[camtunkpa]

Aren,

I can offer two bits of advice. While your constraints are tight, I think you might be able to pull off a three speed transmission one of two ways. I'm thinking you'd have to use either custom planetary sets or ball shifting. The planetary transmission will take a bit more R&D, but could also be as easy as modifying a dewalt transmission to the gearing you want to achieve. There is some good information on how planetary transmission work on www.howstuffworks.com. As far a the ball shifting option, 222 has been using ball shifting since 2004. We have come away from the three speed the last 3 years because of the game. Here is our current iteration of two speeds http://www.chiefdelphi.com/forums/sh...ght=tigerdrive

We use 3/8" face 20 D.P. gears with a 14.5 degree pressure angle. I could see a three speed being built with about 1.5" between the plates or maybe a little less using the current gears. You could always use different D.P. gear and face widths to more suit your needs, but you're going to be running a fair amount of power through the gearbox and I wouldn't go much smaller without some major calculations to back it up. Anyway best of luck to you. If you have any questions about ball shifting you can either contact me or team222badbrad and we will help you to the best of our ability.