First off my car is an 08 Cobalt SS. When its really cold or especially when its cold and wet my rear brake whine. It almost sounds like a semi trying to stop. If I'm doing stop and go driving where I'm constantly using the brakes the sound stops but if I'm on the highway it always happens since they aren't used as much. Also it happens after the cars sat for a little bit. I replaced the pads and it still happened, and after the install of the new pads I took a long trip and I could hear the brake whining while i was driving, but it only happened once. I'm not sure if I should try to replace the rears again or maybe its a bad caliper?

 

check your install; if the pistons were not wound back into the caliper enough the rear brakes may be dragging. good luck.

 

Got any suggestions for me? When it rains my back brakes make an almost clicking noise but only when or after raining. If I lightly put on the e break it completely stops for a few minutes then comes back but does not make this noise when it doesn't rain.

 

Pistons were wound all the way. I also noticed the pedal gets stiff when it makes the noise.

 

My car does this only in reverse when the car is cold in the morning. Its more than likely just some build up on the rotors. That wat ive always assumed anyway. Never worried to much about it and its been there since i got the car.