What about partial wear of brake pads?
To put it directly, the process is like this: after we step on the brake pedal, the force on the brake pedal is amplified by the vacuum booster pump and transmitted to the brake master cylinder. The brake master cylinder transmits the liquid pressure of the brake oil to the piston of the brake slave cylinder at each wheel position. Under the effect of the liquid pressure, the piston extends and compresses the brake pad to the brake disc, and the gap between the brake pad and the brake disc Friction causes the speed of the brake disc to decrease, and then the speed will decrease until it stops.
After stepping on the brake, the brake pad always needs to rub against the brake disc, so the thickness of the brake pad and the brake disc will become thinner due to friction, which cannot be avoided. And the thickness of the brake pad thins quickly. When it is worn to the specified thickness, we need to replace it in time. There is no mileage regulation for the replacement of brake pads, because it has a lot to do with the driving habits of car owners.
This is a little basic knowledge about the brake. Let's look at this Toyota overbearing. Its brake pads have reached the required replacement thickness and need to be replaced. However, the master found that there is a big gap between the thickness of the brake pads on both sides of the brake disc, that is to say, the brake pads have eccentric wear. As shown by the arrow in the figure below, the thickness difference between the left and the right is very large.
Under normal circumstances, the thickness of these two brake pads should be similar, but now the thickness gap is so big, what's the problem? Let's take a look at the basic knowledge of brake caliper.
There are two types of brake caliper for disc brake, one is fixed brake caliper, the other is floating brake caliper. The most common type is floating brake caliper, which is composed of bracket and caliper body. The bracket is fixed on the steering knuckle, and the caliper body is connected to the bracket through the guide pin, which can move on the guide pin.
The domineering brake caliper is fixed, that is to say, its brake caliper is generally fixed on the steering knuckle, the caliper body will not move during the braking process, and the two pistons on both sides of the brake disc move and pressure the brake pads, as shown by the green arrow and orange arrow in the figure below, with two pistons on each side
Let's take a look at the floating brake caliper, as shown in the figure below. This is a Citroen brake caliper. The green area shows the guide pin. The upper part on the left side of the guide pin is the brake caliper bracket, which is installed on the steering knuckle, and the right side of the guide pin is the brake cylinder.
When you step on the brake, the bracket won't move, and the caliper will move, giving pressure to the brake pads on both sides of the brake disc. The arrow shows the installation position of the brake oil pipe on the wheel cylinder. Only this side has a piston. If this kind of brake caliper has the problem of eccentric wear of brake pad, it may be caused by the corrosion of guide pin and piston, but the possibility is very small
This domineering is a fixed brake caliper. The most likely reason for the eccentric wear of its brake pads is that the piston inside the caliper body is corroded. The reason for the corrosion is that the brake oil has not been changed for a long time, resulting in excessive water content in the brake oil, and then the piston is corroded and stuck. There is only one solution at this time, that is to replace the brake caliper assembly.
After the overlord owner understands the situation, he directly agrees to replace a new brake caliper, as shown in the figure below. This is the new brake caliper assembly.
As shown in the figure below, the new and old brake calipers are compared. As shown in the green area, these two positions are where the brake caliper is fixed on the steering knuckle.
As shown in the figure below, the new brake caliper assembly has been installed and the brake oil pipe has been connected.
As shown in the figure below, the old and new brake pads are compared. After the new brake pads are installed, another operation that must be carried out is to replace the brake oil and exhaust the air. The master replaced the brake oil with a professional instrument, and it was quickly replaced.
After the brake oil is changed, the master has to carry out a road test to test it. This is the process of master repairing the partial wear of overbearing brake pads. The main reason is that the brake oil has never been changed. This also gives us a reminder that we should change the brake oil according to the regulations and check the wear of the brake pads, so as to solve the problems in time.