I have a 98 vmax sx600 that I'm trying to get the primary sliding sheave off to replace. Does anyone have any tips on how to remove from the clutch and fixed sheave? I found a microfiche image of the clutch and the sliding sheave appears to be threaded, but moderate impact with a rubber mallet has done nothing...so far.
Any tips would be appreciated.

The sliding sheave does NOT screw off- the fixed sheave does, allowing you to remove the sliding sheave. You need a holding fixture specifically for the Yamaha clutch and the proper spider wrench. DO NOT attempt to disassemble the clutch without the proper tools, you will more than likely not be happy with the results.

make something to hold the spider in a vise or bolt to workbench. I used pieces of wood that fit between the spider screwed to a piece of 3/4 plywood. them make another tool to fit in the dowel holes on the fixed sheave heat center of fixed sheave. then turn clockwise with the fixed sheave facing up ... you can also buy these tools if you want.

the following pics show the set up...this is not my set up but it gives you the idea

best idea is to just sell the beast and drive the wifes 'doo'