tell how bad untill the break pads and rear rotor were removed. The pads and brake shoes can hold the hub pretty good. I noticed something seemed loose back there because the suspension was pretty sloppy. I was really supprised how bad the bearings were and I didn't notice any noise.

You may also need to re-pack or add grease to the CV joints.

[4Runner]

I went through similar problem as you described with my 951. I replaced 4 tires and the car is quite now.

[APKhaos]

Waaaay back when I first had the 911, a strange thumping noise developed. After some hours of diagnostics, a local indie shop determined that the pass side CV was the problem. One new axle assy and $600+ later, the thumping was unchanged.

Fitted another pair of rear wheels & tires..........no thumping! TA DAAA!

That was one the the seminal events that made me forever determined to trust my own diagnosis, as revert to a shop as a course of last resort and even then to do so only with very tight specs on what I wanted done.

[BlackTalon]

Wow, I had the same problem a few years back. I had some brake work done, and upon completion developed a really bad vibration in the rear of the car. Took it back to the shop, and they determined the parking brake shoes were deteriorated (although they didn't notice when they replaced the rotors...). Another $350+ later, I picked up the car and had the same problem on the way home. They then kept the car for a week or so and supposedly could not duplicate the problem. I told them their tech could drive it home every night so he would experience the problem, but they never did.

I went back to the shop to pick up the car, and they decided to pull the rear tires and look under the back end one more time. When they removed the tires, I immediately noticed an area on one where a couple belts were showing (they did not notice this during all the times the wheels were pulled/ reinstalled). Had new tires on it two days later, and the vibration was finally gone! Needless to say, this really soured me on the repair shop, and I soon after started using Ivan at IMA.