AYC (Active Yaw Control)
Evolution VII retains the Active Yaw Control traction enhancement system that has fully proven its worth since its introduction in Evolution IV in 1996. AYC uses an electronically controlled hydraulically actuated system to optimally control yaw moment in the body by regulating torque split in the rear differential to create a torque differential in the right and left rear wheels. This allows the vehicle to better trace the line chosen by the driver through corners, spreads tire load more evenly and also improves standing start and acceleration over slippery surfaces. In Evolution VII, integrated control of the ACD and AYC systems realizes a dramatic improvement in the balance between stearing response and traction in high G cornering.

Mitsubishi's Active Yaw Control traction enhancement system uses a computer to optimally regulate torque transfer in the rear differential on 4WD models and thereby tailor rear wheel differentials to match driver operation and vehicle operating status. In this way, MMC's proprietary system both equalizes the load on the four tires by adaptively regulating the yaw moment that acts on the body and improves cornering performance without inducing any sense of deceleration. When accelerating through a corner, AYC reduces understeer by transferring torque to the outer wheel; when decelerating in a corner, AYC enhances stability by transferring torque to the inner wheel. AYC also improves traction on surfaces with low or split friction coefficients and has fully proven its worth since it was first introduced in Evolution IV. For Evolution VII, all parts of the torque transfer mechanism of rear differential have been uprated to match the increase in engine torque, while breather and clutch operating durability have been improved. The system shares the same computer, hydraulic actuator unit and sensors as the ACD, thus reducing weight and improving reliability.


ACD (Active Centre Differential)
Evolution 7 features a new Active Center Differential using an electronically controlled variable multi-plate clutch. The ACD boasts a differential limiting capacity three times greater than that of the viscous coupling-type differential used to date. In addition, the ACD's ability to tailor slippage for different driving conditions brings levels of steering response and traction control not possible with a viscous coupling differential. A 3-way manual override switch enables the driver to select Tarmac, Gravel or Snow modes to suit his preferences or conditions. The ACD also frees the differential on operation of the parking brake - thereby enabling the driver to make more effective use of side brake turns in rallies and other events.

This system regulates differential limiting force to match driver operation of his vehicle and driving conditions. Developed with the motor sports arena firmly in mind, the ACD uses a center differential to distribute drive torque equally between front and rear wheels and thereby improve steering response at the same time as enhancing traction - a vital factor in reducing stage and other race times. Ensuring optimal transmission of drive torque from the engine to the road surface under all conditions, ACD's multi-plate clutch delivers up to three times the differential limiting force of a viscous coupling-Mode ACD modes type unit. To achieve this level of performance, the multi-plate clutch employs the same kind of steel plates as mechanical limited-slip differentials, thereby offering superior durability and response under high clutch plate load conditions. Using sensors, the system electronically optimizes the cover clamp load to match driver input and vehicle operating status. Thus able to regulate center differential limiting action from free to locked, as conditions require, the ACD realizes the ideal 4WD system. Under hard acceleration, the ACD reduces slippage and approaches a locked state, thereby transmitting more torque to the road surface for better traction and acceleration. When the driver makes rapid steering inputs, meanwhile, the ACD operates virtually as an open differential to improve steering response and feel through corners while retaining outstanding 4WD stability. The ACD also enables the driver to manually select one of three modes - Tarmac, Gravel, Snow - giving optimum traction for paved, un-paved and snow-covered roads according to preference or to suit conditions. And, for the rigors of rally, gymkhana or other competitive use, the ACD operates in a virtually open state when the parking brake is used, thereby enabling rapid and effective side brake turns.

From Mitsubishi marketing material.





diagram of how it works together