The Haldex controller is an essential device for every competitor using a car equipped with a Haldex (first generation) 4Motion system in drag racing. Our Haldex controller provides an option for complete engagement during start and automatic disengagement above a user selected speed. A huge advantage is the fact that it does not require any additional sensors, which allows for the 4Motion system to be used in cars without ABS. The device can be successfully used in everyday cars, where rear drive engage can be seamlessly adjusted with a potentiometer.