Step 6: Gearbox
Because the CIM motors I used are relatively high-speed low-torque motors, a gearbox was needed to reduce the motors' output speed to a useable level. I started out with two AndyMark Toughboxes, scavenged from my school. These are two-motor, two-stage gearboxes, so I had to cut them apart and recombine them to make them useful. First I removed one stage from each of the gearboxes, for a gear ratio of 14:50. I cut down the gearboxes to get rid of as much wasted space as possible, and aluminum-zinc brazed the pieces back together to get a 3-motor gearbox with one output shaft.
The gearbox was mounted to the scooter using the original bolt holes built into the gearbox and some aluminum angle bolted to the scooter's frame. Finally, a 21 tooth sprocket for #35 chain was fixed to the output shaft.