MC Garage Video: How Motorcycle Slipper Clutches Work and Why They’re Awesome

Slipper clutches are all the rage. Isn’t it time you learned what they do?

Twenty years ago, slipper clutches, which are also called back torque limiting clutches by engineer types, were reserved for racebikes. These days, slippers come standard on all kinds of streetbikes from performance machines like the Ducati Panigale to beginner bikes like the Kawasaki Ninja 300, and even sport-tourers and cruisers.

The whole idea behind a slipper clutch is that it prevents engine over rev and rear-wheel chatter, and helps keep the rear suspension working properly during hard engine braking caused by aggressive downshifts. At the racetrack a slipper clutch is helpful because downshifts are usually performed while hard on the front brake, so not only is there a lot of engine braking taxing the rear tire and suspension, but there’s very little static load pressing the rear tire against the pavement. Rear-wheel hop, a full-on skid, and even crashes can result. It’s not a good scene

On the street a slipper clutch might come into play when you downshift accidentally, make a sloppy shift in the wet or on a slippery surface, or if you downshift one more gear than you intended. Most folks don’t make those kind of mistakes, but if they do, a slipper could save their butt.

So keeping the bike’s back end calm is why slipper clutches are beneficial, but how do they work? It’s pretty simple, actually. The most common type of slipper clutch has ramps built into the inner basket and the pressure plate, and when the rear wheel begins driving the engine under deceleration, the ramps are forced together and they ride up each other. That pushes the pressure plate away from the clutch pack, which reduces the clamping force on the clutch plates and lets them slip past each other so that the rear wheel turns with less engine drag slowing it down and the engine revs aren’t pushed through the roof.

It’s the same action you’d get if you applied a little pressure to the clutch lever, but with a slipper clutch it happens automatically so you don’t have to put any thought into it. No rev matching or clutch finesse required.

A recent evolution of the slipper clutch is the “slip and grip” clutch. In addition to ramps that push the pressure plate out during hard engine braking, there are also ramps that force the plate in during acceleration. This puts additional pressure on the clutch plates to help prevent slippage. Since the “grip” ramps squeeze the clutch pack during acceleration, lighter (or fewer) clutch springs can be used, netting a nice easy pull at the lever.