Checking the remaining brake pads is the first step for a brake maintenance. In the case of the disc brake system, the play of the lever or pedal does not change unlike the drum brake system even if the brake pads are worn, so it is important to visually check the brake pads directly. It is better to check the brake disc at that time. The brake disc may be damaged more than expected, depending on the compatibility with the brake pads material and the usage environment, so be careful for it.
Table of Contents
- 1. In a disc brake system, not only the brake pads are worn but also the brake disc.
- 2. The degree of wear of the brake disc may vary depending on the material of the brake pads.
- 3. Check the unevenness of the brake disc surface with a metal ruler.
- 4. Let's check not only the brake pads but also the wear of the brake disc when performing a regular check of the brake system.
1. In a disc brake system, not only the brake pads are worn but also the brake disc.
When the brake pads wear to about half the thickness compared to the time when it is new, the wear speed of the brake pads is faster. If sandwiching the brake disc only with the back plate of the brake pad, after all the friction material of the brake pads is gone, not only the brake system will not work properly, but also the brake disc is abnormally worn and becomes unusable, so it is necessary to pay attention to the wearing of the brake pads.
Regular maintenance of caliper piston and replacement of brake fluid are very important for the brake system so that the same brake work and brake touch can be obtained at any time regardless of the season and weather.
If you are cautiously paying attention to the brake, you can avoid the worst-case scenario of the "iron plate brake" where the brake disc is pinched by the back plate. The wearing speed of the brake pads is different when they are new and somewhat reduced.
If the friction material of the brake pads pasted to the back plate became thinner, the volume of the friction material and the heat receiving capacity decreases, and the heat radiation also reduces, resulting in wear of friction material. In other words, the wearing speed of the brake pads increases after wearing out a certain amount.
If you miss and neglect to check the remaining wear amount of the brake pads thinking that, "Since it's still about half of the remaining thickness compared to a new one, it can be used on the same distance", the brake pads will be the minimum wearing thickness with unexpected speed, or the wear of the pads may be known for the first time by the sound of the metal that sandwiches the brake disc with the back plate.
It is better to check the wear amount of the brake pads at the same time while checking the wear amount of the brake disc. The brake disc is made of materials such as stainless steel, cast iron, and carbon. In the commercial motorcycle, stainless steel brake discs are used, which do not rust in rainy weather and provide braking power even at low temperatures.
Considering the relationship between brake pads and brake disc, many riders or mechanics think that the only thing that will be reduced is the brake pads, and the brake disc can be used for a long time. However, in reality, the brake disc will also be worn out just like the brake pads.
2. The degree of wear of the brake disc may vary depending on the material of the brake pads.
The aggression against the brake disc depends on the material of the brake pads. In general, organic brake pads that is baked and hardened plastic components is less aggressive to the brake disc, and the sintered brake pads using sintered metal has better-stopping power, but it will wear the brake disc more than organic brake pads.
The two major factors of brake disc wear are: 1. Compatibility with the brake pads, 2. It depends largely on the usage environment.
The compatibility is related to the material of the brake pads. The sintered brake pads used metal for the material is more strong stopping power than the organic brake pads using plastic material, but the damage to the brake disc is bigger.
Besides, gravel and dirt are splashed together with rainwater on the brake disc, and brake caliper sandwich the brake discs together with gravel and dirt, so riding a motorcycle in the rainy weather is more vulnerable to damage than riding a motorcycle in the fine weather. If the brake pads and brake disc are worn at the same time, the shape of the unevenness on both worn out surfaces will match.
However, since the new brake pads have a smooth surface and less area in contact with the worn brake disc, it cannot be obtained sufficient stopping power. Furthermore, in the case of some aftermarket brake pads, since the shape of the friction material is slightly different from OEM brake pads and the contact area with the brake disc cannot be sufficiently secured, the stopping power may be lesser.
Just like when the brake pads are worn, the worn brake disc accumulates braking heat because of reduced heat dissipation efficiency, which can cause cracks in the case of deformation or perforated brake disc. For this reason, many brake disc surfaces are engraved with the thickness of the wear limit indicating the service limit, and if the thickness of the brake disc, measured with a caliper or micrometer, is less than to that, replace the brake disc.
3. Check the unevenness of the brake disc surface with a metal ruler.
To determine the actual life of the brake disc, the thickness of the area where the brake pads are in contact is important instead of the thickness of the outer edge. Place a metal ruler from the center of the brake disc to the outer circumference, and check the unevenness of the contact surface of the brake pads. Measure the number of dents on the front and back, replace the brake disc if the wear limit has been reached.
However, depending on the contact position between the brake pads and the brake disc, there is a case where the thickness of the outer peripheral portion is less than the wear limit, the inner portion may be largely reduced. Furthermore, since the surface of the brake disc is sometimes worn in a wavy shape, it is better to check the brake disc with putting a metal ruler on the brake disc unless you are sure by looking at your eyes.
In the case that the brake disc has small scratches like a record disc, it is understandable that the motorcycle continued to run in the state where gravel was sandwiched between the brake pads and the brake disc, such as in rainy weather. The perforated brake disc has a hole to improve the draining properties of the brake disc surface, which is effective for braking in rainy weather, and it is better to wash the dirt of the brake disc to avoid scratching after riding especially on rainy season.
Also, if it is a piece of solid brake disc instead of a floating type of brake disc, it may be possible to flatten the unevenness of the surface by polishing with an internal combustion engine shop, so it is better to consult a professional mechanics.
4. Let's check not only the brake pads but also the wear of the brake disc when performing a regular check of the brake system.
If the brake pads wear, the brake discs also wear. Make your choice based on how you use your motorcycle and your braking preferences, whether to allow the aggression to the brake disc by giving priority the goodness of the brake performance or using brake pads that take into account its life span.
