Car modification knowledge: can upgrading large brake discs improve braking capacity?
High performance vehicles need not only excellent engines and gearboxes, but also powerful brakes; Otherwise, after rapid acceleration, the vehicle cannot slow down effectively, and the vehicle will easily get out of control, so many drivers pay attention to refitting the brake.
There are three common operations:
Replace the large brake disc
Replace the multi piston caliper
Replace ceramic fiber brake pads, etc
Such operations are of little practical significance unless the three steps are carried out at the same time. The structure of disc brake includes brake cylinder and disc. The reason for deceleration depends on friction. In fact, the brake disc is fixed with the axle shaft and the wheel, and the brake disc rotates when the wheel rotates. On the contrary, when decelerating, the brake disc is clamped by the brake disc in the immovable position, and the wheel torque (rotational kinetic energy) is interacted by friction to realize deceleration.
Does it make sense to simply increase the brake disc?
Strictly speaking, it is meaningless and even affects the braking performance; Because the larger the brake disc, the higher the mass, the greater the inertia force during rotation; The more kinetic energy the brake pads need to overcome, unless the friction can be increased and the range is large enough, so that the effect of improvement can be achieved.
However, how does the friction change when the size and type of brake pads remain the same? There are two factors that determine the coefficient of friction.
Magnitude of positive pressure
Roughness of contact surface
Simply discussing the friction force does not need to consider the size of the connecting contact area. The core is roughness and positive pressure, which are multiplied to obtain the friction force; If the replaced brake disc is the same type of cast iron disc and there is no special design, these two factors will not change, and the braking capacity will obviously not be improved.
What is the significance of replacing multi piston calipers?
Pay attention to the details: "how significant" shows that it makes sense.
The improvement of the caliper piston of the braking system can improve the braking capacity, which can not be denied, but it is not so easy to upgrade; The caliper is a structure fixed on the brake disc and clamped on both sides. The brake action is that the booster pump adds force to the caliper piston to push the brake pad to clamp the brake disc and then start friction deceleration.
The function of piston is to push the brake pad close to and contact the brake disc. Ordinary scooters use single piston brake discs - single piston does not mean that there is only one piston, but a pair of pistons on both sides. Such a structure is not ideal. We can only say "enough".
The shape of the brake pad is mostly irregular arc or rectangle, and the piston can only add force to the middle position of the brake pad, so there will be the problem of high pressure in the middle part of the brake pad and low pressure on both sides; The core factor determining the strength of friction is "positive pressure + friction roughness", so the actual friction of brake pads is large in the middle and small on both sides. This will inevitably lead to the problem of weak braking performance, but the manufacturing cost of single piston calipers is the lowest, and the performance of ordinary scooters is also relatively weak, so they accept this kind of calipers.
If you want to improve the braking performance of the vehicle, you can choose 2, 3 and 4 piston calipers, which refers to one side here; The number of piston calipers is very good. Through the analysis of the wheel hub, there are several circular protrusions on the brake calipers. One protrusion is a pair of pistons, two protrusions are four pistons, and three protrusions are six pistons, which is basically the top.
More pistons act on multiple positions of the brake pad, positive pressure equalization can improve the friction, and can avoid the problem of uneven wear of the brake pad and brake disc; Therefore, upgrading multi piston calipers is still of some significance, but if you want to get the ideal effect, you often have to cooperate with the synchronous upgrading of oil pipes.
Significance of three-step simultaneous upgrading
Increase the brake disc, replace the brake pad and increase the number of pistons, which can significantly improve the vehicle braking capacity; The reason is that there will be a certain degree of deformation of the brake disc during high-speed friction, which is greatly affected by temperature. Increasing the size can change the deformation, and the "grip" between them will be improved. Moreover, the size of multi piston caliper is also relatively large. What is needed is supporting brake pads, and then the brake disc should be upgraded.
The friction coefficient of the brake pad is different. Of course, the braking performance can be changed according to the selection of parameters; For the brake disc, it is recommended to consider the ventilation disc, which has good heat dissipation effect and is not prone to thermal attenuation of braking force.
The last issue to consider is "cost". The cost of large-size brake discs and high-standard brake pads is not low, and the cost of multi piston calipers is even higher; The key point is that the general wheel hub still can't fit large calipers, so upgrading the braking system is to replace the wheel hub and tire together. However, the provisions of the modified vehicle can't change the wheel hub and tire size. If the size is changed, it can be punished according to the illegal modified vehicle and asked to restore the original standard.
This is the problem of refitting the braking system. Is there any plan to upgrade the braking system?