How to maintain the motorcycle? Can it be easy to use and have a long service life?

The characteristic of disc brake is that after the rider's hand leaves the brake lever, the brake pad will open automatically. However, if you want to make the brake pads work smoothly, the maintenance of the brake calipers must be done. If the action of the brake caliper piston of the double piston and the opposite four piston is not synchronous, the piston cleaner can be used to solve it.

 

If the piston is dirty, it is difficult to return = to make it easy for the disc to stick to the disc all the time

 

When disassembling the vehicle body and pulling out the piston of the brake caliper, if the piston cannot be removed smoothly by using the piston caliper and the gas in the air compressor, the brake oil pipe can be directly connected to the brake master cylinder and pushed out by tap water.

 

It's a bit wasteful to use brake oil just by removing a piston, and there's no need to worry about the damage caused by dirt when using tap water. After use, remember to wait until the water in the brake master cylinder and oil pipe is completely dry before reinstalling it.

 

When your hand leaves the brake lever, the piston pushed into the brake master cylinder will return to its original position through the return spring, and the brake oil pushed to the side of the brake caliper by the brake oil pipe will return to the oil pot of the brake master cylinder. At this time, the pressure on the brake oil inside the brake caliper will also disappear. When the brake oil returns to the brake master cylinder, the piston pressing the brake pad will also return to the brake caliper. When the brake disc is clamped to reduce the force applied to the brake disc, the braking force will disappear automatically.

 

Even if you don't notice these when riding, these parts will act independently whenever you release or hold the brake lever. If the hydraulic disc system is used, the most important in this series of actions is the roll back of the caliper oil seal. When the oil seal turns back, it can restore the deformed oil seal to its original shape, and the oil seal connecting the brake caliper piston can not only prevent the leakage of brake oil inside the brake caliper, but also return the advancing piston to its original position.

 

When the increased gap between the brake pad and the brake disc exceeds the deformation range of the oil seal, the piston will move forward automatically to keep the distance between the brake pad and the brake disc at an appropriate value, which is the characteristic of the disc brake system. Because of this feature, the motorcycle with disc brake does not need to adjust the clearance like drum brake.

 

Since the moving range between the separated brake pads and the brake disc is only a little distance, the unit of travel of the brake caliper is usually only a few millimeters. Theoretically, if the wheel hub and the brake disc are not skewed, the gap between the brake disc and the brake disc will not exceed 0.1mm, so the piston stroke of the floating caliper will start braking as long as it moves 0.2mm. On the contrary, if the piston returns to the inside of the caliper within 0.2mm after releasing the brake lever by hand, the brake pad should leave the brake disc.

 

However, in real life, it may not change according to the above description. It is usually necessary to pay attention to whether the piston does not move smoothly because it is dirty, or whether the disc has been leaning against the disc. The ideal state is to brake in an ultra short piston stroke, but if you want to keep the piston homing normal all the time, even if the roll back distance of the caliper oil seal is very small, the piston must be able to change according to the knight's operation. To achieve this, it becomes very important whether the surface of the brake caliper is smooth. It should be fully lubricated during normal maintenance.

 

If a lot of dust or dust is accumulated on the piston surface to wear off the disc, the oil on the piston and caliper oil seal will deteriorate or dry, and finally the piston will not be able to return to its original position smoothly. It's easy to find that the brake is too sensitive, but it's generally difficult to detect if the brake pad is stuck to the brake disc all the time without making any sound.

 

Take the car with floating calipers as an example. If the tire is off the ground and the engine idles, and the idling stops immediately, you can press the calipers first, forcibly open the brake to make the distance between the disc and the disc, and then try to let the engine idle. If the friction becomes smaller and the idling time becomes longer at this time, it is likely that it is because the disc is always close to the disc. To be on the safe side, you can try braking again and then let it idle. If you think the tire is very heavy, you can be sure it's because you want to keep the disc on the disc all the time.

 

By using the adjuster flexibly, we can see whether the piston actuation is synchronous

 

Install the disc brake adjuster and hold the brake rod, you can find that the piston on one side does not come out at all. Because the piston is too dirty, the correct way is to pull it out directly rather than push it back into the caliper. When replacing the worn brake lining, if you don't think too much and press the piston directly back into the caliper, even if you replace the brand-new lining, there is likely to be a problem of asynchronous piston actuation. If you use a split wrench instead of the disc brake adjuster, you can clamp the piston at the position where it is quickly pulled out of the brake caliper. The thickness of the wrench used for fixing depends on the length of the brake caliper and piston. Please adjust it according to the actual situation. Although the piston is very dirty, fortunately, the hard chromium plating on the piston surface is not rusty.

