loud howling from rear brakes
 

my 2011 3 sport rear brakes howl loudly when in reverse.at first it occurred in damp weather only and would stop after a short trip down the road but now it is there all of the time wet or dry. A local brake shop examined them and took them apart but could not explain why the brakes would howl as the rotors were not warped and no oxidising was evident. Can anybody help with an answer.

Does it only happen on full moons?

What speed/speeds does it make the noise at?

the noise begins as soon as the car begins to back up but never in a forward gear.

problem solved. the noise was caused by a caliper sticking in damp weather and not in dry weather for some reason,but lately it stuck all the time. go figure.

It's a shame the brake shop didn't pick up on it. Glad you found the cause in the end.

Well at the very least it will make me do my homework on a shop that will work on my car.