I have a prototype of the gearbox and wheel made out. Since the motors are in the wheels I'm going to need some more beefy servos because of the weight. I don't really want to buy them Id rather make my own but I'm not sure if you can just simply hook a electric motor up to a servo channel. I want to build a gearbox with a worm gear for steering, how would I make the motor driving that return to the center when you let go of the steering wheel? Also if I did that how would I make it stop at a certain spot when I have the steering wheel all the way over to one side?

Heres some pics of the gearbox so far (no gears yet) and the wheel. One question about that also. The diameter of the wheel hub is 5 inches and the rubber wheels I have are the same so there will be no cushion. Should I get rubber tires that have cusion such as a 6-7 inch diameter wheel? or can I still use these rubber wheels I have somehow?

Thanks