There are generally three main components in a clutch kit. With some, you might find an alignment tool included to make the process a little easier, and in others, maybe even a pilot bearing.
Clutch disc
Pressure plate
Release bearing
Optional: alignment tool
If you’re buying a performance clutch kit, there’s a chance you could find a lightweight flywheel included in your bundle.
1. Clutch disc
The clutch disc—often called a clutch plate or friction disc—provides the grip between the flywheel and clutch plates, delivering the power from the engine to the transmission (the gearbox).
To provide the necessary grip required to transmit all the power between the rotating discs, each side of the clutch disc is constructed from robust friction-supported materials designed for long life and exceptional performance. The clutch disc is fixed to the pressure plate, which, in turn, is mounted to the flywheel.
There are additional clutch plate springs mounted on the inner hub of the clutch plate. They act as extra dampeners to soften each connection and gear change as the clutch disc connects with the flywheel.
At the centre of the clutch disc sits its splined hub. This splined hub transfers the movement of the flywheel to the gearbox through the transmission shaft, but only when the clutch plate is firmly held between the flywheel and the pressure plate.
2. Clutch pressure plate
The pressure plate’s key component is its spring. The spring operates the movement of the pressure plate, forcing the clutch plate against the flywheel when the clutch pedal is released. The pressure plate and spring are housed in a cover. The cover is fixed to the flywheel leaving each component free to move independently.
The pressure plate spring isn’t the typical metal coil we usually associate with springs. Instead, it’s a round plate known as a diaphragm spring. These circular steel discs have a hole in the centre (necessary for the transmission shaft) and are radially slotted, leaving ‘release fingers’ that delivers the required movement and spring action.
3. Release bearing
The clutch release bearing (also known as the throwout bearing) sits against the pressure plate diaphragm spring. When the clutch pedal is depressed, it pushes the centre of the spring inwards, releasing the outer edge and the clutch disc from the flywheel.
The release bearing’s job is to absorb the rotary motion of the diaphragm spring and the pressure plate while disconnecting the disc from the flywheel.
4. Alignment tool
Each clutch kit is different, operating with its manufacturer’s splined hub at the centre of the clutch plate. Manufacturers often include an alignment tool with the matching number and arrangement of splines to the hub to ensure exact alignment. This ensures that the alignment between the pilot bearing (located in the flywheel) and the clutch plate is precise.