The front wheel brake calipers of many cars we see on the road are in front of the brake discs and some behind the brake discs. Generally speaking, the brake calipers behind are mostly luxury cars. So what causes the ordinary Is the position of the brake calipers different between a family car and a luxury car?
The first is that the definition is different. When the vehicle with the front caliper is driving forward, if you want to stop, the force of the brake caliper must be opposite to the force of the brake disc, so that the friction between the caliper and the disc can slow the vehicle, then When the car is driving forward, the brake disc rotates downward, and the caliper must provide an upward force to decelerate. In this way, the upward force and the downward force will make the vehicle more prone to nodding.
If it is a rear caliper, then it will be the opposite. The trajectory of the brake disc remains unchanged. The caliper at the rear needs to provide downward force to slow the vehicle. In this way, there will be two downward forces that can be balanced and will be reduced. The brake nod occurs.
The second is that it depends on the position of the steering system. All car brake calipers and steering rods are connected to the horns. In order not to interfere with each other, they must be placed one after the other. Under different driving layouts, they must be placed horizontally. Front-wheel drive cars generally use the design of front calipers, because the engine and gearbox are arranged horizontally before the front axle, and it is more convenient to arrange the steering rod after the front axle. For vehicles with vertical engines, the engine is generally installed vertically. After the front axle is arranged, the gearbox is immediately behind the engine, so there is no room for the steering rod to fit in the rear space, so the steering rod is arranged in the front, and the brake calipers can only be at the back.
In fact, another very important reason is the cost issue. Some brands do not have models with vertical engines, and all models have front calipers, so a series of models produced using the same mold can be lower in cost. The profit margin is also relatively large. The above is the reason why the front wheel brake calipers are at the front or at the rear.
What is the principle of car brakes?
Why does the brake caliper of a family car feel the same as the original brake after it is modified?
The principle of automobile brakes was actually summarized in 1635, which is Pascal’s principle;
That is, in a hydraulic system, if a force is applied to a smaller piston, the same pressure increase will be generated on another larger piston in the hydraulic system. If the area of the larger piston is smaller 10 times that of the piston, then the force acting on the larger piston will increase to 10 times that of the smaller piston;
One of the most typical applications is hydraulic jacks;
On both sides of it are two pistons of different sizes. When we use the lever to press down the small piston, the hydraulic oil inside will push the big piston up here, which can help us easily jack up a car with more than 1 ton; But here everyone needs to notice that the distance that the small piston moves downward is 2-3 cm, while the distance that the big piston lifts up is only 2-3 mm. This is completely different. This is also a key to Pascal's principle. ；
There is another brake system of the car;
When we step on the brake pedal, it will push the piston in the brake master cylinder and push the brake fluid to the four-wheel brake cylinder pistons, and then the brake cylinder pistons will push the brake pads and bite the brake discs to achieve the brakes. the goal of;
The brake master cylinder piston is the small piston in Pascal’s principle, while the larger piston is the sum of the area of the four brake cylinder pistons, because the area difference between the two pistons is still relatively large, and the brake pads are separated from each other. The brake disc is actually very close, and the brake master cylinder is also assisted by a vacuum booster, so we can stop a car weighing several tons with only a small foot force and a light step;
Then why is the braking effect similar to the original factory after refitting a more powerful 4-piston brake caliper, or even a 6-piston brake caliper?
Because the detailed data of the actual braking time cannot be measured here, we assume some data. For example, your original brake master cylinder piston area is 1 square centimeter, and the total area of the four brake cylinder pistons is 10 square centimeters. Now we want To stop the car at a speed of 100km/h and a distance of 40 meters, the sub-cylinder piston needs to be pushed out at least 1 cm away, and a force of 100 Newtons is applied to allow the brake pads and brake discs to fully friction before stopping. Then according to Pascal's principle, to achieve this condition, the master cylinder piston needs to apply a force of 10 Newtons and push the piston to move 10 cm to successfully stop. Then you can step on the brake pedal of 10 cm at this time.
Due to the replacement of pistons and more modified calipers, theoretically, the total area of your brake cylinder has become larger;
Assuming that it has changed from 10 square centimeters to 20 square centimeters, because the original factory is basically a single piston, and the modified caliper starts with at least 4 pistons, so now we need to push the piston of the sub-cylinder to a distance of 1 cm and apply 100 Newtons. Force, you need the master cylinder piston to exert a force of 5 Newtons, but it needs to be advanced by 20 cm, that is, the brake pedal needs to be stepped deeper, but because when we step on the brakes, we don’t care how much force is needed. , We will only step on it with all our strength, so when we need to step deeper to stop the car, from the subjective feeling of the driver, we will feel that the brake has become softer;
The above is just to change the brake caliper from the perspective of Pascal's principle. It is not the whole picture. Another key to the braking force is another friction area;
This is the advantage of modified brake calipers. Larger calipers can often match larger and stronger brake pads and brake discs. This means that the friction area when braking is larger, the brake arm is longer, and the heat dissipation capacity is longer. Stronger; then back to the example just now. With a larger friction area and friction force, there is no need to push the sub-cylinder as much as 1 cm, maybe only 0.5 cm is enough, and then with a force of 100 Newtons, you can The car was braked, so the final conversion is actually similar to the original brake distance. Therefore, the modification of the brake system is just a few data that affects the braking performance.
So why are there so many people admiring modified brake calipers?
The reason is actually very simple. Although the effect of the first few feet of the modified brake caliper may be the same as that of the original factory, as the temperature of the brake system rises, the modified brake system has a stronger heat dissipation capacity than the original factory. The attenuation comes later, and there are even some high-end modified brake systems that require a certain temperature to achieve the best braking effect. Therefore, cars with modified brake systems are often higher than the original factory at the driving limit of the vehicle. Yes, but the maintenance costs will also be much higher, so this is your own choice;
One more safety reminder, if your original brake system is used continuously or overloaded during continuous downhill, thermal attenuation may occur;
This means that the brakes are getting less and less effective, even if you use the brakes hard, there is not much deceleration effect. At this time, you should stop the car slowly in a safe place, and then wait for the brake system to cool down for a while before continuing.
At this time, the car can’t move, and the air conditioner can’t be used. In the hot summer, it’s just unbearable, but it doesn’t matter. We can use the car cooling spray and spray directly on the clothes, such as chest, back, underarms, and thighs. Wait for the location so that even if there is no air conditioning, you can continue to feel cool for two hours. （Don’t put the cool spray in the car）
If you have to ask me, how can you quickly improve the braking performance without spending a lot of money or making major modifications?
It's actually very simple. Just change to a set of softer brake pads, harder brake discs, and 4 good tires. As for why the brake pads and brake discs should be soft and hard, you can express your opinions in the comment area. , Looking forward to interacting with you;