Clutch throwout bearing (clutch release bearing) introduction

The clutch throwout bearing (also known as release bearing or release bearing) is an important part of the clutch system in manual transmission vehicles. Its main function is to push the clutch pressure plate when the driver depresses the clutch pedal to separate the clutch disc from the flywheel, thus cutting off the power transmission between the engine and the gearbox. This process makes shifting smoother and reduces the feeling of shock when shifting gears.

 Symptoms of a worn throwout bearing

When the clutch throwout bearing is worn or faulty, the following symptoms may occur:

1. Strange noise:

   - Symptom: A distinctive noise, such as a clicking, squeaking, or whistling sound, may be heard when the clutch pedal is depressed or released.

   - Cause: The ball or race inside the bearing is worn, resulting in poor operation and noise.

2. Change in clutch pedal feel:

   - Symptom: Clutch pedal travel becomes longer or shorter, feels out of place and may be accompanied by a hard or soft sensation.

   - Cause: When the bearing is worn, the motion characteristics of the whole clutch system change, resulting in abnormal pedal travel and force.

3. Difficulty in shifting gears:

   - Symptom: The driver will feel great difficulty in shifting gears and may require greater effort to complete the shift.

   - Cause: Failed throwout bearing cannot push the release fork correctly, resulting in the pressure plate not being able to completely disengage from the clutch disc, thus affecting the gearshift operation.

4. Incomplete clutch disengagement:

   - Symptom: Stuttering sensation when shifting gears, sometimes even unable to put it into gear.

   - Cause: Failed bearing cannot provide enough thrust so that the pressure plate cannot be completely disengaged from the clutch disc, resulting in incomplete separation.

5. Clutch slipping:

   - Symptom: When accelerating or climbing a hill, the vehicle behaves feebly and the engine speed increases but the vehicle speed does not increase.

   - Cause: After the clutch throwout bearing fails, the pressure plate cannot press the clutch disc properly, resulting in clutch slippage.

6. Vehicle stalls:

   - Symptom: The vehicle may suddenly stall when starting or shifting gears.

   - Cause: The clutch throwout bearing fails causing the clutch to fail to disengage properly, and the power connection between the engine and transmission is not completely disconnected, resulting in excessive load on the engine and stalling.

7. Clutch pedal vibration:

   - Symptom: The pedal may vibrate abnormally when the clutch is operated.

   - CAUSE: Worn bearings cause the clutch system to move unevenly, causing vibration.

8. Free stroke variation:

   - Symptom: The free travel of the clutch pedal may increase.

   - CAUSE: Worn bearings do not effectively transmit pedal movement to the pressure plate.

9. Starting Shake:

   - Symptom: Vehicle may judder or have discontinuous power transmission when starting.

   - Cause: The clutch fails to smoothly disengage and engage, resulting in erratic power transmission.

10. Decreased acceleration performance:

    - Symptom: The acceleration performance of the vehicle is affected when the engine speed is increased.

    - Cause: The clutch cannot be completely disengaged, affecting power transmission.

11. Abnormal Wear:

    - Symptom: Prolonged release bearing problems may also lead to premature wear of the clutch disc and other related parts.

    - Cause: Failure of the release bearing leads to a reduction in the overall performance of the clutch system and accelerates the wear of other components.

 Common causes of clutch throwout bearing wear

1. Insufficient lubrication:

   - Cause: Release bearings usually require good lubrication to reduce wear. However, in practice, due to improper maintenance or design constraints, the bearings may not receive sufficient lubrication, resulting in premature wear.

2. Frequent half linkage:

   - Reason: Driver frequently operates in half-clutch state, such as keeping half-clutch for a long time when starting, which will make the release bearing in high friction state for a long time, generating a large amount of heat and accelerating the wear.

3. Improper free travel:

   - CAUSE: Incorrect setting of the free travel of the clutch pedal may cause the release bearing to come into contact with the pressure plate and be subjected to pressure even when the pedal is not pressed, thus accelerating wear.

4. Operating habits:

   - CAUSE: Some driving habits, such as rapid acceleration, rapid braking, and especially frequent gear shift operations, can increase the burden on the release bearing.

5. Environmental factors:

   - CAUSE: Poor environmental conditions such as high temperature, dust and moisture can also increase the wear of the bearing.

 Methods of determining whether there is damage to the clutch throwout bearing

1. Listen for abnormal noises:

   - Method: If a rustling sound is heard when the clutch is pressed into semi-linkage, this may be a sign that the release bearing is worn out. Similarly, if you hear a noise similar to metal friction in the process of gear driving, it also implies that the release bearing may have failed. 

2. Observe the engagement condition:

   - Method: If the clutch release bearing is seriously damaged, the clutch may be difficult to engage properly, thus affecting the car's shifting and driving performance.

3. Feel the operating experience:

   - Method: Ideally, the clutch release bearing should operate smoothly without any obstruction, stuttering, or ear-splitting noise. If you feel any abnormality in the course of use, it may mean that the release bearing is faulty.

 The effect of clutch throwout bearing wear on the vehicle

1. Difficulty in shifting gears:

   - Impact: A worn release bearing may cause the clutch to fail to fully disengage, affecting smooth gear shifting.

2. Poor power transmission:

   - Impact: affects the power transmission from the engine to the gearbox, resulting in reduced acceleration performance.

3. Strange noise and vibration:

   - Affects: Increases noise and vibration while driving, affecting driving comfort.

4. severe wear:

   - Impact : Long-term wear may lead to premature damage to other clutch components (e.g. pressure plate, clutch disc).

5. safety hazard:

   - Impact: In extreme cases, complete damage to the release bearing may result in an inability to shift gears, affecting vehicle handling and posing a safety hazard.

 Summarising

The clutch throwout bearing is a key component in the clutch system, and its main function is to help separate the clutch disc from the pressure plate when shifting gears. Symptoms that may result from a worn throwout bearing include abnormal noises, changes in clutch pedal feel, difficulty in shifting gears, incomplete disengagement, clutch slippage, stalling of the vehicle, pedal vibration, changes in freewheeling travel, shaky start, reduced acceleration and abnormal wear. If any of these symptoms occur, it is recommended to have the clutch inspected and repaired by a professional repair shop immediately to avoid further damage and ensure driving safety. Regular inspection and maintenance of the clutch system, especially the throwout bearing, can effectively prevent these problems.