I've got a 2013 JCW Cooper HT with the stock JCW 12-inch drilled brakes and 17-inch run-flat tires. I've only had my JCW for 4 months. I noticed over the weekend there is a noticeable groove in the rotor on the right rear along with some grinding and squealing noises, which is kind of blowing my mind right now. I've got a service appt set up, but am trying to find out possible causes for the groove. Don't know much about brakes in general, so forgive me if I sound a bit ignorant here.

Anything y'all can offer would help.

Many thanks!

 

Something got wedged between the rotor and the caliper or pads are worn out(I doubt).

 

That's also what I've been told (something wedges between rotor and caliper). Also a possibility the gap between caliper and rotor needs to be adjusted. At any rate, COKESTR is headed to the shop soon to get this taken care of.

Thanks for your response.

 

Most likely a rock got in there. I have seen it happen before. I doubt it was something related to manufacturing of the car.