A back torque limiter, also known as a slipper clutch or a slipper mechanism, is a device commonly used in motorcycles to prevent excessive wheel locking or rear-wheel instability during aggressive downshifting or sudden deceleration. It helps manage the effects of engine braking and reduces the likelihood of the rear wheel sliding or hopping, which can lead to loss of control.
When a motorcycle decelerates rapidly or downshifts aggressively, the engine braking forces can cause the rear wheel to lock up or skid, especially if the rider engages the clutch abruptly or doesn't match the engine speed with the wheel speed. This situation can be particularly challenging during high-speed corner entry, where stability is crucial.
A back torque limiter addresses this issue by employing a mechanical or hydraulic mechanism within the clutch assembly. It allows the clutch to slip slightly when the engine braking forces are too high, enabling the rear wheel to rotate at a slightly faster speed than the engine. This slipping action reduces the sudden load on the rear wheel, minimizing the chance of lock-up or instability.
The back torque limiter works by using a ramp mechanism or a series of ball bearings that engage and disengage during engine braking. When the engine speed exceeds the wheel speed, the mechanism disengages, allowing the clutch to slip and mitigate the back torque. Once the speeds equalize, the mechanism reengages, transmitting power efficiently from the engine to the rear wheel.
By incorporating a back torque limiter, riders can confidently perform aggressive downshifts without worrying about destabilizing the motorcycle. It enhances safety, improves control, and reduces the risk of accidents caused by rear-wheel instability during rapid deceleration.