on the dura clutch, the belt is engaged all the time, the primary clutch also has a clutch built in, and a sprag bearing that is a one way clutch for the engine breaking. that's why you get the smooth starts,, no jerking , kind of like the clutch in a Honda. check out the vidieos on u tube. they aint cheap, but if you have to replace all the clutches, its about the same money, and comes with a new belt.