Thanks for the question. So my boy is driving it right now. It is only when he getting into it that this is an issue. If he drives it normal the belt is fine, no slipping through the entire RPM range.
Sounds to me like you need a Fan Clutch on that 7 blade fan. Those Fans can take 25 horse power to turn them. Your son gets into it and that solid mount 7 blade fan has got to spin up right now, putting lots of stress on a normal belt system. Put a fan clutch on it, then the belt will be driven as if it has an automatic transmission powering it. The fan clutch will be much much more forgiving to your belts, and still moves all kinds of air when you need it to.
