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Sounds like a flat tire...but it isn't

05-22-2009, 06:14 AM
To bring you up-to-date...we were given a 1996 Grand Am that needed a lot of work.

My son got his license, and has been driving the car to school for a couple of weeks.

He says that "the back left tire sounds like a flat tire the first couple of miles. It makes a thumping noise." (It's not flat.)

Now, I had the tires checked out by my favorite tire guy, and he said they were good. However, he asked me if the car had been stored for a long time because the tires had flat spots on them. He said that would eventually go away. Otherwise, the tires were in good shape.

What worries me is the fact that THAT wheel had a brake that was grabbing badly, so I took the brakes apart and installed a new brake cylinder, thinking that the cylinder must have been leaking.

I'm wondering if it's possible that the brake drum is out-of-round causing some kind of noise until it warms up.

Anyway, I'm leaning toward this either being the flat spot on the tire or something having to do with my reassembly of the brakes. (I didn't put any new parts in. Everything except the brake cylinder was already pretty new.)

Is there anything else I should be checking on? What would you do?

05-22-2009, 12:59 PM
Both sound like possibilities. Why don't you put the spare on that back tire thats making the most noise and drive the car. If the noise goes away then you know its the tire if it's still their then you know too look more into the brake assembly.

05-24-2009, 05:00 PM
This wound up being an out-of-round brake drum.

Replaced the brake drum, and the brake no longer grabs and the car no longer sounds/feels like it has a flat.

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