Cobalt "clunking" -- can't figure it out
 

I have a 2008 Cobalt LS with about 87,000 miles. Recently, I have started hearing a muffled "clunk" type sound when driving any speed above 15 to 20 mph, although it is the most noticeable between 30 and 45 mph. The car is totally smooth at idle. I'm not sure how else to describe it other than at about 45 mph, it sounds and feels like a helicopter is flying a couple hundred yards away. It's not a grinding sound; the frequency of the noise is about once per tire revolution. I can't tell which side of the car it's originating from, other than towards the front.

The noise can be felt in the car as well. The frequency of this noise/vibration is directly related the speed of the car. I thought maybe I had an issue with the front rotors, so I replaced them and the front brakes over the weekend, but it didn't help the issue at all. Everything else with the car appears completely normal -- am I looking at a bearing issue or something else?

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Could you please PM me your VIN number? I would like to look into this further.

You stated the rotors were replaced, did you replace them or did you take the vehicle to a dealer for replacement?

I look forward to your reply.

Louis
GM Customer Service

Did you ever figure out what the noise was? I have a '08 Cobalt with 125,000 miles on it that is making the same noise. Sounds kind of like a shock mount or something to me. Thanks, Steven

Steven,

It turned out to be a bad wheel bearing on the front driver's side. Not what I thought because it didn't sound like a wheel bearing from the few bad ones I had heard in the past, but the mechanic took care of it and it drives like it's new again. $277 to fix, so I can't really complain.