Brake disc wear structure:

Disc brake discs (discs) are divided into solid discs (single-plate discs) and duct discs (double-plate discs). Solid plate type is relatively easy for us to understand. To put it simply, it is solid. The air duct coil, as the name suggests, has the function of ventilation. From the outside, it has many holes on the circumference leading to the center of the circle, which are called air ducts.

When a car is in motion, the air convection through the air duct achieves the purpose of heat dissipation, which is much better than solid heat dissipation. Most cars are front-wheel drive. The front disc wears out more due to the use of frequency meters, so a front air duct disc and a rear solid disc (single-plate disc) are adopted. Of course, there are also those with air ducts on both the front and back, but the manufacturing cost won't be too different.

Currently, there are disc brakes, drum brakes and air brakes. Many older cars have disc brakes at the front and drum brakes at the back. Nowadays, many cars have disc brakes at both the front and rear. Because disc brakes have better heat dissipation than drum brakes, they are less likely to experience thermal fade during high-speed braking, thus providing better high-speed braking performance. However, when applying cold braking at low speeds, the braking effect is not as good as that of drum braking. The price is higher than that of drum brakes. So nowadays, many mid-to-high-end cars use full disc brakes, while ordinary cars use front disc brakes and rear drum brakes. However, relatively low-speed trucks and buses that require strong braking force still use drum brakes.

Under normal usage conditions, the front brake discs should be inspected every 60,000 kilometers and the rear brake discs every 120,000 kilometers. The maintenance cycles specified by different car manufacturers for various vehicle models are not exactly the same. The specific replacement cycle should be subject to the requirements of the car manufacturer.

There are three ways to determine whether brake discs need to be replaced:

1. Listen to the sound

If there is a "scraping against iron" sound or a loud noise when you gently press the brake (it could also be the effect of the brake pads being worn in when they are first installed), the brake pads must be replaced immediately at this time. Because the limit marks on both sides of the brake pads have directly rubbed against the brake disc, it proves that the brake pads have exceeded their limit.

When encountering such a situation, while replacing the brake pads, it is necessary to check the brake discs at the same time. When this kind of sound occurs, the brake discs are often damaged and have scratches. At this point, even if new brake pads are replaced, the noise still cannot be eliminated. It is recommended to replace the brake discs in a timely manner.

In addition, some low-quality brake pads have hard spots, which can also cause abnormal noises. Generally, such abnormal noises will disappear after being worn away for a period of time.

2. Check the brake disc warning light

Generally, whether the brake disc warning light on the dashboard is on or not is used as the basis for judging whether the brake disc should be replaced. Generally, this indicator light is off. When the brake disc malfunctions or is excessively worn, the light turns on and goes off after repair. When the warning light comes on, the brake discs have worn to their limit and the braking effect has declined, which greatly affects driving safety.

3. Check the thickness of the brake disc

Most brake disc products have wear indicators, which are three small pits distributed on the disc surface. The depth of the small pit measured with a vernier caliper is 1.5mm. That is to say, the total wear depth on both sides of the brake disc reaches 3mm. It is recommended to replace the brake disc in a timely manner.

If the thickness of the brake pads is low, they need to be replaced. The reason is:

1. As brake pads are consumables, they will gradually wear out during use. When they wear to the limit position, they must be replaced; otherwise, the braking effect will decline and even cause safety accidents.

2. Under normal driving conditions, brake pads should be inspected every 5,000 kilometers driven. Not only should the remaining thickness be checked, but also the wear condition of the brake pads should be inspected.

3. Also, check if the degree of wear on both sides is similar and if the return position is comfortable, etc. Any abnormal conditions found must be dealt with immediately.