Currently, the brake system of most of the domestic cars on the market is divided into two types: disc brakes and drum brakes. Disc brakes, also called “disc brakes”, are mainly composed of brake discs and brake calipers. When the wheels are working, the brake discs rotate with the wheels, and when the brakes are working, the brake calipers push the brake pads to rub against the brake discs to produce braking. Drum brakes are made up of two bowls combined into a brake drum, with brake pads and return springs built into the drum. When braking, the expansion of the brake pads inside the drum and the friction generated by the drum achieve the effect of deceleration and braking.
Brake pads and brake discs are two very important components of a car’s braking system, and it can be said that their normal operation is a matter of the life and safety of the passengers in the car. Today we will teach you to judge the thickness of the brake pads to determine whether the brake pads should be replaced.
How to judge whether the brake pads should be changed
We often hear people say that brake pads generally need to be replaced at 50,000-60,000 kilometers, and some even say that they should be replaced at 100,000 kilometers, but in fact, these statements are not strict enough. We just need to think with our brains to understand that there is no exact number of brake pad replacement cycles, different driver habits will definitely make a huge difference in the wear and tear of brake pads, and the replacement cycle of brake pads for vehicles that have been driving on city roads for a long time is significantly shorter than that of vehicles that have been driving on the highway for a long time. So, when exactly do you need to replace the brake pads? I’ve listed a few ways you can test them yourself.
Judging the thickness of the brake pads
1、Look at the thickness to determine whether the brake pads should be replaced
For most disc brakes, we can observe the thickness of the brake pads with the naked eye. In long-term use, the thickness of brake pads will become thinner and thinner as they keep rubbing during braking.
A brand-new brake pad is usually about 37.5px thick. If we find that the thickness of the brake pad is only about 1/3 of the original thickness (about 12.5px), we need to observe the thickness change frequently.
When there is about 7.5px left, it is time to replace them (you can ask a technician to measure them with calipers during maintenance).
The service life of brake pads is generally around 40,000-60,000 kilometers, and the harsh car environment and aggressive driving style will also shorten its service life in advance. Of course, individual models cannot see the brake pads with the naked eye due to the design of the wheel or brake caliper (drum brakes cannot see the brake pads due to the structure), so we can have the maintenance master remove the wheel to check the brake pads during each maintenance.
Judging the thickness of brake pads
There is a raised mark on both ends of the brake pads, about 2-3 mm thick, which is the thinnest replacement limit of the brake pads. If you find that the thickness of the brake pads is almost parallel to this mark, you need to replace the brake pads immediately. If not replaced in time, when the brake pad’s thickness is lower than this mark, it will seriously wear the brake disc. (This method requires removing the tire for observation, otherwise it is difficult to observe with the naked eye. We can have the operator remove the tires during maintenance and then check.)
2、Listen to the sound to determine whether the brake pads should be replaced
For drum brakes and individual disc brakes, which cannot be seen with the naked eye, we can also use sound to determine whether the brake pads have been worn thin.
When you tap the brake, if you hear a sharp and harsh sound, it means that the thickness of the brake pad has been worn below the limit mark on both sides, causing the mark on both sides to rub the brake disc directly. At this point, the brake pads must be replaced immediately, and the brake discs must also be carefully inspected, as they are often damaged at this point. (It should be noted that if the brake pedal has a “bare” sound as soon as you step on it, you can basically tell that the brake pads are thin and need to be replaced immediately; if the brake pedal is stepped on until the second half of the journey, it is likely that the brake pads or brake discs are caused by problems in workmanship or installation, and need to be checked separately.)
When braking, the constant friction between brake pads and brake discs will also cause the thickness of brake discs to become thinner and thinner.
The life span of front and rear brake discs varies depending on the type of vehicle being driven. For example, the life cycle of the front disc is about 60,000-80,000 km, and the rear disc is about 100,000 km. Of course, this is also closely related to our driving habits and driving style.
3. The strength of the brake feeling.
If the brakes feel very hard, it is possible that the brake pads have basically lost their friction, which must be replaced at this time, otherwise, it will cause serious accidents.
4、Analysis according to the braking distance
To put it simply, the braking distance of 100 km per hour is about 40 meters, 38 meters to 42 meters! The more you exceed the brake distance, the worse it is! The farther the braking distance is, the worse the braking effect of the brake pad is.
5、Step on the brakes to run off the situation
This is a very special case, which may be caused by the different degrees of brake pad wear, and if all the brake pads are judged to be inconsistent with the degree of brake pad wear, then they should be replaced.
Post time: Dec-28-2022