Never had a P22 apart, but couldn´t they someway taper the part that connects the sheaves. The P-drive seems to hold together with that kind of solution?
Which forces you to pull the entire clutch just to change the spring.... The P-drive is nothing to copy, I've had several of them so I know. The P-drive is a heavy, unnecessarily complicated and expensive P85 clone needing constant service and frequent rebuilds....
How much of the problems are due to the spindle/center part being machined thinner to accommodate the roller bearing the belt rides on at the bottom?
I'm thinking that the material in the clutch taper is so thin that it flexes under load giving the clutch a chance to work itself free.
Keying the clutch to the crank, as it's done on the Rotax 850, could perhaps make it possible to go down in diameter on the crank taper enabling "giving back some material" to the clutch spindle.... if material thickness is the broblem that is.