Causing the brake pads abnormal sound in several cases

1, Brake pads include too much metal material or impurities, cause sound.
2, During run-in period, such as replacement or new car,  after a period of time, the sound will disappear, return to normal.
3, Brake pads wear too much to the "alert" position, need to be replaced. This situation can only be replaced.
4, Brake disc "wear" irregular or quality problem, also can cause sound.
5, Brake calipers return bad or do not return, also can cause sound. need to check the caliper kit.
6, No driving for a long time, or driving often in the rain, snow etc humid environment, there may be due to the brake pads or discs rust, cause the sound, but it will be disappear much soon after driving a while.
7, Rain, snow, wind and sand dust environment, some particles (such as sand, stone, etc.) mixed in the brake pads&discs, between the film, will cause sound.