Need help: Is this normal?

[smiley23]

Hi,

I just got 2018 M3 ZCP last week and since the beginning I've been hearing squeaking noise from the left rear wheel. It happens only sometimes and always in very low speed.

Today I checked the brakes to see if there is anything out of ordinary and I found a little "dent" on the disc (see photo below).

Since I have only 300 km on the car, should I have it checked or is it OK? Doesn't seem normal to me, but it might be my OCD.:-)

Thank you very much for help, it is driving me crazy.

[ashmostro]

If i’m viewing the picture correctly that looks like a divot on the circumference of the inner vaned portion of the disc, and that’s normal. It’s for balancing. Material is removed after production to put the rotors in balance, kind of the way you would add weight to a wheel to balance it.

[smiley23]

Ah, ok. Thank you so much! Never would have guessed that.

[ashmostro]

You bet!

[ashmostro]

Oh and by the way, you probably have a stone stuck between the back of the disc and the thermal shield behind it. Common problem.

Try bending back the heat shield a bit and see if something falls out. it could be trapped in there and take a while to come out. It's pretty annoying when it happens and indeed, very loud.

[smiley23]

Thank you very much. I already checked for any stones but couldn't find anything. However, the noise is different, it is high pitched squeaking not scraping. I will try to bed the brakes and see what happens.

[ashmostro]

Gotcha. Good luck!

[CanAutM3]

^ This