Motorcycle Slipper Clutch Operation and Adjustment.

A motorcycle slipper clutch operates by reducing  the pressure on the clutch pack when the rear wheel it trying to turn the engine. Road racing type slipper clutches have no effect on the clutch engagement when the engine is trying to drive the rear wheel.

In the above photo, the hub of the slipper clutch is disassembled. The base of the slipper is on the right, and the balls are placed on the ramps. The splined hub on the left is upside down. the ramps and dogs are identified. In normal operation, when the engine is trying to turn the rear wheel, the flat engagement dogs push on each other, and the clutch drives the motorcycle forward.

When the motorcycle is slowing for a turn (Engine Braking) the torque forces the ramps together, The ramps then ride up on each other, and this action lifts the splined part of the hub off of the base.

In the above photo, the hub is shown at rest. This is how it would be when the engine is making the motorcycle go forward.

 

In the above photo, the splined clutch hub is lifted a few mm off of the clutch base.  (look for the gap between the splines and the flat part of the hub) This is what happens when slowing from high speed with the throttle shut.

 

Clutch Stack Height

Clutch stack height is more critical in a slipper clutch than in a normal clutch. The slipper clutch tends to work the best with a clutch stack height that is about 1mm more than the distance between the clutch hub base and the pressure plate

In the above photo, the clutch has about 46.5mm of distance between the base and the pressure plate. Based on this measurement, you would want a stack height of about 47.5 to 48mm. Our clutches are designed to be at the optimal stack height with the Original clutch plates. Clutch shim kits with different thickness steel plates can be used to adjust this dimension,

Since disassembling the clutch to monitor the stack height is a bother, we have developed a method to indirectly measure the stack height without disassembling the clutch

In the above photo, we show a slipper clutch without plates. Here we are measuring the distance from the  top of the pressure plate to the top of the splines on the clutch hub. The dimension for this clutch is 4.6mm. Your slipper clutch may be different. Once you determine this dimension WRITE IT DOWN.

In this photo, we have jumped forward to show the clutch assembled with plates, and the pressure plate lightly clamped down.  We measure the distance from the top of the pressure plate and find out that it is now 5.7mm.

Subtracting this measurement from the initial one, ( 5.7 - 4.6 = 1.1 ) we find that our clutch stack height is 1.1mm more than the distance between the pressure plate and base ( PERFECT)

 

Judder Springs and other Plates.

Clutch plate order for slipper clutches may vary from the original method due to the clutch hub lifting off of the base as shown in the third photograph. In order to compensate for this, please pay attention to how you put the plates in the clutch.

When we describe the "First" plate in a clutch, we are referring to the one that is closest to the inside of the engine. The last plate is the one closest to the clutch cover (or your right foot).

The First plate in the motor would be a normal friction plate, as it is impossible for them to slip under the hub, and jam it open. The second plate in the motor is a normal steel plate. 

Here is where some motors vary. IN  SOME MOTORS, there is a special friction plate, as well as some thin steel rings that help the clutch engage more smoothly. While these usually the first plates in the clutch pack, they must be the third plates in, when assembling a slipper clutch.

Once past the third plate, all goes as usual.

If you need to adjust the height of the clutch stack, we suggest putting the shim plates near the pressure plate. this way, if you have to go in and readjust them, they are easy to get to.