so the purpose of zero end play is longer life of thrust bearing..interesting and i think it may help a little (not much though). I think clutch gap has more to do with the pressure the thrust takes.
Btw, are .21 motors harder on thrusts than .12 motors?Because on .12 motors, thrust failure is not common.
Serpent 720 09 mega zx 12 dsII+, Serpent 733 nova 353 tuned/sirio XXXV
Futaba, Graupner, Hudy, RB fuel