A clutch disc is a component of the clutch assembly in a manual transmission system. In order to effectively switch between gears in your manual transmission, it is necessary to momentarily disengage the transmission from the engine. Otherwise, your vehicle would be in motion anytime the engine was running. The clutch is the connection between the engine and the transmission and can be alternately engaged and disengaged.
The way the clutch works is through friction between the engine flywheel and the clutch disc. The flywheel is connected to the engine crankshaft and spins with the engine. The clutch disc is connected to the input shaft of the transmission. The disc is coated with a sacrificial friction material that causes it to grab hold of the surface of the flywheel when pressed against it by the clutch pressure plate. This is the case under normal operating conditions with the clutch engaged. Since the transmission input shaft is connected to the clutch disc, the shaft turns along with the engine.
When you press the clutch pedal, tension from the pressure plate is relieved, and the clutch disc is freed from the flywheel. In this condition, the engine spins independently of the transmission so that you can select a different gear.
Most technicians will advise that all of the components of a clutch assembly should be replaced at the same time. This is for a couple of reasons. First of all, the time that it takes to replace one of the components of a clutch is essentially the same for replacement of the entire assembly. It is also likely that, if one component is worn, the other components are in a similar condition. Therefore, it is common to replace the pressure plate, pilot bearing, and release bearing along with the clutch disc.
To replace a clutch disc, a technician must first safely lift and support your vehicle in the air for access. From there, a typical clutch assembly replacement consists of the following: