The clutch is a key component of a car, which is related to whether the car can start and drive normally. Once a malfunction occurs, it can lead to a decrease in work ability or a deterioration in handling performance. In fact, in addition to inherent defects, a large part of clutch failures are caused by improper adjustment and maintenance. To facilitate readers' understanding of the causes of clutch failures, this article provides a brief introduction on how to maintain and repair these causes.

（1） Function of clutch:

1. Transmitting power, driving device

2. Braking, parking

3. Cut off power, shift gears and speed changes

4. Vibration and noise reduction, safety protection

（2） Main failure modes of clutch:

1. Slipping

2. Incomplete separation

3. Trembling

4. Hair sinking

5. Abnormal noise

（3） Analysis of Failure Causes:

1. The reasons for clutch slippage are:

⑴ Incorrect installation/adjustment of the separation mechanism (e.g. too small free travel of the clutch pedal)

⑵ The wear of the clutch disc exceeds the limit value

Soak the clutch housing in oil (check the transmission and first shaft oil seal)

⑷ Failure of pressure plate assembly (e.g. membrane spring softening)

⑸ Incorrect selection of pressure plate assembly (too small reserve factor)

Before assembly, if there is too much grease in the keyway hole, wipe it off (there is oil stains on the friction plate surface)

⑺ Improper operation by the driver (such as placing the foot on the clutch pedal)

Improper selection of friction plates, overheating causing a decrease in friction coefficient or burning of the plates

Loss of compression force due to wear on the flywheel surface

Due to overheating, the pressure plate and flywheel warp, resulting in a decrease in contact area

2. The reasons for incomplete clutch disengagement are:

⑴ Incorrect installation/adjustment of the separation mechanism (e.g. excessive free travel of the clutch pedal, insufficient separation travel)

⑵ Separation refers to inconsistent heights

⑶ Wear of separation mechanism or presence of air or impurities in hydraulic system

⑷ Compression plate, driven plate or flywheel twisted and deformed

⑸ Failure of the pressure plate assembly (such as detachment of the support ring and insufficient lifting capacity of the transmission plate)

⑹ Guide bearing burned to death

⑺ Damage to the flower key hole or one shaft spline of the driven plate

⑻ Damaged separation bearing/fork holder

Immerse in oil and adsorb from the driven disc

Extreme wear or elongation of the separation rod (cable)

The reasons for clutch shaking include:

⑴ Separation of pressure plate assembly refers to fracture

⑵ Separation bearing (oil shortage) motion stuck

⑶ Failure of pressure plate assembly (such as support ring detachment, insufficient lifting capacity of transmission plate)

⑷ Damage to automotive related parts (such as guide bearings, input shafts, transmission gears, etc.)

⑸ Deformation, looseness, or wear of the separation mechanism

The installation of the pressure plate assembly is skewed, resulting in uneven separation fingers

⑺ Damaged or worn flower key holes or shaft splines on the driven plate

The elasticity of the damping spring weakens or breaks

The pressure plate, driven plate, or flywheel is twisted and deformed

Loose engine mount or aging damping pad

4. The reasons for clutch sinking are:

⑴ The separation force is too large, while the pump is selected to be too small

⑵ Unreasonable separation mechanism (leverage ratio)

⑶ Hydraulic system has air or impurities

5. The reasons for clutch abnormal noise include:

⑴ Separation bearings lack oil, burn and produce noise

Improper adjustment of the control mechanism, resulting in card issuance

⑶ Wear or damage to the damping system of the driven disc

⑷ Poor lubrication of the guide bearing resulted in burning

⑸ Worn and loose flower key holes or shaft splines on the driven plate

Separation refers to unevenness in height

The engine crankshaft and transmission shaft are not concentric

（4） Clutch Replacement Guide and Maintenance Methods

A. Always replace the entire assembly, such as the pressure plate assembly, driven plate assembly, or release bearing assembly.

B. Ensure to use authentic original accessories and inspect the corresponding old parts for integrity before installation.

C. Before installing the clutch, ensure that there is no oil contamination on the pressure plate surface and the friction plate surface of the driven plate.

D. Use guidance tools during installation.

E. Never allow a heavy gearbox to be suspended from the engine.

1. Carefully inspect the guide bearing for excessive wear, otherwise replace it.

2. Check all parts for oil contamination, otherwise replace the engine or transmission oil seals.

3. Check if the spline of the driven plate is excessively worn or damaged, which may indicate that the original transmission was not installed correctly.

4. Check for hot spots, cracks, or excessive wear on the surface of the flywheel, and also inspect the clutch face plate for the same condition to identify the cause and repair it.

5. Ensure the clutch release mechanism operates flexibly, check whether the release bearing installation assembly is severely worn or damaged, and replace all faulty parts.

6. Ensure that the surface of the pressure plate is clean and free of oil stains.

7. Before installation, ensure that the driven plate is not damaged and apply a small amount of lubricating grease to the keyway holes to ensure that the driven plate can slide freely on one shaft.

8. Ensure that the surface of the driven disc is clean and free of oil stains.

9. When installing the driven plate, a guiding tool must be used until the screw of the pressure plate assembly is tightened before pulling out the tool.

10. When installing the pressure plate assembly, the installation screws must be tightened diagonally.

11. Before reinstalling the transmission, ensure that all positioning pins are in place and that they are not severely worn.

12. Be careful not to damage the separation finger or ring when connecting the engine and transmission.

13. Correctly adjust the free stroke and working stroke of the clutch.

14. Check the installation condition of the engine and transmission to ensure that the clearance between the universal joint and the rear axle is not too large.

15. Check if the hydraulic system is working properly and clean and drain it if necessary.

16. Check the clutch cable to ensure that it is not stretched or worn in any position, otherwise replace it.

（5） Installation precautions for clutch and related components

1. Cover and pressure plate assembly: When installing the transmission shaft, the diaphragm separation finger is often damaged, and the breakage or deformation of the separation finger is often the cause of pressure plate assembly failure. Therefore, when installing the transmission, in order to avoid damaging the clutch release finger, it is necessary to check the clutch adjustment device and install it correctly according to the operating instructions.

2. Driven plate assembly: The clutch driven plate often undergoes twisting and deformation during transportation, more commonly during the installation of the transmission suspension. Therefore, the best way to install the clutch is to use a guiding tool.

3. Separating bearings: It is impossible to completely disassemble and inspect the separating bearings. It is uneconomical to use the original old parts when replacing the clutch, which often leads to clutch failure. To avoid abnormal noise and abnormal wear of the separation finger, it is recommended to replace it with a new one and inject a small amount of high-temperature grease.

4. Clutch cable: When replacing the clutch, it is recommended to replace the clutch cable at the same time. Adjusting the clutch cable to the limit position often causes the clutch to not engage. The clutch cable must be installed and adjusted correctly according to the operating instructions.

5. Flywheel: During the maintenance process of the clutch, the flywheel is often overlooked. Therefore, when installing a new clutch, the flywheel surface should be checked for grooves, hot spots, and cracks. Any defects on the surface of the flywheel must be repaired.

6. Guide bearing: If the guide bearing is worn, it can allow the transmission to run on one shaft; Floating” It will exacerbate wear and tear. This will cause vibration and noise. Therefore, when replacing the clutch, it is best to also replace the guide bearing with a new one.

7. Engine and transmission oil seals: Leakage of oil seals is a major cause of clutch failure, and even minor pollution can affect the effective operation of the clutch. Therefore, it is necessary to regularly check the oil level markings and replace suspicious oil seals.

8. Separation mechanism: If the separation mechanism is not adjusted properly or worn out, it will cause a significant loss of separation stroke, resulting in unclear separation. Therefore, all components of the separation mechanism, such as separation forks, cross shafts, sliding sleeves, and limit devices, must be able to operate freely, otherwise they must be replaced.

9. Separation bearing support: The unilateral wear of the separation bearing support can cause misalignment between the separation bearing and the separation finger, resulting in separation jamming or vibration,

10. Installation of engine and transmission: Any damage or wear of parts can cause the clutch to malfunction, so before installing the engine and transmission, check whether each part is intact.

11. Hydraulic system: Due to insufficient pressure or air infiltration in the hydraulic system, the clutch control mechanism operates inefficiently or does not work. Therefore, it is necessary to regularly check whether the main pump and the sub pump are leaking. When repairing the clutch, the hydraulic system should be cleaned and leak tested.

12. Automatic adjustment mechanism: Some clutch release mechanisms are automatically adjusted. When the automatic adjustment mechanism malfunctions, it may cause clutch slippage, abnormal wear of the release finger, and clutch failure. Therefore, when installing a new clutch, the cable should be adjusted correctly according to the instructions.

13. Adjustment of clutch: When installing the clutch, there may be different adjustment methods for the separation mechanism. Some devices require light contact between the separation bearing and the separation finger, while most require no contact. Incorrect adjustments can lead to clutch slippage, overheating, abnormal wear of the release bearing bearing surface and release finger, resulting in abnormal wear, component rupture, and shortened clutch life.

In summary, when the clutch experiences faults such as slipping, incomplete separation, shaking, and abnormal noise, it cannot be simply understood as a defect of the clutch itself. Often, it is caused by excessive wear, deformation, and cracking of parts due to improper use and operation, untimely inspection and maintenance. In order to restore the normal performance of the clutch and eliminate faults, it is necessary to disassemble and inspect the clutch and related components, and repair or replace the severely damaged parts.