The pressure plate and the clutch centre need to match, in that the posts need to be the correct length to match the depth of the holes for the springs in the pressure plate. I've recently fitted a Sigma clutch to my bike and it was very noticable how much lower the spring post ends are on the new clutch compared to the old "standard" Ducati slipper clutch that came with the bike (748R). The Ducati pressure plate will certainly NOT work with the Sigma centre, if you were to fit the Ducati pressure plate on the Sigma centre then the springs would be coil-bound before you finished tightening them. Might the same thing apply here with an STM centre and a Speedy-Moto plate?
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