Yes you are missing something--all the manufacturers give you a belt deflection measurement. It is irrelevant where it sits in the clutch your deflection is what matters.
Here is how I do it the easy way -- put the sled on a stand or suspend the back end somehow so you can run the sled.
Cycle the belt a few times by winding up the sled from a full stop to close to shift out to warm up the belt and the clutches. (or take it for a ride to get it all warmed up)
Now cycle the clutch through once and let the track stop by itself so the clutches shift back completely. Shut of the sled and loosen the secondary (nut) and unscrew it 1/2 turn--turn the secondary until the belt starts to tighten up. About 1 Revolution.
At that point I lightly tighten the nutted and run the sled again. I do that until the belt slightly creeps the clutch forward at idle .Shut here down and tighten the secondary nut usually about 1/8 to 1/4 turn tighten jam screw up and you are good to go. Now you will for sure start your ride in 1 Gear and not put undo wear and heat into your belt by always starting in second gear. Your rubbing will be a thing of the past.
After you have done this a few times you will know exactly what deflection your belt should have to work properly. If it squeals at idle you are slightly to tight. Hope that helps.
