Erratic Engagement

Problems with Erratic Engagement: 

Erratic engagement is most often caused by sticking flyweights in the clutch or the movable sheave binding on the hub. Learning how these parts function may help determine why there is failure. 

Increased engine rpm pushes the flyweights against the outer drum. This forces the movable sheave towards the engine, forcing the belt to travel at a greater circumference around the driver clutch. The belt’s force opens the driven pulley, decreasing the circumference the belt travels around the driven pulley. 

Decreased engine rpm forces the spring in the driven pulley to close the pulley forcing, increasing the circumference the belt travels. This action overcomes the flyweights’ force against the movable sheave, forcing open the driver clutch pulley and decreasing the circumference the belt travels around the driver clutch. 

When at idle, the driver clutch pulley will not be engaging the sides of the belt. The belt should be sitting loosely in the pulley, resting on the bronze bushing around the hub. These bronze bushings protect against the belt rubbing on the spinning hub while idling. During engagement, the bushings support a portion of the movable sheave. The sheave should move freely on the spline hub with no binding issues. 

Removing and cleaning the drive clutch can help with engagement issues. Use an automotive parts solvent cleaner, wiping away any dirt or lubricant residue. 

Note: Avoid using petroleum based lubricant inside the drive, between hubs or movable sheave. A petroleum based lubricant will char under the heat and pressure.