Brake shoes, commonly known as brake pads, are consumables that gradually wear out during use. When they reach their maximum wear, they must be replaced, otherwise it will reduce the braking effect and even cause safety accidents. Brake shoes are related to life safety and must be treated with caution.
1. Under normal driving conditions, check the brake pads every 5000 kilometers, not only to check the remaining thickness, but also to check the wear status of the pads, whether the degree of wear on both sides is the same, and whether the return is smooth. If any abnormal situation is found, it must be dealt with immediately.
2. Brake shoes are generally composed of two parts: iron lining plate and friction material. Do not wait until the friction material part is worn out before replacing the shoes. For example, the front brake pads of Jetta (gallery forum) cars have a new thickness of 14 millimeters, while the maximum thickness for replacement is 7 millimeters, including a thickness of over 3 millimeters for the iron lining plate and nearly 4 millimeters for the friction material. Some vehicles are equipped with brake shoe warning function, and once the wear limit is reached, the instrument panel will sound an alarm prompt to replace the brake shoes. Shoes that have reached their limit of use must be replaced. Even if they can still be used for a period of time, it will reduce the braking effect and affect driving safety.
3. When replacing, it is necessary to replace the brake pads provided by the original spare parts. Only in this way can the braking effect between the brake pads and brake discs be the best and wear be minimized.
4. When replacing the brake pads, a special tool must be used to push the brake cylinder back. Do not use other pry bars to forcefully press back, as this can easily cause the brake caliper guide screw to bend and cause the brake pads to get stuck.
5. After replacement, be sure to step on the brake pedal a few times to eliminate the gap between the shoe and the brake disc, which may cause the first foot to not brake and lead to accidents.
6. After replacing the brake shoes, they need to be run in for 200 kilometers to achieve the best braking effect. The newly replaced shoes should be driven with caution.

The force exerted by the brake caliper piston on the brake pads is called the Pedal Force. The force exerted by the driver on the brake pedal is amplified by the lever of the pedal mechanism, and then amplified by the vacuum power boost using the principle of vacuum pressure difference to push the brake master cylinder. The hydraulic pressure emitted by the brake master cylinder utilizes the incompressible power transmission effect of the liquid, which is transmitted to each cylinder through the brake oil pipe. The pressure is amplified using the "Pascal principle" to push the piston of the cylinder to apply force to the brake pads. Pascal's Law refers to the principle that the pressure of a liquid at any position inside a closed container is the same.
Pressure is obtained by dividing the applied force by the area under force. When the pressure is equal, we can achieve the effect of power amplification by changing the ratio of the applied and applied force areas (P1=F1/A1=F2/A2=P2). When used in brake systems, the ratio of master cylinder to slave cylinder pressure is the ratio of master cylinder piston area to slave cylinder piston area.