We have never built our own shifting transmission, but this year we took the plunge and bought the Andy Mark 2-speed shifting gearbox's. They were great gave us good speed and power. Easy to mount, very little to worry about as long as you install them properly (lets just say that we killed one
). They are defiantly a lot easier than making your own, but they do come at a price
. Take a look at them:
http://www.andymark.biz/am-shifter2speed-gen2.htm
But making your own is always more fun
.