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Just 'Cuz Robotics

JCR-4935 1000kV Battle Hardened Brushless Motor

JCR-4935 1000kV Battle Hardened Brushless Motor

Regular price $90.00
Regular price $0.00 Sale price $90.00
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Built For Combat From the Ground Up!

Now in stock and shipping immediately!

Months of work have gone into making the most durable motor possible to fit into a beetleweight (or even bigger) combat robot, and this is the result. In larger weight class bots there are many modifications frequently made to motors to help them survive the rigors of combat. Boring out the motor to fit larger bearings, larger more durable shafts, removing circlips and set screws, and adding epoxy to the magnets all to battle harden these motors. Now for the first time ever, you can buy a motor off the shelf with all of these changes and more! Download the JCR-4935 CAD here, plus Subtraction's blade and shock mount designs here

The JCR-4935 was designed with combat in mind from the ground up - this is not some hodgepodge of parts from different motors and separate machined components, it's a proper motor, tightly integrated and professionally balanced. You can improve durability further with our custom shoulder bolts and clever blade mounting!

What's Included when you buy a Complete Motor:

1X JCR-4935 motor, combat-ready out of the box!
6X Alloy Steel M5 x 12mm flat head screws
4X Alloy Steel M5 x 10mm button head screws
4X 6mm diameter x 10mm length hardened steel dowel pins (these will be a slip fit with the top of the motor, and must press fit into blades or whatever else you are attaching on top).
This motor is intended to be mounted to a rigid robot frame component and as such does not come with a mounting plate or bracket. 

What's Included when you buy a Replacement Magnet Ring:

1X JCR-4935 1000kV magnet ring, already epoxy battle-hardened and balanced!



  • Dimensions: 49mm can diameter, 35.5mm can length
  • Stator Size: Roughly 40 x 12mm (About 70% larger than 3536 can motors)
  • Weight: 213 grams (7.5 oz, 0.47 lb)
  • KV: 1000kV (More options may be available in the future)
  • Voltage: 3S-6S with appropriate ESCs
  • Power and Current: See the below chart for empirical test data
  • 6X M5 bolts for mounting to your robot frame, 4X M3 on 25mm circle as alternative 'compatibility' mounting
  • 4X M5 bolts and 4X 6mm dowel pin holes to attach weapons, gears, pulleys, or whatever else you can think of
  • 4140 Alloy steel 8mm billet flanged shaft, hardened to 46-48HRC
  • No circlips or set screws!
  • Super strong, curved neodymium magnets
  • Epoxied magnets for extra durability
  • High-temperature copper windings, 14AWG silicone wires rated to 200 C
  • Large 698 and 688 bearings to support the shaft, M5 button head bottom shaft attachment
  • Winding Resistance: measured 86.5 milliOhms

3D Model Available Now!

Experimental Bench Test Data (Using Pariah 70A ESC)

Power and ESCs

For best results, pair with our very own Pariah 70A ESC with AM32 firmware and pre-programmed for this very motor!

The specs are not precisely known due to this being a custom motor, but you should use a 50A or greater rated ESC. This has been tested and working with 70A BlHeli32 and AM32 ESCs, 45A Tekko45, and a few others. More testing is still in the works.

Actual current draw and torque are highly dependent on your exact ESC and configuration, battery, voltage, and loading. Air resistance and tip speed for your weapon play a huge role in the current draw of your system. Even reducing speed by 20% might cut air resistance in half. 


Warning: combat robots are not toys! They are extremely dangerous. Click here for a safety video.

Testing a robot with an active spinning weapon should never be done while maintaining a line of sight with the robot. Ideally, you should be testing inside an enclosed box or arena with at least 1/4" thick polycarbonate windows or top to see through, and 1/2” or thicker plywood or MDF construction. Operation (Including testing) outside of a suitable arena or test box could cause serious injury. By purchasing this product you acknowledge that you are responsible for the safe use of this product and that Team Just ‘Cuz Robotics or its employees are not liable for any injuries or damages.

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