Thatz what they make flat washerz for in varying thickness and diameters with the same 7/8th bore size. they pinch the inner race so only the bearing and outer race will spin. Oh, and as for the need for that pulley. All beltz will stretch over time and we all get ah bit lax in our P.M.in'. I personally have had belts get loose enough that they will reverse on the drive pulleys. Try swapping twin beltz on the shoulder of I-94 in down town Chicago even if you do travel with a spare set and have the toolz along for the ride. Trust me , Mother and all the other manufactures have done their home work on that one. It'z there for a reason, Jer