 

The dirty piston of the brake caliper will not only cause the brake pad to be unable to return smoothly, but also affect the smoothness of the action of the brake pad. Pascal principle is applied to the pistons of one-way double piston and opposite four piston brake caliper. Because the same pressure will be generated on the brake oil, as long as the brake pull rod is pressed, the stroke of all pistons should be the same. However, when the brake pad is removed and the piston actuation of the dirty brake caliper is observed, it can often be seen that the actuation between the pistons is not synchronized.

 

Of course, in the actual brake (install the brake to make the pad clamp the disc), because the pressure applied to the piston will increase, even if the piston does not move synchronously, it can still push to make the pad move. However, the piston with little friction loss between the piston and the oil seal can operate smoothly without making the plate and less burden. On the contrary, the piston with large friction loss will be difficult to leave the inside of the brake caliper.

 

This time, let's not discuss whether we can actually detect this difference. If the piston is pressed to actuate the unsynchronized braking system, the piston with faster moving speed will first contact the arrival plate and push the arrival plate to the disc, while the piston with greater friction loss will start pushing the arrival plate to move after that. Conversely, when you release the brake lever, although the piston with less friction loss will return to its original position, you may not wait for the piston with poor actuation to leave to make the brake pad.

 

The disc brake adjuster used when replacing the brake pad can help us easily observe how the piston actually works. Insert the adjuster into the brake caliper where the piston returns, open the brake pad to the preset width, and then press the brake pull rod, you can actually see how the piston on the other side acts after the piston with faster actuating speed reaches the position of the adjuster one step first.

 

It may be trying to catch up with the piston that has been actuated first, or it may stop halfway, or the piston on the other side finally starts to operate after the piston that has been actuated first has touched the regulator. Different brake calipers have different movement modes of asynchronous pistons, but their common point is that as long as the piston is dirty, it will have a great impact on the actuating speed.

 

Even if the film is not worn out, even if the piston of the brake caliper does not look very dirty, if you push the piston out of the caliper, use neutral detergent or part cleaning agent, and then apply a thin layer of silicone spray, what you can do is to reduce the friction loss when you push the piston back to the caliper. After you install the brake system back, just push the motorcycle and you will find that the whole car has become lighter.

 

Even if the brake pads are worn, the clearance between the pull rod and pedal of the disc brake system will not change much, so people often don't know when to go for maintenance. However, as long as the piston surface of the brake caliper becomes very dirty, even if the brake pad can still be used, it is recommended that you maintain the piston.

 

If the piston is removed from the brake caliper, be sure to replace the oil seal

 

Sometimes the cleaning effect may not be enough by relying on toothbrush and brake disc cleaner alone, so you can first remove the piston, coat it with a little chemical specially used to grind metal, and then wipe off the dirt with a car cleaning cloth. Can piston oil seals and dustproof oil seals be lubricated with silicone spray? For this problem, it is recommended that piston oil seal use brake oil and dust-proof oil seal before using silicone spray. Be sure not to use mineral containing lubricating spray, otherwise it may cause the oil seal to expand.

 

Not only is the piston very dirty, but also the oil seal on the brake caliper is in bad condition. The dust-proof oil seal on the right side has expanded and the whole oil seal runs out of the oil seal groove. It is admirable if the braking system can work normally in this state. Grinding the piston a little and replacing the oil seal can solve the problem of poor braking and make the response more sensitive.

 

If the dirt on the piston surface can be removed at once, the operation will be very easy. Suppose that the brake pad is worn and the oil seal runs out. If the piston is still very dirty, it is better to pull the piston out of the brake caliper and grind it a little.

 

Compared with cleaning while rotating with tools, it is easier to directly clean the dirt on the piston with a special agent for metal grinding, and it can be thoroughly cleaned to every corner. However, it is sometimes difficult to clean the piston completely because the dust seal of the brake caliper should not be removed while cleaning.

 

However, if you directly remove the piston from the caliper, you don't need to be careful with the piston oil seal and dust seal. According to the instructions in the owner's manual, when the piston is removed from the brake caliper, the piston oil seal and dust seal must be replaced with new ones. Some models even specify the replacement frequency.

 

If you only need to maintain the brake caliper piston, considering the CP value, do not remove the piston during cleaning, so you can save the cost of replacing the oil seal. If the piston is very dirty and a pile of brake oil crystals have accumulated outside the dust-proof oil seal, directly pull out the piston, replace it with a new oil seal, and clean the dirt in the oil seal groove of the brake caliper, so as to restore the braking function.

 

The effect of cleaning the brake caliper piston is absolutely beyond your imagination. Just because the piston can move smoothly, the starting of the motorcycle can become much lighter. In addition to the knights who pay attention to the chassis system, this maintenance work is also highly recommended for knights who like street driving and long-distance travel.