Much like the scale of RC vehicles varies, motors vary in size as well. The most common
motor sizes are: 540 (the most typical motor on the market, used for most 1/10-scale
applications), 550 (usually used for large 1/10-scale vehicles like 4X4 short-course), and
1/8 scale (used for 1/8-scale vehicles and large monster trucks). 1/18-scale and “mini”
cars generally use 370 or 380 motors. The number designation refers to the length of the
motor’s “can” in millimeters, but for many motors, it’s only an approximation. Everything
being equal, larger motors generally produce much more torque while also consuming
more power. For the most part, every vehicle is designed to be used with a specifically
sized motor, and there are plenty of motor options available in all sizes.
Sensorless on the left, sensored on the right. A sensored motor is
easily identified by its rear view: you’ll see a port for a sensor- wire
Motors designed for 1/8-scale
models often use 5mm shafts,
while motors destined for
1/10-scale and smaller cars have
SENSORED VS. SENSORLESS
Because they are equipped with sensors inside the motor
to register rotor position, “sensored” motors are generally more responsive at low rpm and provide more initial
torque than a comparable sensorless motor. Sensorless
systems rely on the motor spinning to communicate the
rotor’s position, so sometimes sensorless systems lag
a bit when accelerating from a stop or at low rpm. Both
sensored and sensorless systems work well, however,
and some users prefer the feel of one over the other.
Sensorless power systems generally cost a little less than
sensored systems of similar output.
When researching motor specs and features, rotor-shaft
diameter usually appears. Essentially, the larger the shaft
diameter, the more durable the rotor becomes. This is
especially relevant for high-rpm and large-scale motors,
where durability is more of a concern. One thing to keep
in mind regarding shaft diameter
is pinion gear selection. Since the
pinion attaches directly onto the
rotor shaft, it is important that you
select pinions that will fit your
motor. If you aren’t sure, simply
inquire at the hobby shop or online.
A “540” motor’s can is
approximately 540mm long.