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FIRMA 3900Kv 4-pole BL Motor



*at participating retailers

FIRMA 3900Kv 4-pole BL Motor

Item #: SPMXSM3300


Retail: $105.99*

Find a Retailer Buy Now *Avaliable at participating retailers


Product Specifications

1/10 Scale Brushless Surface Motor
RPM/Volt (Kv):
Continuous Current:
Overall Diameter:
1.4" (36 mm)
Shaft Diameter:
0.2" (5 mm)
Overall Length:
2.35" (60 mm)



Great choice for 1/10 Scale 4WD models looking for a high RPM motor upgrade running up to 3S * (12.6v) power. Low cog 4-pole rotor design, CNC machined aluminum housing, insulated high purity copper windings, high-quality alloy steel 5mm output shaft, and high-precision bearings for high durability and smooth rotation. Preinstalled with 4mm gold plated bullet connectors for easy installation. Perfectly matched for the Firma 130 Smart ESC.

*Will work with the 85A Firma ESC, but only for 2S power.


• Perfect upgrade for brushed 540- and 550-size brushed motors with the same diameter and mounting pattern (vehicle must accept pinions with a 5mm bore)
• High-quality 4-pole sintered rotors
• Includes 4mm gold plated bullet connectors
• Precision ball bearings and hardened steel 5mm shaft
• SafeD-5 Pinion compatible

In The Box

(1) Spektrum Firma 3660-3900kv Sensorless 1/10 Brushless Motor with 4mm Gold Plated Bullet Connectors
(1) Product Manual

Manuals and Support

Related Parts

Optional Accessories  See All

  • Firma 85 Amp Brushless Smart ESC 2S - 3S[SPMXSE1085]

  • Firma 100 Amp Brushless Smart ESC 2S - 3S[SPMXSE1100]

  • Firma 120 Amp Brushless Smart ESC 3S - 4S[SPMXSE1120]

  • Firma 130 Amp Brushless Smart ESC 2S - 4S[SPMXSE1130]