Spektrum SPMS651 S651 7Kg Steel Gear Servo

The Spektrum S651 is a standard-size waterproof steering servo built with a steel and brass gear train. It is the updated version of the ADS-7M servo and serves as a direct replacement for the factory-installed servo in a range of ARRMA 3S BLX vehicles.

The steel and brass gear set replaces the plastic gears found in entry-level servos, giving the S651 meaningfully better mechanical strength and longevity under the shock loads that come with bashing and off-road running. The case is fully waterproof, so the servo holds up to wet grass, puddles, mud, and snow without needing to be sealed or relocated. Together those two features make it a sensible replacement when a stock servo has stripped or taken on water.

Torque is rated at 88 oz-in (6.37 kg-cm) at 6.0V and 103 oz-in (7.42 kg-cm) at 7.4V. Transit speed is 0.143 sec/60 degrees at 6.0V and 0.122 sec/60 degrees at 7.4V. The servo measures 1.58 in (40mm) long, 0.79 in (20mm) wide, and 1.55 in (39.4mm) tall, matching the standard servo footprint for broad chassis compatibility, and uses a 23-tooth output spline.

ARRMA fitment includes the Big Rock 3S BLX, Granite 3S BLX, Senton 3S BLX, Typhon 3S BLX, and Vendetta 3S BLX. The package includes one servo, four grommets, and mounting hardware.