How a Transmission Clutch Works
When your car is stopped or coming to a stop the engine needs to be disconnected from the transmission or the engine willstall. Withautomatic transmission vehicles a torque converter is used to separate the two units, but with manual transmission vehicles a clutch assembly is used to do the job. This clutch kit or unit is composed of a clutch disc, pressure plate, throw out and pilot bearings. (Some front wheel drive vehicles do not use a pilot bearing). Both types of vehicles use aflywheel but are designed a little differently.
An automatic transmission has a lighter weight unit that the torque converter bolts directly to and is sometimes referred to as a flex plate. A manual transmission flywheel assembly is made heavier to help engine inertia and to make shifting smoother. The clutch pressure place bolts to the flywheel trapping the clutch disc in-between. The throw out bearing presses against the pressure plate to engage and release the disc. The pilot bearing is mounted in the flywheel and holds the input shaft for the transmission steady.
Most clutch assemblies operate on the same principle; hold a clutch disc against a flywheel under pressure with the ability to release the pressure to allow the clutch disc to freewheel. The clutch disc is connected to the transmission using an input shaft to the transmission gears and then through to thedrive shaft oraxles.
When replacing the clutch assembly always resurface the flywheel clutch disc surface. As the clutch wears it can cause the flywheel surface to become un-even, much like a worn brake rotor. If a new clutch disc is installed on and old flywheel it can cause the clutch to not operate properly. If the flywheel is dual stepped (example shown) it must be machined the same way or the clutch clamping pressure will be incorrect causing the clutch to slip or not disengaged.
There are two different types of clutch activation methods. Some manufactures use a cable that is fastened to the clutch pedal and then to the clutch fork. While other manufacturers use a hydraulic clutch master cylinder that is connected to a slave cylinder which is positioned at the bell housing, also connecting to the clutch fork. When the clutch pedal is depressed it will force the clutch fork onto the pressure plate causing the pressure plate fingers to release the clutch disc.