Brakes sqeak when coasting not when pressed

[Matt]

Hello everyone! Lately my 1999 BMW M3’s brakes have been making a sort of scraping squeaking sound, but only when I’m coasting. As soon as I put any pressure on the pedal, the noise goes away and the brakes are silent.

Any ideas would be appreciated. It could very well be nothing but if it’s an excuse to go spend time in the backyard with my tools, it’d be a fun way to spend the weekend too.

Topic

[Mike]

That frequently happens when the brake pads are very low and the rotors have a rust ridge, but have not gone metal-to-metal yet.

[Ingvar]

Go spend some time with your tools and car. Check on pads. Glazed rotors will also do this. My guess is, you never bedded in brake pads? Resulting in glazed rotor?

[Mike]

If the car makes these noises at low to moderate speed, try driving through a quiet residential neighborhood with all your windows down and the radio off. You might be able to pinpoint the noise to the front or rear half of the car, maybe even to a particular wheel. It’ll help in deciding where to look first.

[Brian]

If a caliper guide pin is stuck that can cause the brakes to drag. Get the correct high temp brake lube and service both guide pins in each front caliper. Also, if the brake fluid is not clear or nearly clear, flush all the old fluid out. If rusty old brake fluid is left in there too long, it will rot out the hard brake lines and also potentially cause caliper pistons to stick a bit.

[Author]

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