Active Yaw Control

The AYC was introduced for the first time in the Lancer EVO IV in the 1996, it's function is absolutely ingenious it is made of an electronic and mechanical part, the potenziality of this electronic device was immediately clear. It includes a very simple but efficient technology, the Mitsubishi factory used a similar system on the WRC which brought to victory, many times, the rally champion, Mr. Tommi Mäkinen.

This electronic differential allows to keep the bend in perfect trajectory. I tested the difference personally, when this system comes into function, it is like an "increasing of grip" and the bend is driven in a natural way. First, select the trajectory that you want to follow, hold tightly the steering wheel, push down the accelerator pedal (in the middle of the bend) and if you are not at the fisic limits, your EVO will follow perfectly the trajectory you wanted. if you exaggerate, the AYC will give you a hand, and you will only have to correct the skid.

AYC is composed of two parts, electronic and electrohydraulic.

Electronic section:

- longitudinal acceleration sensor

- front and rear lateral acceleration sensor

- angle sensor steering wheel

- wheels rotational speed sensor

- throttle opening sensor

- ECU

Mechanic section:

- multiplate clutch with electrohydraulic actuator

Photo of AYC orizzontal section

The parts which build up the electronic differential

The AYC transfers, the torque on the external or internal wheel according to the over or understeering. The advantages do not finish on the help to complete the trajectory, as would do an LSD (Limited Slip Differential) but also on braking, thanks to AYC which gives a hand to maintain the stability of the car.

The torque shifts on the rear left axel

The torque shifts on the rear right axel

Super AYC

Mitsubishi developed a new system for rear differential. On EVO VIII was installed Super AYC which includes interesting news. It functions in the same way as its predecessor but the new rear differential determines twice the torque to the rear wheels by switching from the use of a bevel gear to a planetary gear differential. This twice torque increases the limit of cornering of 10%.

A beautifull picture of Super AYC orizzontal section

Block diagram of ACD+AYC systems