Ah yes, then the rotor gets bolted onto the hub and goes onto the crankshaft at the same time as the Centa housing being installed...

I had S&S and Harley on my mind. They have a sleeve that is a spacer and also has the crankcase seal wear points. The seal now rides on the new hub instead of the sleeve, gotcha.
So the Centa takes a special rotor?
Thanks for taking the time to explain, greatly appreciated.
Have a great evening.