This motor from Pololu has a long (0.365″ or 9.27 mm), D-shaped metal output shaft that matches the Pololu wheel 42x19mm and 32x7mm. The brass faceplate has two mounting holes threaded for M1.6 screws (1.6 mm diameter, 0.35 mm thread pitch), or you can use the mounting bracket or extended mounting bracket, which are specifically designed to securely mount the gearmotor while enclosing the exposed gears. We recommend the extended mounting bracket for wheels with recessed hubs, such as the Pololu wheel 42×19 mm.
Gear ratio: 29.86:1 No-load speed @ 6V: 1000 rpm No-load current @ 6V: 0.07 A Stall current @ 6V: 1.6 A Stall torque @ 6V: 0.57 kg·cm Max output power @ 6V: 1.5 W Extended motor shaft?: N Motor type: 1.6A stall @ 6V (HP 6V)