Rear belts on a Whizzer never slip when adjusted correctly even when wet. Many motor bikers want to convert from chain to belt drive because of low maintenance, silent, and clean. If you convert to an automatic clutch you can tighten both belts so they never slip.
Yes I still make automatic clutches for both vintage and new edition Whizzers. They are 100% American made, have a one year warranty, and have shipped hundreds of them. Biggest problem is to keep up with demand, as it sells for about $60.00 more than the Taiwan version [90 day warranty $175.00 EBay], and is about 500 percent better [it actually works for thousands of trouble free miles].
We make it in 4 versions:
vintage 10 x 1 [for 26"]
vintage 8.5 x 1 [for 24" & 20"]
new edition 10 x 1 [26"]
new edition 8.5 x 1 [24"]
Have fun,