[百問]8 Questions about Brake Modification Compulsory Courses (Part 2)

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Question 7. What is a multi-piston caliper?

For the single-piston calipers of many RVs, the contact area between the disc and the disc will have a useless area that cannot be filled. In order to increase the friction area, the volume of the caliper body is reduced and the piston area is increased. The maximum amount, so there will be the emergence of multi-piston calipers. This kind of fixed opposed multi-piston clamp has the advantages of good overall rigidity, strong clamping force, average force and quick response. The body made of aluminum alloy material can also provide better than the original factory. The light weight and heat dissipation effect of the cast iron material can effectively reduce the weight of the large-size disc set and reduce the working temperature of the brake fluid. The brake system naturally provides a more stable braking effect, so there are so many performance cars equipped with multiple pistons Calipers.

The number of pistons in a multi-piston caliper is not equal to the strength of the braking force, because the pistons are round. If the caliper body is small but equipped with too many pistons, it may not be conducive to the increase of the braking force. The number of pistons still depends on the caliper. The proper size of the body is better. Generally speaking, if you have a 17-inch wheel frame, you can configure a four-piston caliper or a small six-piston caliper; an 18-inch and a 19-inch large four-piston caliper or a six-piston caliper; and an eight-piston caliper for a 20-inch or more.

When replacing a multi-piston caliper, remember to ask the store to drain the air inside the brake fluid. Because the internal oil passage of this part is more complicated, the air discharge procedure is relatively troublesome. There are two air discharge screws inside and outside, remember two The screws must face upwards, and both must be loosened to open the air, and the more piston calipers, the more attention should be paid to this problem. After installation, it is best to perform a road test and confirm that there is no problem before it is completed.

In addition, it is the manufacturing precision of the brake caliper adapter. The adapter with accurate size and angle should make the wheel cylinder and the disc completely parallel, so that when the wheel cylinder pushes the brake pads, the force can be applied to the disc without angular deviation. Reduce the control that is conducive to the stroke, so that you can have a good brake pedaling feeling.

Question 8. What is a ceramic brake disc?

The so-called "ceramic disc", in addition to "ceramic", also includes carbon and carbon fiber in the cost, so the common English title is Carbon Ceramic, and it needs to be used with a special brake to make the film. When the disc is made of carbon fiber silicon carbide composite material, the heat resistance limit of the disc can be increased. Taking the F1 racing car as an example, it can withstand temperatures above 1000°C, and the instantaneous temperature resistance can even reach 1200°C. The high temperature and the heat dissipation speed of this kind of disc is faster than steel, so it is very suitable for racing, but its best working temperature is between 300°C and 800°C, and the braking reaction will be less than 300°C. It is very poor, not suitable for road use, and will accelerate oxidation when it exceeds 800°C, and its service life cannot be as durable as traditional steel plates.

Ceramic discs were later extended to be used in high-performance supercars. However, under different manufacturing processes, the functions and effects of ceramic discs used in commercial cars are very different from those used in racing cars. Generally speaking, in addition to the advantages of ceramic discs on commercially available cars, besides the same light weight effect, the service life is its purpose. Normal use can have more than four times the mileage of traditional discs, but if you plan to In the case of intense driving in the racetrack, it may be expected that the life of the ceramic disc will be greatly reduced.

According to some car owners, the life of the ceramic disc is only 2000-3000 km in extreme track usage situations. This is because when the temperature of the ceramic disc continues to exceed 600°C, the internal carbon content will begin to turn into carbon dioxide. , And become lighter. After a certain level of lightness, the disc can no longer be used. Therefore, if you plan to drive intensely on the track, it is best to replace the expensive ceramic brake to effectively continue the ceramic brake disc. Life.