Why it is important to check the thickness of motorcycle brake pads


Disc brakes are currently standard equipment for mainst […]

Disc brakes are currently standard equipment for mainstream motorcycles brake systems. The principle is to use the operating lever to squeeze the brake oil to push the piston to transfer the braking force. According to the caliper status, if you park your motorcycle for a long time, please be sure to check it before riding again.


Why is it important to check the thickness of the brake pads?


In the case where it has been stored for several years without riding, the front brake is stiff and stuck after holding the brake lever. The cause of the brake is not only the caliper sealing problem mentioned here, but also the brake pads of the caliper Caused by the problem of adhesion of the plug to the piston of the master cylinder.


As the brake shoe wears, the gap between the lever and the pedal increases as the brake shoe wears. This is because the parts in the brake drum do not automatically change position as the brake shoe wears, but the disc brake does not. As the brake pads wear, the tie rod or pedal clearance changes.


The reason is that as the brake pads wear out, the caliper piston will gradually push inwards towards the brake pads. If the brake pads wear out 1mm, the piston will push inwards by 1mm, and if it wears out 5mm, the piston will push forward by 5mm, Operated by the lever principle, the piston will protrude and push the brake pads to squeeze the disc.


So you don't need to adjust the clearance of the lever of the disc brake, but if you don't check the wear of the brake pads, you may find that the brake pads have been used up, causing the disc to be pressed by the metal bottom plate of the brake pads. Hmm... Because the metal bottom plate is a harder iron material than the disc, the surface of the disc will be scratched and the disc must be replaced.


Even if the tie rod clearance does not change, if the brake pads wear out and the caliper piston pushes out, the brake oil in the brake master cylinder oil pot will drop. Usually the oil pot has a liquid level check window, you can check the amount of liquid, so it is very important to check the amount of brake oil and the amount of remaining brake pads here.



Even if the brake pads wear out, the operation feel of the disc brake will not change.


The wear level of the brake pads can be seen from the oil level of the brake oil pot.


The remaining amount of brake pads can be measured directly with calipers.


Because the piston is sealed, the gap of the brake pads will not change


If the caliper piston is difficult to remove, be sure to push it out hydraulically before removing the brake hose. If the piston cannot be pushed out normally, soak it in hot water or heat it with a hot air gun to allow the brake fluid to be heated and softened.


In disc brakes, the caliper piston pushes inward as the brake pads wear, and the piston seal and dust seal play an important role. These are O-rings with a square cross-section, installed inside the caliper, while in close contact with the caliper piston.


When holding the brake lever, the fluid pressure of the brake fluid pushes the piston, and at the same time, the elastic piston seal pulls the piston in the extending direction. Then when the pull rod is released, the deformed seal will pull the piston back to complete the return work. This is the most important operation of the disc brake, called return.


The piston is pulled back by returning, but not mechanically returning, so if the brake pad wear exceeds the elastic deformation limit of the piston seal, the base point and starting position of the piston will change, and then the piston will protrude again. Then start back.


Through the elastic deformation of the piston seal, the disc brake does not need to be adjusted manually, the gap between the brake pad and the disc will not change, and the gap between the lever and the pedal will not change. The same applies to small-displacement motorcycles or single-piston calipers and six-piston calipers to large-displacement motorcycles.