Shifting transmissions

[liam.larkin]

I have been playing with a number of possible drive train designs for our team (272) for this upcoming year and for the future. A few of them lend themselves to the utilization of shifting transmissions. I have had little luck in the past with these style transmissions often under utilizing them and not fully taking advantage of their unique capabilities.

I have been looking at the ball shifter offered by VEX as a new possibility. Does anyone have experience with these. Are the stock gear ratios adequate? Is the design robust enough for a typical FRC competition/game? Has anyone modified them (ratios, gear material) with success? What about the stock gearing itself, spur or helical, undercut, overall backlash, tip relief, contact ratios? Any additional information and/or is appreciated.