: low speed noise



dan1166
03-26-09, 09:15 PM
I am the proud owner of a 2006 STS. What a great car. Last week I encountered a strange noise coming from the left front wheel.

I was caught up in a traffic jam at the Bristol Nascar Race. It was stop and go for about an hour. Between 15MPH and 25MPH, I get a bumping noise from the left front wheel assembly. After 25MPH, the noise goes away. The car runs as smooth as silk at any speed.;30, 50, 70, 80. No noise. My first thought was brakes. The brakes do not chatter at any speed or stopping on a downgrade. This is really strange. I check with my Cadillac dealer, and he said there were no service bulletins related to this problem.

My question is; did anyone on this forum experience this sort of problem, and if so what was it, and how was it rectified? You thoughts and opinions would be greatly appreciated. Thanks

Dan, the STS Man

EChas3
03-26-09, 09:29 PM
No vibration in the steering wheel at any speed? Does the frequency increase with the speed 15-25? If so it could be a belt separation.

Can you reproduce it now?

I'd have heard the cheers from here if you'd run over the 18's driver... :devil:

dan1166
03-26-09, 10:05 PM
No Vibrations in the steering wheel,and yes, I can reproduce the noise. I did hear this noise sometime ago, but this time I heard it alot due to the traffic jam I was in. The car has only 16,000 miles on it.

Thanks for your input

Dan, the STS Man

dan1166
03-26-09, 10:07 PM
One more thing; The frequency does increase with the speed, but goes away at 25 MPH

Thanks

Dan, the STS Man

turnerbend
03-26-09, 10:20 PM
Put the car on a jack and rotate the wheel and see if the noise is there.

EChas3
03-27-09, 10:25 AM
If the wheel turns freely (or with constant resistance) while off the ground it's much less likely to be a wheel bearing or brake-related. If there is any sort of increased resistance at one point as you spin the wheel the problem is not likely to be the tire or wheel.

I would be surprised by a warped or otherwise flawed disk rotor because you don't report steering wheel vibration. Do you have any symptoms while braking? A pulsating brake pedal? (Excepting ABS or Stability Control.)

Is this an All Wheel Drive model? If not, that eliminates a lot of drive-line components. If it is, you'll probably meet with a lot of resistance when spinning the wheel, even in neutral. You could then raise both front wheels...

If you're under warranty & it's easy to reproduce, schedule a dealer visit. In this area, things are really slow at our dealer's service department. My wife needed to swap her Blizzak's for Summer Tires and they did it the day after her call and for less $ than nearby independent shops, plus they cared for the TPMS. It may be a pain to swap tires twice a year but a semi-annual rotation and road-force balance should prolong tire life.

Sight unseen, I suspect a tire belt separation because it doesn't take much to make a sound and they can be very speed sensitive. If you do jack it up, do a thorough examination of the tire for bumps and/or wear patterns.

DO NOT GET UNDER THE CAR WHILE IT IS ONLY SUPPORTED BY THE JACK.

dan1166
03-28-09, 08:51 AM
The car is a rear wheel drive, with 16,000 miles on it. I always heard a slight thumping noise, but it seems to be getting worse. I guess I will follow your advise. Let the dealer find the problem. Maybe I will try rotating the front tires, (rears are a different size), left to right to see if the noise changes or moves to the other side of the car. Just trying to pin point the origin. Thanks to all for all of your input

Dan