I have just installed a set of 8 inch El camino discs on my Trek MTB. I have a mojor problem with a high pitch ringing coming from the front disc as I am generating speed soon after getting going. Definately no pads are touching the discs and the disc runs freely.
It's like the disc is under stress as the front wheel gathers speed. The sound disappears at high speed.
Was thinking of just re-mounting the disc and see what happens.