Maybe your rotors are touching the dust shield. I had this issue when I replaced my rear rotors, they were rubbing on a lip on the inside of the dust shield. Based on posts here, I'm not the only one this has happened to. Grinding the dust shield down a little solved the issue.

 

yep, going through this thread seeing if anyone else had this issue and thats what i was going to say. happened to mine as well, but mine only sounded off in heavy cornering situations.. when you pull the rotors off the dust shield sits into a little groove and if it gets out of wack at all it can touch. youll see a fresh metal spot on the edge of the dust shield where the rotor has been making contact, a little grinder work with a flap wheel and blammo, problem solved.