Pinion Gears

Let’s say you want to increase the speed or torque of the vehicle; this can be done by simply changing the gearing. There are two gears that we work with to modify this; the pinion gear and the spur gear. The pinion gear is attached to the motor’s output shaft while the spur gear is attached to an output shaft on the transmission. Changing these gears alters the ‘gear ratio’; a higher ratio equals more torque and acceleration but less top speed while a lower ratio equals less torque and a higher top speed. It is also good to note that a lower ratio can also build more heat, so it’s a good idea to monitor after changing the gearing. Pitch denotes the size of the teeth on a gear; the lower the number, the bigger the teeth. 

If you decide to upgrade your motor from stock to something a little faster, you’ll need to adjust your gearing as well. Gearing is usually calculated for a specific motor (especially in an RTR) for a good combination of speed and torque. If you put a faster motor in your rig and don’t change the gearing to match, you could overheat your motor and/or ESC, resulting in a failure. 

Castle offers pinion gears in 5 different pitches. Our Mod 1.0 and Mod .8 (32 pitch) have a 5mm bore and are used on our 1/8th scale motors for 1/8th scale vehicles, the Mod 1.5 gears with an 8mm bore for our 2028 motor and 1/5th scale vehicles. Our newest offerings include MOD1 8mm bore for 1/6th and 1/7th scale cars and 48 Pitch 5mm bore for 1/10th scale cars. 

32-pitch, 5mm bore          48-pitch, 5mm bore          Mod-1, 5mm bore       Mod-1, 8mm bore       Mod-1.5, 8mm bore