Auto clutch system parts

Clutch system: key insights into component performance, mounting, diagnostics, and durability

A clutch is used when shifting gears to disconnect the engine and gearbox for a short time and reconnect them again smoothly. It also serves to protect the transmission from overloading and to dampen vibrations produced by the running engine.

Clutch design

Its main components are:

• Flywheel – this is mounted onto the engine crankshaft. It serves as a driving member for the clutch and dampens vibrations.
• Clutch cover assembly – this consists of a clutch cover, pressure plate, and diaphragm spring. A clutch cover is a housing which is securely connected to the engine flywheel. The diaphragm spring exerts pressure onto the pressure plate, which presses the clutch disc to the flywheel. The pressure plate is connected to the cover with drive straps. When the clutch is disengaged, the pressure applied by the diaphragm spring decreases and the pressure plate detaches from the clutch disc.
• Clutch disc – this is installed on the gearbox input shaft. The spline joint enables the disc to move along the shaft. When the driver shifts gears, this disc is pulled away from the flywheel and the torque is no longer transmitted. Both sides of the disc have friction linings on them to provide the required friction force for torque transfer.
• Release bearing – this is installed on the rotation axis of the assembly. When the driver depresses the clutch pedal, the bearing presses the diaphragm spring fingers and releases the pressure plate.
• Clutch fork or lever – this moves the bearing when the pedal is depressed. The fork is connected to the pedal via a cable and the lever via a hydraulic drive.

Maintenance tips

1. Always start moving with the first gear engaged. The only exception is when you start on a slippery surface.
2. Press the clutch pedal with a quick movement all the way down but release it slowly to avoid slipping.
3. When you stop for quite a long time, for example at traffic lights, try shifting to neutral: that will reduce the load on the release bearing.
4. As soon as you’ve shifted to the required gear, remove your foot from the pedal to avoid pressing it accidentally.
5. Do not overload your car.
6. If your vehicle is stuck and wheels are spinning, it is not recommended to use the rocking technique. This way you can easily overheat and burn the friction linings.
7. Do not downshift when driving downhill.
8. Try to drive calmly and carefully. Sharp acceleration as well as the habit of controlling your speed using the clutch lead to the premature failure of the system.

Symptoms of malfunction

Increased pedal travel indicates issues with the actuating mechanisms. The cable might stretch, the master or slave cylinders may leak fluid. A burning smell inside the car appears when the assembly components are slipping. This problem is often followed by reduced vehicle performance, increased fuel consumption, and can even lead to engine overheating. Difficulties when shifting gears, jerking, crunching sounds, or unusual noise might be signs that the clutch isn’t completely disengaged. Sometimes, the driver may feel judder when the clutch is engaged. This happens when oil gets onto the friction linings, the diaphragm spring is deformed, the engine mounts are loose, or splines on the clutch disc are worn.

Causes of malfunction

Incomplete clutch disengagement might be caused by deformation of the clutch disc, wear and tear of its splines or friction linings, as well as by a weak diaphragm spring or faulty actuator mechanism. It often results from splined hub corrosion caused by insufficient lubrication. Slippage of the mechanism happens for the same reasons. Deformation of the discs, in turn, may be caused by incorrect installation or clutch overheating because of aggressive driving.

Sometimes, clutch slippage or jerking during its operation originate from oily friction plates. This may be caused by leaking gearbox input shaft and crankshaft seals or an incorrectly adjusted hydraulic actuator.

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Clutch system for popular car models

• Clutch for Ford Focus
• Clutch for Ford Fiesta
• Clutch for Citroen C1
• Clutch for Renault Clio
• Clutch for Peugeot 207
• Clutch for Vauxhall Corsa
• Clutch for Toyota Aygo

Useful information on functions, causes of malfunction, diagnosis and replacement intervals

• Car Clutch: problems and replacement cost
• Symptoms of a Bad Clutch Master Cylinder