（1） The noise caused by human factors after replacing the original car brake pads
1. It may be that the repairman installed the brake pads on the wrong side, and when removing them, it can be seen that there are only local friction marks on the surface of the brake pads. At this point, you will have to dismantle and reinstall it at the 4S store.
2. After driving for a period of time, it suddenly makes a noise, mostly due to hard objects such as sand, iron scraps, etc. on the road being sandwiched on the brake pads when pressing the brake. In this case, you can go to the 4S store for cleaning.
3. Due to issues with manufacturers, the size of the friction blocks for the same model of brake pads is inconsistent, especially the width of the friction blocks. Some manufacturers may deviate by up to three millimeters in size. This causes the surface of the brake disc to appear smooth, but larger brake pads will also make a noise when installed on a brake disc that has been rubbed by smaller brake pads. When encountering such a situation, you need to first drive the disc. If the disc is not available, it can be driven for a period of time, and once the traces match, it will not sound.
（2） Noise caused by product factors such as brake pad material
If the material of the brake pads is relatively hard and poor, it is prohibited to use brake pads containing asbestos according to regulations, but some small manufacturers are still producing and selling brake pads containing asbestos. Although semi metal asbestos free brake pads have a long driving range, which is beneficial for environmental protection and personal health, the material is relatively hard. However, asbestos brake pads, due to their soft material, often do not make a sound even if there are scratches on the brake disc, and the braking feeling is soft. If the noise is caused by this situation, you can only replace them with new pads.
（3） Abnormal brake pad noise caused by damaged disc
The damaged disc referred to here refers to the damaged disc when the surface of the brake disc is smooth and flat. In addition to foreign objects caught by the brake pads during driving, it is also caused by uneven mixing during the manufacturer's production process. Nowadays, due to cost reasons, the hardness of brake discs is not as high as before, which leads to semi metal brake pads being particularly prone to damaging the discs and producing abnormal noises.
（4） Abnormal sound of brake pads caused by debris or detachment of friction blocks
1. Long term braking can easily cause debris or detachment. This situation mainly occurs in mountainous areas and highways. Due to the steep and long slopes in mountainous areas. Experienced drivers may use the brakes to go downhill, but novice drivers often brake continuously for a long time, which can easily cause the plates to burn, fall off, or block, or the driver often travels faster than the safe speed on highways. In emergency situations, the brakes often lose their effectiveness and must be continuously applied. This type of long-term braking often causes the brake pads to burn, fall off debris, and detach, resulting in abnormal noise from the brake pads
2. If the brake caliper does not return for a long time, it will cause the temperature of the brake pads to be too high, leading to erosion and deterioration of the friction material, or adhesive failure, resulting in abnormal noise.
（5） Rust on the brake wheel cylinder
If the brake oil is not replaced for a long time, the oil quality will deteriorate, and the moisture in the oil will react with the wheel cylinder (cast iron) to rust Resulting in friction and abnormal noise
（6） Hand killing wire not working
If one of the two hand brake cables is not working, it will cause abnormal brake pads. At this time, you can adjust or replace the hand brake cable.
（7） Brake master cylinder
