Nice design, thanks!
Quite robust and massive but I'll need that torque anyway. The idea is to have 2RC modules on board, so a total of 4 RC buggy motors coupled, to propel my vehicle. I'm not anywhere close, still doing some trial and error, researching etc.
In the beginning I wanted the gearbox to be shift-able using only 1 motor, so the auxiliary output of the rc module would have done the gear changes for me, but turns out there is no such design that's reliable as it also has to withstand a great deal of torque (coming from 4 RC motors). On the other hand I can't precisely set the driving ring to middle idle state with any motor (not even with mindstorms' servo) as the positioning is not accurate. Since I'm going for max speed, any slack gear change would result in cracking gears and the whole drive-train falling apart, so I need to get it right.
So right now I'm planning to have the mindstoms brain on board attached to it 2 sensors to detect shift requests, and 3 servo outputs, 2 of which will do the shifting itself, and one other for the AWD/RWD lock (possibly used as a launch control feature too). Should be no issue as it's easy to program, provided that it will know by itself which gear is engaged. On top of all this I got to have the 2 RC modules + 4 engines built into the structure.
I've done tons of tests on coupling the rc buggy motors, and turns out there is no point of not hard coupling them in my setup, they proved to be accurate enough, so going to be hard coupled.
As the output of the 'engine' will be hooked up to a 2 way clutch, flicking up will transmit the power to the gearbox and the wheels, flicking down will activate the break system on a different axle (leaving the vehicle go by its inertia) at the same time. Only thing's missing is the reverse, that's why I was looking for a 3+r rather than 4speed, BUT your design is more than helpful, I'll find a way to build it in to fit my needs. Thanks again!