Brake shoes, commonly known as brake pads, are consumable items. They gradually wear out during use. When they are worn to the limit position, they must be replaced; otherwise, the braking effect will be reduced, and even safety accidents may occur.
Brake shoesare closely related to life safety and must be treated with great caution.
Most cars adopt a front-disc and rear-drum brake structure. Generally speaking, the frontbrake shoeswear out relatively quickly, while the rear brake shoes last longer. In daily inspection and maintenance, the following aspects should be focused on:
Under normal driving conditions, check the brake shoes every 5,000 kilometers. Not only should you check the remaining thickness, but also the wear state of the shoes, whether the degree of wear on both sides is the same, and whether they can return to their original positions freely. Any abnormal situations must be dealt with immediately.
As vehicles have become more complex and high-tech, modern inspection techniques have also advanced significantly. Näiteks, in addition to the traditional visual and manual checks, some high-end cars are now equipped with intelligent sensors that can continuously monitor the wear of brake shoes. These sensors can precisely measure the thickness of the friction material and the overall condition of the shoes in real-time, sending alerts to the driver’s dashboard or even directly to a connected mobile app long before a potential issue becomes critical. Moreover, with the development of vehicle-to-everything (V2X) communication technology, this wear data could potentially be shared with maintenance facilities, allowing for proactive service scheduling.
Brake shoes usually consist of an iron backing plate and friction material. Do not wait until the friction material is completely worn out before replacing the shoes. Näiteks, the front brake shoes of a Jetta, the new ones have a thickness of 14 mm, and the replacement limit thickness is 7 mm, which includes a more than 3-mm iron backing plate thickness and nearly 4-mm friction material thickness. Some vehicles have a brake shoe warning function. Once the wear limit is reached, the instrument panel will give an alarm to prompt for replacement. Brake shoes that have reached their service limit must be replaced. Even if they can still be used for a while, they will reduce the braking effect and affect driving safety.
The development of new friction materials is also an area of continuous research. Traditional semi-metallic friction materials are being gradually replaced by more advanced ceramic and carbon fiber composites. These new materials offer better heat dissipation, less noise during braking, and longer service lives. Siiski, they also require more precise matching with brake discs. Manufacturers are constantly running tests to optimize the combination of these new materials and existing braking systems, aiming to further improve braking performance while reducing wear.
When replacing, use the brake pads provided by the original factory spare parts. Only in this way can the best braking effect and the least wear between the brake pads and the brake discs be achieved.
In the aftermarket, there is a wide variety of brake pads available, but not all of them meet the strict quality standards of original equipment manufacturers (OEMs). Non-genuine pads may seem cost-effective initially, but they often have inconsistent friction coefficients, which can lead to uneven braking force distribution. This can cause the vehicle to pull to one side during braking, posing a serious safety hazard. To ensure the integrity of the braking system, strict quality control measures are implemented by OEMs, from the selection of raw materials to the final assembly of the brake pads.
When replacing the shoes, a special tool must be used to push the brake caliper piston back. Do not use other pry bars to force it back, as this can easily cause the brake caliper guide screws to bend and the brake pads to get stuck.
The proper use of tools in automotive maintenance cannot be overstated. With the increasing complexity of braking systems, especially in electric and hybrid vehicles with regenerative braking functions, the brake calipers and pistons have become more delicate. Specialized tools are designed to apply the correct amount of force evenly, protecting the internal components from damage. In addition, improper use of tools can also disrupt the precise alignment of the brake pads within the caliper, affecting the overall braking performance.
After replacement, be sure to step on the brake pedal several times to eliminate the gap between the shoes and the brake disc. Otherwise, there may be no braking effect on the first pedal press, which can easily lead to an accident.
This step is crucial in the post-replacement process. In modern braking systems, the clearance between the brake pads and the disc is carefully calibrated to ensure optimal performance. When new pads are installed, this clearance needs to be readjusted. By stepping on the brake pedal, the hydraulic system activates, pushing the pads closer to the disc until the proper working clearance is achieved. This process also helps to seat the pads evenly against the disc surface, ensuring consistent friction across the entire contact area.
After replacing the brake shoes, they need to be run in for 200 kilometers to achieve the best braking effect. Be cautious when driving with newly replaced shoes.
The break-in period for brake shoes is essential for their long-term performance. During the initial 200 kilometers, the friction material on the new pads gradually conforms to the surface of the brake disc. This process is like a gentle polishing, creating a more uniform contact surface. If the vehicle is driven too aggressively during this period, uneven wear may occur, shortening the lifespan of the pads and potentially reducing the braking efficiency. As vehicles are now often equipped with advanced driver assistance systems (ADAS), it’s important that the proper braking performance is achieved during this break-in phase to ensure the seamless operation of these safety features.
As the automotive industry moves towards more sustainable and intelligent transportation, braking systems are evolving accordingly. Electric vehicles, for example, rely not only on traditional mechanical braking but also on regenerative braking, which converts kinetic energy into electrical energy during deceleration. This dual braking mechanism places new demands on brake shoes. They need to work in harmony with the regenerative system, smoothly transitioning between the two braking modes. Maintenance procedures for such hybrid braking systems are more complex, involving not only the inspection of physical components like brake shoes but also the calibration of electronic control units that manage the energy recovery process.
Another emerging trend is the integration of autonomous driving technology. Self-driving cars require extremely reliable braking systems. Brake shoes in these vehicles need to be monitored even more closely, with real-time data analysis to predict potential failures long before they occur. This means that maintenance intervals may need to be adjusted, and more sophisticated diagnostic tools will be needed to keep these highly automated vehicles safe on the road.
In addition, environmental regulations are becoming stricter, pushing manufacturers to develop more environmentally friendly brake shoe materials. These materials should not only meet strict emission standards during production but also be more recyclable at the end of their service lives. Research is underway to find new compounds that can reduce the generation of harmful dust particles during braking, improving air quality, especially in urban areas where traffic congestion leads to frequent braking.
