User's Manual

Tachometer Sensor
The tachometer (“tach”) sensor is used to monitor the rotation speed of a vehicle component such as a
drive shaft and this speed is converted into vehicle speed.
You will need to measure the distance your model rolls in order to provide the React with enough
information to give you an accurate speed. We recommend that you get a tape measure and measure
several rotations of the wheel to reduce the measurement error.
Installation
1. Choose the mounting location
In the drive train, after any clutch or transmission. We recommend that you do not try to mount the
magnets on your motor for magnetic reasons (electric motors) and balance reasons (nitro motors).
Smaller diameter mounting points are better.
The tach sensor must be able to be mounted within 1-2mm of the magnet surface, so you’ll need a solid
mounting point that can position the sensor in the right place.
The completed installation should be rigid enough that proximity is maintained without the magnets
impacting the sensor.
2. Install the magnets
Stick two magnets together, mark the exposed faces, then separate them.
Install the magnets with the marked sides out, exactly 180º apart to preserve rotational balance.
IMPORTANT: For correct operation, the sensor must see alternating north and south magnetic poles.
Ideally, countersink the magnets into the surface.
3. Install the tach sensor