The heart of the clutch mechanism is a stack of alternating plates. The number of plates varies between different types of clutches, but no matter the number you will have a combination of fiber and steel plates. The fiber plates have a layer of material bonded to both sides of a metal core (Typically Aluminum). The material was originally asbestos, but in modern times that has been replaced with organic resins and Kevlar. Whatever the material, its sole purpose is to create friction against the steel plates. The steel plates are just that, flat steel plates the are placed in between the fiber plates.
So, how does a motorcycle clutch work, anyway? Believe it or not, some riders have no idea that pulling that little lever on the left clip-on actually disengages the bike’s clutch. Many riders have only one concern when it comes to the inner workings of their machines-that they work. But digging into why it works and how it works opens up the fast paced, better than your buddy, potentially high-priced world of high performance.
What Is It?
A clutch is a mechanical coupling that allows the transmission of rotational energy to be engaged and disengaged, thereby isolating the engine from the rest of the driveline components.
What does that mean? It lets the engine spin while the transmission stands still when the clutch lever is pulled, and forces them to both spin together when the lever is out.
How It Works:
In most motorcycle applications the lever on the left bar acts via cable or hydraulic system to engage or disengage the clutch. Remember, the clutch is engaged (engine and transmission rotating together) when the lever is out. When the lever is pulled toward the rider, the coil springs in the clutch are compressed, allowing the stacked clutch plates to move independently.
The stack of clutch plates are arranged so that plain steel plates and friction plates alternate. One type of plate is connected via splines to the crankshaft while the other plates are connected to an outer basket that drives the input shaft of the transmission.
With the clutch lever pulled in, the springs are compressed-letting the plates spin freely while the engine and transmission are able to spin at different speeds. This makes gearshifts possible while at speed and allows the motor to run freely while the bike is at a standstill.
The clutch engages and disengages the transmission and final drive from the engine’s output. It allows you to disengage the transmission from the engine output in order to start the motorcycle moving from a complete stop, to come to a stop when moving, or to shift gears. When starting from a stop the clutch is gradually engaged while throttle is gradually increased simultaneously to make the motorcycle move (Friction Point). When shifting gears, the clutch is disengaged and held disengaged, the throttle is closed simultaneously(Unless using a QuickShifter), then the gear shift is moved to select a gear, and the clutch is then released (engaged) while simultaneously reapplying throttle. When coming to a stop, the clutch is disengaged, and held disengaged, the throttle is closed simultaneously, and brakes are then applied until stopped.