Slistack, I'm very interested in this as it allows me to use a single long and powerful motor to drive both wheels, put it under the board and still have a differential system. My question is, do you use it for the front truck or the rear truck?
As you can tell, both trucks (rear and front) turn on a skateboard. On the front truck, the outside wheel needs to be faster during a turn. Conversely, on the rear truck, its the inside wheel that needs to turn faster during a turn.
So if i'm going to use this, which truck would benefit from this?
Also, seems this is up your alley, have you looked into transmission/shifters system. I see some at AndyMark.com, but its quite expensive.