Important Safety Information
Read the ENTIRE instruction manual to become familiar with the features of the product before operating. Failure to operate the product correctly can result in damage to the product, personal property and cause serious injury. This is a sophisticated hobby product. It must be operated with caution and common sense and requires some basic mechanical ability. Failure to operate this product in a safe and responsible manner could result in injury or damage to the product or other property. This product is not intended for use by children. Do not use with incompatible components or alter this product in any way outside of the instructions provided by Horizon Hobby, LLC. This manual contains instructions for safety, operation and maintenance. It is essential to read and follow all the instructions and warnings in the manual, prior to assembly, setup or use, in order to operate correctly and avoid damage or serious injury.
Product Overview
The ARRMA BLX3668 2400Kv 4 Pole 4S Brushless Motor (ARA390265) is designed to provide high speed and torque for remote control vehicles. It is optimized for use with the ARRMA BLX120 ESC unit.
Key Features:
- Beautifully etched black aluminum motor can for a premium look.
- 4-pole internal configuration ensures smooth and consistent power delivery.
- Gold bullet connectors for fast and easy wire removal.
- Finned body section on the aluminum motor can for increased heat dissipation.
- 2400Kv rating for balanced speed and torque.
- Designed for 4S LiPo battery compatibility.

Image: The ARRMA BLX3668 2400Kv 4 Pole 4S Brushless Motor, showcasing its black aluminum can and gold bullet connectors.
Specifications
| Motor Type | Brushless |
| Motor Kv | 2400 |
| Poles | 4 Pole |
| Motor Length | 68mm / 2.68" |
| Diameter | 36mm / 1.42" |
| Shaft Length | 18.5mm / 0.73" |
| Shaft Diameter | 5mm / 0.2" |
| Motor Mounting Hole Diameter | M3 |
| Motor Cable Length (Including Connector) | 45mm / 1.77" |
| Motor Connector Diameter | 4mm / 0.16" |
| Motor Weight | 228g / 8.04 oz |
| Recommended ESC | ARRMA BLX120 ESC (AR390264) |
| Recommended Battery | 4S LiPo |
What's in the Box
The product package includes the following:
- 1 x ARRMA BLX3668 2400Kv 4 Pole 4S Brushless Motor (ARA390265)
Setup and Installation
Proper installation is crucial for optimal performance and longevity of your brushless motor. Always ensure your vehicle's power system components are compatible.
1. Mounting the Motor:
- Ensure the motor mount in your vehicle is clean and free of debris.
- Align the motor's mounting holes with those on the motor mount. The BLX3668 motor uses M3 mounting holes.
- Secure the motor using appropriate M3 screws. Do not overtighten, as this can damage the motor casing or mount.
- Adjust the motor position to achieve the correct gear mesh between the pinion gear and the spur gear. A small amount of play is necessary; too tight will cause excessive wear and heat, too loose will strip gears.
2. Wiring Connections:
- Connect the three motor wires to your Electronic Speed Controller (ESC) using the 4mm gold bullet connectors.
- The BLX3668 motor is designed for use with the ARRMA BLX120 ESC (AR390264). Ensure your ESC is rated for 4S LiPo operation and can handle the motor's current draw.
- While brushless motors do not have a strict polarity for the three phase wires, connecting them in a specific order will determine the motor's rotation direction. If the motor spins in the wrong direction, swap any two of the three motor wires.
- Ensure all connections are secure and insulated to prevent short circuits.
3. Pinion Gear Selection:
Selecting the correct pinion gear is vital for balancing speed, torque, and motor temperature. Refer to your vehicle's manual for recommended gearing options. Monitor motor temperature during initial runs; if the motor is excessively hot, consider using a smaller pinion gear.
Operating Guidelines
Adhere to these guidelines for safe and efficient operation of your ARRMA BLX3668 motor.
- Battery Compatibility: This motor is designed for 4S LiPo batteries. Using batteries with higher voltage can damage the motor and ESC. Always use batteries that are in good condition and properly charged.
- ESC Settings: Configure your ESC according to its instruction manual and the motor's requirements. Pay attention to settings such as timing, punch control, and low voltage cutoff.
- Temperature Monitoring: Regularly check the motor's temperature during operation. Excessive heat (above 160°F / 71°C) can lead to permanent damage. Adjust gearing or driving style if overheating occurs.
- Environmental Conditions: Avoid operating the motor in excessively wet or dusty conditions unless the vehicle and motor are specifically designed and sealed for such environments.
- Break-in: Brushless motors generally do not require a break-in period like brushed motors. However, it is good practice to perform a few gentle runs to ensure all components are functioning correctly before aggressive driving.
Maintenance
Regular maintenance will extend the life and performance of your BLX3668 brushless motor.
- Cleaning: After each use, especially in dirty conditions, clean the motor exterior with a soft brush or compressed air to remove dirt and debris. Ensure cooling fins are clear for optimal heat dissipation.
- Inspection: Periodically inspect the motor for any signs of damage, such as bent shaft, loose wires, or cracked casing. Check the bullet connectors for corrosion or wear.
- Bearings: The motor's internal bearings are sealed, but extreme conditions can affect them. If you notice increased noise or resistance, the bearings may need inspection or replacement by a qualified technician.
- Wire Connections: Ensure all wire connections remain secure. Loose connections can cause intermittent power, arcing, and damage to components.
Troubleshooting
This section addresses common issues you might encounter with your brushless motor.
| Problem | Possible Cause | Solution |
|---|---|---|
|
|
|
|
|
|
|
|
|
Warranty and Support
ARRMA products are manufactured to high standards. For warranty information, technical support, or replacement parts, please contact ARRMA customer service or visit the official ARRMA website. Keep your proof of purchase for any warranty claims.
Official ARRMA Website: www.arrma-rc.com





