AP Racing calipers explain - the most comprehensive analysis of history (on)!

 AP Racing, as the world's leading brake modification brand, is the most popular brake brand in China. Wide range of applications, various models, high cost performance, and so on, all sorts of factors have led to it becoming the best brand of brake in the Chinese market. Today we will give you a brief introduction to the basics of AP Racing's street calipers, which will help you learn more about what brakes we have purchased and buy them with confidence:

one. AP Racing naming method:

CP5785-2S0MPD

"CP5785" stands for the total caliper series number. For example CP5200, CP8530 and so on.

"2" represents the left and right positions of the caliper, the even number is the right hand side, and the odd number is the left hand side. For example, CP8540-8S0R2 means that the 8540 caliper should be installed on the right hand side, and CP8520-9S0R2 means that this caliper should be on the left hand side.

"S" stands for the position of the oil inlet, with the letter "E", S for the oil inlet on the side, and E for the oil inlet on the tail. For example, the CP8520-2S0R2 indicates that the oil inlet is on the side of the CP8520 caliper.

"0" represents the pound number of the caliper piston return spring, and the number "4" "7" "9", 0 represents the piston does not return the spring, 4,7,9 represents the caliper with the return spring is 4 pounds , 7 pounds, 9 pounds, the higher the pounds, the stronger the ability of the piston to return, the faster the caliper responds.

 “M” stands for the material of the piston. If there is no letter in this position, the piston material is aluminum alloy, L means the material is stainless steel, and M means the material is the highest grade of titanium alloy. All AP racing street calipers are aluminum alloy pistons. For example, CP8520-2S0R2 means that the piston is made of aluminum alloy. AP Racing athletic caliper pistons are available in stainless steel and titanium alloys, both of which are superior to aluminum alloys. For example, the CP9440-2S4L caliper piston is stainless steel and the CP5785-2S0MPD caliper piston is a titanium alloy.

"P" means that the piston can accept the cap. Without the letter, there is no cap and the cap cannot be accepted. C means that the piston has been capped. The role of the lid (usually a ceramic material) is mainly in heat insulation, preventing the heat from passing through the piston to the brake fluid leading to air resistance, but this technique is usually applied to athletic calipers, and the AP Racing street calipers do not match.

"D" indicates that the caliper has a cooling duct to match, and no indicates no air duct matching. This technique is also applied only to AP Racing athletic calipers.

In addition, the street calipers will add "BK" and "R2" codes at the end of the number (athletic calipers are not available). BK represents black, R2 represents red, and S10 represents silver. Such as CP8530-2SOR2 represents this is a red CP8530 caliper.

two. The difference between street calipers and athletic calipers

       Some unnecessary brake design on the track will become necessary on the road. AP Racing official data shows that, without changing the repair kits, the track brakes can only normally use 3000 to 10,000 miles (4800 to 16,000 kilometers) on ordinary roads. The track conditions are indeed very harsh, but there is no continuous maintenance inspection. Daily use will be more demanding!

       In the street kit, the caliper is equipped with a dust boot to prevent foreign particles from damaging the piston. In addition, the anti-sliding shrapnel is also fixed to fix the brake pads to reduce the noise of daily use. There is also a design that can not be found in athletic calipers! Athletic calipers often do not prevent corrosion corrosion through long-term maintenance, but corrosion protection is crucial for street calipers. AP Racing uses a special high-temperature paint coating to protect the aluminum caliper. Racing does not need to fight against road salt in winter, but street calipers need not only run through the winter, but also need to face different road conditions across the country. So the street caliper has more considerations and more stringent standards.

       In addition, many people can not distinguish the dust jacket and sealant, often confused. Here under the science, all calipers have Seal Seals, whose role is to ensure the tightness of the brake hydraulic system. The Dirt Seals only exist in street calipers and pull athletic calipers. The calipers used in formulas, RV races, and endurance races generally do not have a boot, as the dust jacket (rubber) at high temperatures (more than 200°C) will oxidize and deform and affect the normal movement of the piston. So, generally speaking, athletic calipers are not suitable for everyday street use, and street calipers are also not recommended for heavy loads.

three. Common caliper types

1.CP5317

Two-piston calipers

Structure: two-piece aluminum alloy casting

Suitable for 332mm*26mm brake disc

Piston area: 26.8cm2

Net weight: 1.5kg

Brake pad area: 33.7cm2

Color: red, black

Applicable scope: Rear wheel, 17-inch wheel hub, used with the former senior caliper. As before CP5200, CP9200 and so on.

