I am in the middle of a brake job and i have gotten to my rear rotors. There is a strange round peice in the rotor that I don't know what it does. I have never seen it before and the front rotors do not have it. I think it has something to do with the emergency brake but I am not sure. I have to change the rotors, and I figured I'd post this and get help before I just remove them and screw something up. any help would be great. thanks

 

Does it have a slot in it? If so it's the plug for adjusting the parking brake. You can remove it & just replace the rear rotors. However you will now have to remove the rear rotors if you ever want to adjust the parking brake at the wheels. This is for major adjustment, you can do minor adjustment at the pedal, or lever if it's a 6MT.