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Brake disc’s shaking

 Brake disc is an important part of the brake system,the material is mostly cast iron. Brake disc can be divided into ventilated disc, solid disc, smooth disc, drilled disc, slotted disc and  drilled and slotted disc. Brake discs and brake pads work together to achieve braking effect through friction loss and heat generation. However, we often encounter problems such as vehicle owner feedback brake shaking during normal use and sales, so today we will analyze common causes of brake disc shaking together.
一,The reason of brake disc shaking can be divided into the following categories:
1.The round run-out (flatness) of the installation surface is unqualified.
If the circular runout of the installation surface does not meet the requirements, some place is high,some is low, that is, it is not completely flat (there is no completely flat plane, but there is a certain standard, and it is normal and qualified only if it does not exceed this standard). The causes of unqualified circular runout of the intallation surface include 1. rusting of the surface 2. external force knocking (for example, when disassembling and assembling the brake disc, it is difficult to disassemble because of rusting, so it is necessary to knock and disassemble it with an iron cone. )

2.The question of Suspension part
If the suspension ball head and bushing is loose or cracked,it will cause shaking when braking or normal driving,Of course, this may also affect the four-wheel positioning parameters. If the parameters is wrong,it will also cause shaking during high-speed driving .

3.The problem of tire dynamic balance
We all know that after tire repair or tire replacement, it is recommended to do dynamic balance of the tire, because the tire has an air valve on it, which will cause the tire to be heavier in some places and lighter in others. if dynamic balance (lead block) is not done, the vehicle will shake during high-speed driving (this is explained from the physical principle because the centrifugal force generated by different masses is different in size, thus uneven force distribution will occur during rotation, which is reflected in shaking)

4.Brake pads are worn out
The eccentric wear here refers to wedge-shaped eccentric wear and eccentric wear with asymmetrical wear on both sides, because eccentric wear of brake pads will lead to eccentric wear or high-temperature deformation of brake discs as well. The eccentric wear of brake pads will lead to high, low, thin and thick brake surfaces of brake discs in some places,that means, it will destroy the circular runout (flatness) of the braking surfaces and cause shaking during braking. As for high temperature, if the brake disc is of uniform high temperature, it will not cause deformation of the brake disc. On the contrary, if it is not, it will cause deformation of the brake disc, such as watering at high temperature, etc.

5.Don’t Torque Diagonal Tightening according to the rules
If the screw is tightened in some places and loosened in others, it may cause the brake disc not to be completely horizontal and vertical, IT means if you check from the tire,the brake disc is convex in some places and concave in others (invisible to naked eyes),In this way, during the braking process, there will be frequent brake pad shaking, it is also springing of the foot, and when the frequency is high, it will shake.

二,The question of brake disc
1.The round runout (flatness) of brake disc surface is unqualified
The braking surface of the brake disc is not completely flat (it does not meet the standard, which has been explained above), that is, the flatness of the brake disc does not meet the requirements, which leads to the situation that the brake pads are in high place for a while and then in low place for a while in the process of braking.it is also springing of the foot,if the frequency is fast, it will shake (generally speaking, high-speed shaking, which is the reason). Of course, the movement track of the brake disc is fast, just like the snake's swing. The swing of the disc will drive other parts to shake, and the fast speed also reflects the shaking.

2.The brake is deformed by heat
During braking, the brake disc will generate very high heat. If it passes through a puddle at this moment, it will cause the brake disc to cool instantaneously. Uneven heating will lead to deformation of the brake disc, it will affect the flatness of the brake disc, or quenching will occur, resulting in brittle materials of the brake disc which are prone to crack.

3. The brake disc rusts
Rust here refers to serious rust, the rust cannot be completely removed by braking, which will affect the flatness of the brake disc and lead to shake.

4.The dynamic balance of brake disc is not well done.

It is the same with the tire dynamic balance introduced above, which is not explained again.

The following picture shows that there is a gap at the edge of the brake disc. This is the dynamic balance made by the factory . Because the brake disc cannot be dynamically balanced by adding lead blocks like tires, so it will be in this way.


2019-06-17 18:50:25