So I have taken the Hustler on several rides so far and in total have put maybe 10 hours of ride time on it since I built it. Although it runs great on dry hard ground it seems lacking in low end torque. I determined today the belt is slipping. I went through a mud hole and it wouldn't even spin the tires. Belt was slipping at the drive clutch. After 10 hours riding the belt is 1 1/8 wide. The engine compartment is dry as a bone - no oil or water on the belt. Engine is not lacking power.

Belt and drive clutch both were new (10 hours ago). The drive clutch is a Comet 780 from mfg. supply. Spring in driven clutch is presumably stock. It has no color other than metal brown. 20 horse opposed Briggs stock engine. Tires are rawhides, either 21 or 22's. Belt alignment is spot on. I think the belt should be a tad tighter but when I put all this together the driven clutch would spin slowly at engine idle (tighter would have made that worse, of course).

As I see it, the belt can only be as tight as the drive and driven clutches will bite it. will heavier weights in the drive clutch, and the famous red spring in the driven, give me more bite on the belt?

Thank you in advance for your thoughts.