Spektrum SPMXSM2100 Firma 3668 2400Kv Brushless Motor

The Spektrum SPMXSM2100 Firma 3668 is a 2400Kv 4-pole sensorless brushless motor built for 1/10 scale vehicles, including the ARRMA Kraton 4S 1/10 and Outcast 4S 1/10.

The 4-pole design is the key characteristic. Compared with a 2-pole motor of similar size, a 4-pole layout produces more torque at lower RPM, which suits heavy 1/10 scale bashers that need to accelerate hard out of corners and pull through loose surfaces rather than simply reach a high top speed on smooth ground. At 2400Kv running on 2S through 4S, it covers a wide usable power range depending on the pack fitted.

Being sensorless keeps the installation simple, with no sensor wire to route, damage, or contaminate with dirt and moisture, which is a practical advantage on a vehicle that gets run hard and washed often.

Specifications are a 68mm length and 36mm diameter, a weight of 288g, a 19.25mm shaft length with 5mm shaft diameter, 45mm wire leads, and 4mm bullet connectors for the ESC. The 5mm shaft accepts standard 5mm bore pinion gears.

This works both as a direct replacement where it was fitted as original equipment and as a power upgrade for a 1/10 vehicle moving up in capability. One brushless motor is included.