Roadkill, if you have access to a lathe you could machine the outer edge of the Staton clutch drum a fraction of an inch to gain more clutch surface engagement.
I bought the clutch drum,shaft, spacers, collars and 1.375" spindle from bikeparts.com. I intend to retrofit it onto my Staton friction drive because the roller has a one-way bearing to reduce resistance drag. Also changing from 1.25" to 1.375" at the same time.
I'll also use these 1/2" ID bearings/shaft/collars to convert Staton friction assembly to gearchain drive, but that's a future project.