2.CP7600

Senior Piston Caliper

Structure: two-piece aluminum alloy casting

Suitable for 295mm*24mm brake disc

Piston area: 45.6cm2

Net weight: 2.6kg

Brake pad area: 43.5cm2

Color: red, black

Applicable scope: front wheels, wheel hubs above 15 inches, light vehicles such as Fit, Swift, etc.

3.CP5200

Senior Piston Caliper

Structure: two-piece aluminum alloy casting

Suitable for 330mm*28mm brake disc

Piston area: 49.56cm2

Net weight: 2.4kg

Brake pad area: 57.4cm2

Color: red, black

Scope of application: Front wheel, 17-inch wheels, small and medium-sized vehicles such as: Civic, Golf, Fox, etc.

Note: The CP5200 is a rare street caliper with a return spring and is now discontinued.

4.CP9200

Senior Piston Caliper

Structure: Two-piece aluminum alloy forging

Suitable for 330mm*28mm brake disc

Piston area: 49.56cm2

Net weight: 2.43kg

Brake pad area: 57.4cm2

Color: red, black

Scope of application: Front wheel, 17-inch wheels, small and medium-sized vehicles such as: Civic, Golf, Fox, etc.

Remark: CP9200 is a forged upgrade version of CP5200

5.CP8530&CP8540&CP8560

CP8530 is a senior four-piston caliper, CP8540&CP8560 is a small four-piston caliper

Structure: Two-piece aluminum alloy forging

Suitable for 355 & 400mm*32mm brake discs

Piston area: CP8530-49.56cm2, CP8540-28.8 cm2, CP8560-22.9 cm2

Net weight: 3.35kg

Brake pad area: 64.6cm2

Color: red, black

Scope of application: CP8530-front wheel, 18-inch wheel hub medium-sized vehicles, such as: Audi A3L, BMW 3 Series, etc.

   CP8540&CP8560- rear wheel, generally with large six-piston calipers, such as CP8520, CP8521, CP8522

6.CP7040

Big Six Piston Calipers

Structure: two-piece aluminum alloy casting

Suitable for 362mm*32mm brake disc

Piston area: 50.1cm2

Net weight: 3.7kg

Brake pad area: 72.5cm2

Color: red, black

Scope of application: front wheel, 18-inch wheels, large vehicles such as: A6L, Alpha, BMW 5 Series, etc.

7.CP9040

Big Six Piston Calipers

Structure: Two-piece aluminum alloy forging

Suitable for 362mm*32mm brake disc

Piston area: 50.1cm2

Net weight: 3.7kg

Brake pad area: 72.5cm2

Color: red, black

Scope of application: front wheel, 18-inch wheels, large vehicles such as: A6L, Alpha, BMW 5 Series, etc.

Note: CP9040 is a forged upgrade of CP7040

8.CP8520&CP8521&CP8522

All three are big six-piston calipers

Structure: Two-piece aluminum alloy forging

Suitable for 410~380mm*36mm brake disc

Piston area: CP8520-62.5cm2, CP8521-58.6 cm2, CP8522-50.1 cm2

Net weight: 4.65kg

Brake pad area: 108.9cm2

Color: red, black

Applicable scope: front wheel, 19-inch wheel hub, medium-large vehicle

CP8520 - heavy duty SUV, such as Land Rover Range Rover, BMW X5, X6 and so on.

CP8521-larger vehicles, such as Nissan GTR35, BMW F10 5 Series, etc.

CP8522-Medium, BMW 3 Series, Audi A4, etc.

four. About caliper parameters

        The number of pistons: usually the greater the number of pistons, the greater the total piston area and the more uniform linear force of the caliper.

