Ok guys my friend replaced his rear calipers on his '99 Mustang V6(disc's) and put in new pads and rotors. Now when he takes off(after they are kinda warm) after being at a dead stop, like leaving a stop sign, it makes this noise like the caliper is sticking. Almost like a moaning sound. It also does it when he goes WOT on the highway. It almost has a harmonic sound on take off. Any suggestions?