Description
The Speedhut Speedbox without Mechanical Cable (A-299) is an advanced solution for retrofitting cable-driven mechanical speedometers with modern digital accuracy. This compact unit supports both GPS and Vehicle Speed Sensor (VSS) signals, allowing it to interface effortlessly with newer transmissions that lack mechanical speedometer outputs. With only a 12-volt power and ground connection required, installation is quick and hassle-free. The included GPS antenna enables automatic calibration without the need for tedious setup procedures or subscription services. Compatible with most US speedometers through its standard 7/8″-18 threaded output and 0.112″ square drive, the Speedbox maintains classic instrument aesthetics while delivering precise, modern performance.
KEY FEATURES AND BENEFITS:
- GPS and VSS Compatibility: Accepts speed input from GPS or Vehicle Speed Sensor sources for greater installation flexibility.
- Plug-and-Play Installation: Requires only a 12-volt power and ground connection to operate.
- No Calibration Required with GPS: Automatically calibrates when GPS antenna is used—no manual programming needed.
- Classic Speedometer Integration: Supports mechanical speedometers via 7/8″-18 thread and 0.112″ square drive.
- Broad Calibration Range: Adjustable from 170 to 1650 turns per mile, accommodating a wide range of speedometers.
- Maintains OEM Aesthetics: Enables the continued use of factory mechanical gauges with modern drivetrains.
- Included GPS Antenna: Ensures accurate, real-time speed data without requiring a subscription.
- Dashboard Mountable: Compact design allows for discrete installation within the dashboard area.
SPECIFICATIONS:
- SKU: A-299
- Drive Output Thread: 7/8″-18
- Drive Output Square: 0.112″
- Calibration Range: 170–1650 turns per mile
- Default Calibration: 1000 turns per mile (US speedometers)
- Power Requirement: 12 volts and ground
- Included: Speedhut Speedbox unit, GPS Antenna, Power Harness
HOW TO USE:
- Connect Power: Wire the red lead from the power harness to a 12-volt power source.
- Connect Ground: Wire the black lead to a proper ground point on the chassis.
- Attach GPS Antenna: Mount the GPS antenna where it has a clear sky view and plug it into the Speedbox.
- Mount the Speedbox: Place the unit securely inside the vehicle dashboard.
- Connect Mechanical Cable: Attach a compatible mechanical speedometer cable (not included) to the threaded drive output.
- Start the Vehicle: Turn on the ignition. The Speedbox will automatically calibrate if GPS is used. If using VSS, follow calibration instructions as needed.
BENEFITS OF USING THE SPEEDHUT SPEEDBOX WITHOUT MECHANICAL CABLE (A-299):
- Modern Compatibility: Allows older speedometers to work with new transmission systems lacking mechanical outputs.
- GPS-Based Accuracy: Provides a reliable speed signal even if the original VSS is faulty or unavailable.
- Easy Installation: Minimal wiring required—just power and ground.
- Automatic GPS Calibration: No user intervention needed when GPS is used, saving setup time.
- Wide Speedometer Support: Works with most mechanical speedometers using adjustable turn-per-mile calibration.
- Retain Classic Look: Continue using original speedometers while enjoying modern signal processing.
- Reduces Cable Hassles: Eliminates issues tied to outdated or damaged mechanical cables (though a new cable is needed).
FEATURES:
- Accepts GPS and VSS speed input signals.
- 7/8″-18 threaded mechanical drive output with 0.112″ square shaft.
- Calibrates for speedometers from 170 to 1650 turns per mile.
- Pre-set to 1000 turns per mile for most US models.
- Installs with only 12V power and ground wiring.
- Automatic GPS calibration—no manual setup required.
- Designed for installation inside dashboard compartments.
- Subscription-free GPS operation.





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