1/18 Scale 155mm Wheelbase Assembled 4WD RC Chassis with 2-Speed Gearbox & Wheels

Specifications

• Scale: 1/18 Scale
• Wheelbase: 155mm
• Drive System: Full-Time 4-Wheel Drive (4WD)
• Transmission: Mechanical 2-Speed Dual-Ratio Gearbox (Shift Servo Included)
• Chassis Frame Material: Reinforced Composite Polymer and Metal Spars
• Suspension: Independent / Multi-Link Articulated Suspension with Threaded Shock Mounts
• Wheel / Tire Diameter: 55mm Off-Road Treaded Rubber Tires
• Motor Mount: Standard Micro RC Motor Mounting Block 
  
• Shift Servo Compatibility: Standard 9g / Micro Servo PWM signal (3.3V – 6V)
  
• Recommended Battery Voltage: 7.4V (2S LiPo) or 6.0V NiMH Pack

Minimum hardware 

• 2S 7.4V LiPo Battery or 6V-7.4V Battery Pack  required to supply sufficient current for both the drive motor and mechanical shift servo under load.
• Brushed ESC (Electronic Speed Controller, 20A+)  required to regulate motor speed and direction via standard PWM signals.
• RC Transmitter & Receiver (Minimum 3-Channel)  required to control steering (CH1), throttle (CH2), and the 2-speed gearbox shift servo (CH3).
• Micro Steering Servo  required to steer the front axle knuckles via the pre-assembled steering linkage.

Safety & Handling Warnings

• Servo Operating Voltage: Ensure your receiver's BEC (Battery Eliminator Circuit) outputs between 4.8V and 6.0V DC. Supplying more than 6.0V directly to micro shift servos without a regulator will burn out the internal servo driver.
• Gear Shift Procedure: Do not actuate the 2-speed gearbox shift servo while the main drive motor is running at full throttle. Always shift gear ratios at low throttle or zero RPM to prevent stripping the internal transmission gears.
• Battery Polarity: Always double-check power wiring polarity on your ESC before connecting the battery pack. Reverse polarity will destroy the speed controller instantly.

Accessories Included in the Box

• 1× Pre-Assembled 1/18 Scale 155mm 4WD RC Crawler Chassis
• 4× Mounted Off-Road Rubber Tires with Internal Foam Inserts
• 1× Integrated Dual-Speed Mechanical Transmission Gearbox
• 1× Installed Micro Gear Shift Servo with Linkage

Frequently Asked Questions

• Is the 1/18 assembled chassis compatible with standard 1/18 scale RC crawler bodies?
  Yes, the 155mm wheelbase fits most standard 1/18 scale hard-plastic and polycarbonate body shells, including popular micro crawler body mounts.
• Can I control the 2-speed shift servo using an Arduino or ESP32 microcontroller?
  Yes, the onboard shift servo accepts standard 50Hz PWM signals, making it fully compatible with microcontrollers and custom autonomous control boards.
• What type of motor fits onto the integrated gearbox motor mount?
  The mounting plate is designed to accept standard micro RC brushed motor sizes, including 180 and 370 class micro motors.
• Can I use a 3S LiPo battery with this chassis?
  While the mechanical frame can physically hold small packs, 3S voltage depends entirely on your ESC and motor rating; 2S (7.4V) is strongly recommended for transmission longevity.

• What is the recommended operating voltage for the electronics on this chassis?
  The chassis hardware is optimized for standard 6.0V to 7.4V DC setups powered by a 2S LiPo battery pack.

• How much voltage can the shift servo handle safely?
  The included micro shift servo operates safely between 4.8V and 6.0V DC, supplied by your ESC's internal BEC circuit.

• Does the chassis include an integrated battery tray?
  Yes. The chassis features an integrated center-lowering battery strapcompartment sized for compact 2S Mini LiPo packs.
• How do I connect the 2-speed shift servo to an RC receiver?
  Plug the 3-pin servo connector into Receiver Channel 3 (CH3) or any auxiliary channel mapped to a 2-position switch on your radio transmitter.
• Do I need to calibrate the shift servo travel endpoints?
  Yes. Adjusting the endpoint travel (EPA) on your transmitter is crucial so the servo shifts completely into gear without straining or stalling against the mechanical stops.
• Why is the 2-speed gearbox making a grinding noise during shifting?
  Grinding usually occurs when shifting under full throttle. Always ease off the motor throttle slightly during the gear transition.
• Why is the shift servo overheating or buzzing continuously?
  Continuous buzzing indicates that the servo endpoint travel is set too far, causing the servo motor to stall against the mechanical limits of the shift rod.
• Why does one wheel lift off the ground under heavy acceleration?
  This is natural torque twist inherent to 4WD shaft-driven crawlers. Adjusting the shock spring preload, particularly on the rear-right corner, can help neutralize this effect.