Driving With AWC Ralliart/EVOs- Do You Ever Change It ??

[ijustatecurry]

This article seems quite good

"Active Center Differential (ACD)

The heart of any four-wheel drive system is the means of power distribution, which is a key to establishing the vehicle’s handling behavior. First employed on the Japanese-market Evolution VII model, Mitsubishi’s Active Center Differential (ACD) made its North American debut in the previous-generation Lancer Evolution models. (The track-handling capability of that model was only recently eclipsed by the new-generation Lancer Evolution with Super All-Wheel Control system featuring both ACD and the Active Yaw Control torque-vectoring rear differential.)

The ACD splits torque up to 50:50 between the front and rear wheels using an electronically controlled hydraulic multi-plate clutch. The All-Wheel Control computer optimizes ACD clutch cover clamp load for different driving conditions, regulating the differential limiting action between a free state (where torque is split equally between front and rear wheels) and a locked state to optimize the torque split and thereby produce the best balance between traction and steering response.

The maximum limited-slip torque of the ACD multi-plate clutch is about three times that of a conventional viscous coupling. The hydraulic unit housed in the engine compartment regulates the hydraulic pressure of the multi-plate clutch within the range of zero to 145 PSI.

The All-Wheel Control computer takes data input from various sensors to continuously calculate the ACD ‘s limited-slip torque. Steering wheel angle, throttle opening, wheel speeds, and the vehicle’s longitudinal and lateral movements are constantly measured to determine the vehicle’s path of travel. Using this data, the AWC computer determines whether limited-slip torque should be increased or decreased at any given time.

As in the Lancer Evolution, the Lancer Ralliart offers three driver-selectable traction modes for the ACD, changeable while the car is moving using a switch on the dash: “Tarmac” for dry, paved surfaces; “Gravel” for wet or rough surfaces, and “Snow” for snow-covered surfaces.

In each mode, the ACD adjusts center differential locking behavior to suit the road conditions. The car’s other dynamic handling systems respond to the road conditions and driver input. The multi-information monitor, located between the tachometer and speedometer, displays the selected ACD mode and also provide status indicators for ACD operation."

[bobcrusader]

Yeah, but testing it by doing fast U-Turns is more fun than reading about it

[lamn8tr]

Ha ha Rob. I'm still a bit scared to really push my car sideways. I have tried in the past on a wet road with the Tarmac mode selected and all other safety features still on...and yes it's nearly impossible to get it sideways.

So if the diff locks later in Gravel mode and everyone uses it on a wet road, won't this allow the car to get more sideways and therefore be more dangerous in a loss of traction scenario ?? Tarmac mode seems the safest for wet and sealed roads right??

[El-Diablo]

With traction control off I can four wheel slide in tarmac mode in the dry, gravel seems more a rear drive split

[billy boy]

don't be afraid to speak up - there are others who want to hear your stories it's all in the name of getting a better understanding of how the RA handles on the limit to increase our knowledge base and to limit the amount of 'surprises' when they occur

[shamrockshirts]

Interesting that you're experiencing different characteristics than most other owners. Must be a logical reason. Anything different on your car? Sway bars? Different rubber from back to front maybe?

[shamrockshirts]

If I'm reading this right you're discribing "liftoff oversteer"

Definately not what I'm experiencing as anytime I've been sideways I'm WOT aiming for the apex and its all oversteer.

I can get slight oversteer with ASC off and Tarmac ON but its a whole different ball game in Gravel mode and ASC off.

Maybe just different driving styles?

[bongo]

I've had it on tarmac since I bought it.

[El-Diablo]

definitely agree with shamrock. Gravel is rear wheel bias, tarmac is 4 wheel balanced, snow is front wheel biased.

Having worked in the car industry front wheel drive tends to be the preferred method in snow environments.