mroach23

Recently (last few days) my '01 Mustang GT has been making a very loud grind/squeal noise first thing in the morning when I back out of the driveway. It sounds like the noise you hear when a big rig applies the brakes ( a very low-pitched metallic sound). The noise is faint when I back out of the carport, and gets very loud as I turn (in reverse). The rest of the day the noise is gone - even after the car sits all day (so I think it's related to the cold somehow). I recently ran over some rocks that had fallen on the highway while I was on a road trip, so it's possible one of the rocks physically damaged something underneath, but I haven't been able to find anything so far. Sound seems to come from the rear - I checked all the brake pads/ rotors, and they're fine. Any suggestions?

The car is still under warranty, but if I take it in and they find physical damage they may not cover it, so I'd like to diagnose the problem myself (with your help, of course)...

big1

If you only hear the noise in the morning the problem is most likely rust.
Believe it or not rust can form on your rotor's over night creating the grinding sound that you are hearing in the morning.
I'll almost bet that you don't hear the noise after applying the brake's just once. Do ya???

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mroach23

I can't see any rust, but I'll check it out...

But what would cause the sound to get really loud as I turn? (even when the brakes are not applied?)

Perhaps if something else under the car got damaged, it's rusting over night....

This sound is much louder than when depleted brake pads grind the rotor, and much lower-pitched than any kind of brake squeal I've ever heard.

I'll continue to investigate, and any additional suggestions would be greatly appreciated.

bullitt shott

I have had a simalar experience with a wide tire car. The front, inner wheel well cover ( that big piece of plastic that protects the engine from tire thrown debris) can get loose, especially if you have run over something big. When you are driving forward, the tire just runs down the edge, and you never hear it. BUT in reverse, the tire tread grabs the leading bottom edge of the cover, and , well, like a a baseball card in your bike tire spokes, it makes a sound. When you turn the wheel in our out, while in reverse, it will get REAL loud. Check it ou. Let me know.