When you have changed the ring and pinion gears in your differential, the speedometer will no longer read the correct speed. This unit electrically corrects the speedometer reading to compensate for the new gear ratio. Easy installation. Please choose your gear ratio below. Speedometer Calibration Box corrects speedometer reading to compensate for new ratio of changed out differential gears.
Unitrax Speedometer Calibration Box, 92-02 Vipers