Slipper clutch

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Slipper clutches are specialized clutches developed for racing motorcycles to mitigate the effects of engine braking when riders would decelerate as they entered corners. They are designed to partially disengage or "slip" when the rear wheel tries to drive the engine faster than it would normally. The engine braking forces in conventional clutches will normally be transmitted back along the drive chain causing the rear wheel to hop, chatter or lose traction. This is especially noted on larger displacement four-stroke engines, which have greater engine braking than their two-stroke or smaller displacement counterparts. Slipper clutches eliminate this extra loading on the rear suspension giving riders a more predictable ride and minimize the risk of over-revving the engine during downshifts. Slipper clutches can also prevent a catastrophic rear wheel lockup in case of engine seizure or transmission failure. Generally, the amount of force needed to disengage the clutch is adjustable to suit the application.

Slipper clutches have been used in most high displacement four stroke racing motorcycles since the early 1980s. Honda introduced the slipper clutch with the debut of the FWS1000 in 1982 at Daytona, but it failed because the design wore out the clutch. Slipper clutches were also used in Honda's 750 Interceptor factory superbikes that same year. Before long slipper clutches could be found in nearly every big bore four-stroke race bike. Slipper clutches are now gradually being installed on production four-stroke motorcycles such as the Yamaha YZF-R6, YZF-R1 LE and the Kawasaki ZX10 R, and are available as retrofit for many other models.

Slipper clutches have also been used to a lesser extent on automobiles, primarily those powered by motorcycle engines. Slipper clutches can be found on racing remote control cars.

One-way sprag-type clutches have also been used for the same purpose, but are generally not adjustable for disengagement force.