To what extent is the car brake disc worn and should be replaced?
Automobile brake plays a very important role in automobile safety, so when does the automobile brake need to be replaced? Today, fan Xiaobao will talk to you about this topic!
Brake disc wear structure:
Disc brake disc (disc) is divided into solid disc (single disc) and air duct disc (double disc). Solid disc is easy for us to understand. To put it bluntly, it is solid. As the name suggests, the air duct plate has the effect of ventilation. From the appearance, it has many holes leading to the center of the circle on the circumference, which is called air duct.
When the car is running, the air convection at the air duct can achieve the purpose of heat dissipation, which is much better than the solid heat dissipation effect. Most cars are front drive, and the frequency meter of the front plate is worn greatly, so the front air duct plate and the rear solid plate (single plate) are adopted. Of course, there are air duct plates before and after, but the manufacturing cost will not be too bad.
At present, there are disc brake, drum brake and air brake. Many older cars have drum brakes at the front and back. Many cars now have disc brakes at the front and rear. Because the heat dissipation of disc brake is better than that of drum brake, it is not easy to produce heat recession under high-speed braking, so its high-speed braking effect is good. However, in low-speed cold braking, the braking effect is not as good as drum braking. The price is more expensive than drum brake. Therefore, now many medium and high-grade cars use full disc brake, while ordinary cars use front disc and rear drum, while trucks and buses with relatively low speed and large braking force still use drum brake.
Under normal use, we should generally check the front brake disc every 60000 km and the rear brake disc every 120000 km. The maintenance cycle specified by automobile manufacturers of different models is not exactly the same, and the specific replacement cycle shall be subject to the requirements of automobile manufacturers.
There are three ways to judge whether the brake disc needs to be replaced:
1. Listen to the sound
If the light braking is accompanied by the "iron rubbing iron" or roaring sound (it may also be the effect of the running in of the brake pad at the beginning of installation), the brake pad must be replaced immediately. Because the limit marks on both sides of the brake pad have directly rubbed the brake disc, it proves that the brake pad has exceeded the limit.
In this case, when replacing the brake pad, cooperate with the inspection of the brake disc. When this sound occurs, the brake disc is often damaged and scratched. At this time, even if the new brake pad is replaced, the sound can not be eliminated. It is recommended to replace the brake disc in time.
In addition, some brake pads with poor quality have hard spots, which will also produce abnormal noise. Generally, the abnormal noise will disappear after being worn off for a period of time.
2. Look at the brake disc warning light
Usually, whether the brake disc warning light on the instrument panel is on is used as the judgment basis for whether to replace the brake disc. Generally, the indicator is off. When the brake disc fails or is excessively worn, the indicator will be on and off after repair. When the warning light is on, the brake disc has been worn to the limit, and the braking effect has decreased, which greatly affects the driving safety.
3. Look at the brake disc thickness
Most brake disc products have wear indicators, that is, three small pits will be distributed on the disc surface. Measure the depth of the small pit with a vernier caliper, which is 1.5mm. In other words, the total wear depth on both sides of the brake disc reaches 3mm. It is recommended to replace the brake disc in time.
The brake pads need to be replaced due to the following reasons:
1. As the brake pad is a consumable, it will gradually wear out in use. When it is worn to the limit position, it must be replaced, otherwise it will reduce the braking effect and even cause safety accidents;
2. Under normal driving conditions, test the brake pads every 5000 km, not only the remaining thickness, but also the wear condition of the brake pads;
3. And whether the wear degree of both sides is similar, whether the return is comfortable, etc. if abnormal conditions are found, they must be handled immediately.