After changing the brake pads, why do you have to step on the brakes?
Many people replace the brake pads by themselves. In addition to the correct installation of the brake pads, do not install them upside down. After replacing the brake pads, the most important operation should be to step on the brakes in situ. This operation is often forgotten, even in 4S stores and maintenance shops, sometimes after replacing the brake pads. If you drive away without stepping on the brake, the final result will basically be a collision, because you have just replaced the brake pads, and there is no brake on the front two feet. When driving at low speed, I usually step on the brake when I am very close to an obstacle. I feel that the brake pedal is very light when I step on it. There is no brake. Most people will panic and will not step on it continuously, which will eventually lead to an accident. Today can be regarded as a reminder that all car owners who change brake pads should pay attention to it.
Why are there no brakes on both feet before changing the brake pads? Let me elaborate on this question. The most fundamental reason is that the brake pad is too far from the brake disc. When I stepped on the brake, although the brake pad moved forward to clamp the brake disc, the distance moved forward was not enough to contact the brake disc, and friction could not be generated between them to brake. Why is the new brake pad too far from the brake disc? This is the need for installation, otherwise the new brake pad cannot be installed smoothly.
The normal brake pads and brake discs are always close together, so that the piston moves outward a little to brake. As the brake pads become thinner and thinner, the piston of the slave cylinder will gradually move outward. If it does not move outward, the brake pads cannot be close to the brake disc. The thickness of the new brake pad is very thick. Before installation, the piston of the brake cylinder needs to be fully pushed back, that is, the piston is fully retracted into the cylinder, so that there is enough space for installing the new brake pad. If the piston does not retract, it will be blocked by the piston when installing the brake pad, and it is impossible to install it at all. Because the piston is fully retracted, the distance between the piston and the brake disc is far. Even if a thick new disc is installed, if the new disc is next to the piston, the new disc will not be able to touch the brake disc. The piston needs to move outward for a long distance to contact the brake disc against the brake pad.
It is because the piston is fully retracted and the brake pad is far from the brake disc that the front two feet are not braked. When stepping on the brake, the master cylinder piston pushes the brake oil forward, and the brake oil then pushes the slave cylinder piston forward. However, with one foot on the brake, the distance between the master cylinder and the slave cylinder is not long. Although the piston of the slave cylinder moves outward, it cannot reach the brake disc once because of its long distance from the brake disc. You need to release the brake and step on it again, and then move outward a little distance to reach the brake disc. As long as the piston abuts the brake pad and the brake disc closely together, the brake can return to normal. Therefore, it is generally necessary to step on the two foot brake and move the cylinder piston outward twice
Don't forget to step on the brake pads when you change them yourself. Ordinary maintenance technicians will help step on them when you change them at the 4S store or repair shop. However, if you watch at the scene, they will let you directly drive out of the workshop after the replacement. The maintenance technicians may also forget to step on them. At this time, don't forget to step on them. Whenever you feel that the brake doesn't work, don't give up the brake. It's better to step on it continuously. When driving at a low speed, the hand brake is the best brake auxiliary component. Without the brake, you can consider using the hand brake to brake. Don't forget.