Many car owners will find that the brake disc of their car is not smooth during the use of the car, and there are circles of grooves on the surface. In fact, we don't need to worry too much about this situation, we just need to take different measures according to the depth of the groove to solve the problem.

Why do brake discs have grooves?

The reason is simple, the grooves are ground out of the brake pads. Brake pads and brake discs are flat from a macroscopic point of view, but their surfaces are not flat from a microscopic point of view. During the production process of brake pads, some metal fibers are mixed inside, and various substances are mixed and evenly distributed inside the brake pads. Therefore, the friction coefficient of any position on the brake pad is not necessarily exactly the same. Therefore, it is inevitable that different parts will wear differently when braking. Therefore, with the rotation of the brake disc during braking, many concentric circles will be left on the brake disc. Marks like sanding.

Normal brake disc grooves are not obvious, they look more like fine lines, and there is no particularly obvious unevenness when touched by hand. This is a normal phenomenon and no special treatment is required. For example, the brake disc in the picture above can clearly see that there are many subtle marks on its surface, but this is a normal phenomenon. Many car brake discs on the road are like this, so there is no need to worry.

 However, some brake discs have very deep grooves, some are very wide, and have obvious bumps when touched by hand, which is abnormal wear. Sometimes when sand or other hard particles enter between the brake disc and the brake pad, it will also cause local excessive wear. Or there is a problem with the quality of the brake pad itself, and there are large hard particles inside, which will also cause abnormal wear of the brake disc. For example, a wide and deep groove like the one shown above is abnormal wear.