Why is there a loud abnormal noise when braking in reverse?

[CeciliaLee]

Possible reasons for abnormal noise when braking in reverse are as follows: If it is a new car, because the brake pads and brake discs are new and still in the running-in period, they may make a slight hissing sound, which is normal and will usually disappear automatically after a few hundred kilometers. There may be foreign objects between the brake pads and brake discs, such as small particles like sand or small stones entering between the discs, which can cause a hissing sound. Extension: 1. The brake disc and brake pads may stick together due to rust, causing abnormal noise. This usually happens after driving in the rain and then leaving the car unused for a few days. The brake disc and brake pads rust and stick together, and when you start driving again, there will be abnormal noise, which is also normal. 2. In winter, if the brake pads and brake discs are exposed to cold for a long time, ice may form at the contact points. When starting the car, the slight noise caused by the ice melting is also a normal phenomenon.