How to determine if the brake disc needs to be replaced:

1. Listening to sound

If the brake is applied at the same time as the "iron rustle" or noise (it may be due to the grinding of the brake pads at the beginning of installation), the brake pads must be replaced immediately. Because the limit mark on both sides of the brake pad has directly rubbed against the brake disc, it proves that the brake pad has exceeded the limit. In this situation, the brake disc should be replaced at the same time with the inspection of the brake disc. When this sound happens, the brake disc is often damaged and scratches appear. Even if the brake disc is replaced, the sound still cannot be eliminated. In addition, some of the brake pads of poor quality have hard points, which can also produce abnormal sound. Generally, such abnormal sound will disappear after being worn away for a period of time.

2. Whether or not the brake disc warning light on the dashboard is usually used as the basis for judging whether the brake disc should be replaced

Generally, the indicator light is in an off state. When the brake disc fails or wears out too much, the light will be on and put out after repair. When the warning light is on, the brake disc has worn to the limit and the braking effect has decreased, which greatly affects the safety of the vehicle. Therefore, we suggest to check the brake disc wear status regularly to see if it can be used, instead of just trusting the warning light.

3. See the thickness

Most brake disc products have wear indicators, which are three small pits on the surface of the disc. Use the vernier caliper to measure the depth of the pit is 1.5mm. That is to say, the total wear depth of the brake disc on both sides reaches 3mm. It is recommended to replace the brake disc in time when the quasi-wear and complete wear as shown in the following figure appears. Not all brake discs have wear indicators, of course. We can tell the approximate depth by touching the edge of the disc with our fingers. Generally speaking, if the total wear depth of the brake disc on both sides reaches 3mm, the brake disc should be replaced in time. In addition, when the two side brake discs (drums) are used in different brands and different specifications, resulting in different friction effects, resulting in different braking effects on both sides, which will lead to off-track braking, poor braking effect and poor braking distance. Therefore, it is recommended that both sides of coaxial brake pads (hoof) be replaced at the same time to ensure the same braking effect.