        Structural material: One-piece is better than two-piece, but due to cost issues, AP Racing all street calipers are two-piece. Made of aluminum alloy

        Brake disc size: lever principle, the larger the brake disc, the greater the braking torque

Piston area: Large caliper area with large piston area, but the piston area must be matched with the master car's master pump, but the area is too large but counterproductive

        Net weight: The caliper does not include the weight of the brake pads. Under the premise of ensuring the strength, the lighter the weight, the more weight the weight of the unsprung weight will be.

        Brake skin area: The larger the area, the better the heat dissipation and the lower the wear. The increase in the area of brake pads will also increase the friction coefficient, but the impact is not great.

        The area of the piston in these parameters and the size of the brake disc have the greatest impact.

Fives. Caliper and Vehicle Collocation

        This problem is the most common and the most easily overlooked issue. The main problem among this is the relationship between the area of the piston and the master pump. In general, the piston area of modified multi-piston calipers will be larger than the original factory. If the area of the modified caliper's piston is too large compared to the original car caliper, an excessively deep pedal stroke is required to make up for it, which may result in mid-front and even full-stage brakes being soft. For example, many riders have modified the CP8520 for their BMW 3 Series, Audi A4 and other models. As a result, the foot feel is very soft and the brakes are not enough. Unknown riders even think that AP Racing is just that way, but they do not know that because they are not professional, they spend money. This problem can be described as "chicken kill chicken."

        Take the recent fiery tenth generation Civic as an example, the front wheel brake calipers use large single-piston floating calipers and 282mm brake discs (effective radius is approximately 115mm), and the friction coefficient of the brake pads takes the Japanese average OE level of 0.35.

The diameter of the piston was measured to be approximately 56mm, and the area converted to 24.6cm2. Due to the special nature of the floating caliper, the theoretical area was equivalent to twice the actual area, so the theoretical area was 49.2 cm2. This data is comparable to AP RACING's several 4-piston calipers, such as the CP5200, CP9200, and CP8530-49.56 cm2, which can be perfectly matched! Even compared to several six-piston calipers with an area of 50.1 cm2, it is only about 1.8% smaller.

        If the brakes are upgraded to a CP8530+355mm (effective radius of 152mm) brake discs and a Ferodo Racing DS2500 brake pad with an average friction coefficient of 0.42, how much can the overall braking torque be improved theoretically?

49.56*0.42*152/(49.2*0.35*115)≈1.60. So the equivalent of the entire front wheel brake torque increased by 60%

If the brake is upgraded to a CP9200+330mm (effective radius of 139mm) brake discs and a Ferodo Racing DS2500 brake pad with an average friction coefficient of 0.42, how much can the overall braking torque be theoretically improved?

49.56*0.42*139/(49.2*0.35*115)≈1.46. So the equivalent of the entire front wheel brake torque increased by 46%.

       If the brake is upgraded to a CP8520+380mm brake disc and the Ferodo Racing DS2500 brake pad with an average friction coefficient of 0.42, how much can the overall braking torque be improved theoretically? Sorry, if you do so, your brakes are not as good as the original! CP8520 piston area of 62.5 cm2, a full 27% larger than the original size, you may step on the brake pedal in the end, brake pads and brake discs just started affectionate!

six. Is the brake really stronger?

       Before discussing this topic, we should first talk about the braking limit. We must know that the braking of a car is also limited. This limit is the ultimate grip of the car's tires (in scientific terms, it should be the maximum static friction), and the ultimate grip is affected by many The factors affecting are mainly the vehicle weight, the air pressure, and the friction coefficient between the tire and the ground. The original setting, the braking force is appropriate to be greater than the limit grip, when the tire is locked, the vehicle is sliding slightly less than the maximum friction of the tire friction (sliding friction is less than the maximum static friction), and trigger ABS. If you increase the braking force too much without upgrading the tires, you will only let the tires lock up too early and trigger the ABS, so you can't fully exert the braking effect. Therefore, when you upgrade the brakes, changing a set of tires with stronger grip can really improve the braking effect.

       But then again, the brakes still need to pay attention to a degree. If the brakes are too powerful, you can brake your car at an average speed of 2 g. Will your car be able to withstand it? Can the rider withstand it? Therefore, brake modification and even vehicle modification all need to consider these issues scientifically and in a balanced manner. The quality of the car calls for everyone to be scientifically modified and respected!