Why does the car make abnormal noises when braking?

[AaronFitz]

Excessive clearance between the piston and cylinder wall; the piston pin or connecting rod bearing is assembled too tightly; excessive clearance between the tappet and its guide hole; wear of the cam profile, etc. Below are the related causes: New car break-in period: Generally, new cars may make noises during the break-in period because the brake pads and discs need time to break in, so the noise will disappear after some driving. Foreign objects between the brake pad and disc: Sand and other foreign objects often get between the brake pad and disc, causing noises when braking. Brake pad causing abnormal noises: Brake pads are made of a mixture of materials such as graphite, resin, and iron powder. When the surface of the brake pad encounters metal particles, it can cause noises during braking.