all F2's had the torque sensing. The outer hub is keyed to the shaft. The inner sheave is attached to the outer torque cam assy via three pegs and actually floats on the shaft, the outer cam is spring loaded out to tighten the belt somewhat. The spring assy also has an inner cam that splines on the shaft. This unit can be removed as an assy and is generally assumed unrepairable. There is also a snap ring that serves only as a spacer between the outer bearing and the inner cam and splines. When under no load the assy spins together. When placed under load the outer sheave grips the belt but will not entirely pull a heavy load, thus belt slippage tries to occur. The inner sheave as stated floats thus it tries to stop with the belt, as it slows down the cams come into play and the inner sheave and outer cam will have to 'climb' the ramp to really slip. As the outer cam and inner sheave do this climbing proceedure it forces the inner sheave in and thus tightens the belt and in actuallity does not slip due to the cams now being locked together and the inner cam assists power transmission via the splines. We have seen broken springs, but worn sheaves in the hub area, over greasing and grease on the belt, misadjustment (1_8" between the bottom sheaves at slowest speed),worn belts on either side, or even the absence of the snap ring spacer will cause slippage. A clutch that is slipping will prevent the belt from tightening on rare occasions. The number one problem though is the outter bearing on the input shaft has wallowed out the metal at the base of the splines thus allowing the shaft to move a few thousands of an inch rearward thus putting the sheaves out of square with the main clutch shaft. Run the unit at high idle and go from low variable to fastest speed, if you feel an increase in vibration, you gotta problem more than likely.
