You have all got too much power.
I've done a season and a bit on my APTC clutch and it's only just started to grab on take off (see Snet race 2....), but no slipping.
Maybe it's because once I've got off the line I never pull the lever until the cooldown lap (or the graveltrap)??
I can't master the "slight slip to vary corner speed" technique, but maybe it only becomes necessary when you're fast?
Paul
15th year in DD #68 and getting slower by the year
1199, SS800 & 620SSie DD racer