hmm, i ran my FAST clutch in my old 4mm cairo motor that made almost 80 hp for a good year. about 10 hillclimbs, 2 dune trips, and about 20 dyno passes with no issues whatsoever. then i ran that same clutch in my 4mm cub motor for a year without a lockup in prolly 10 more hillclimbs, and a dune trip. not to mention all the passes i had in my field testing and tuning..maybe you did set yours up wrong because mine worked great for 2 years on 2 different motors that made more than 70 hp easy.. :shrug: