Alfa Romeo’s Q2 system embodies all the strengths of front-wheel drive, while significantly increasing roadholding, traction and stability on the over-run and attenuating understeer on acceleration, delaying the intervention of the electronic control systems, and reducing steering wheel vibration.
Two practical examples below highlight the technical potential of the Q2 system
Taking a corner when grip is poor (wet road, snow, mud, etc.) or with a sporty driving style, grip can be lost on the inside wheel. When the transfer of the lateral load takes weight off the suspension, torque on the inside wheel is reduced, and a conventional differential (which splits the same torque value between both wheels) transfers an equal amount of torque to the outside wheel, but this is insufficient for good traction.
In this situation the car can respond in two different ways, depending on the equipment fitted. On a model without ASR-VDC, the perceived result is the slipping of the inside wheel, a loss of control of the car (strong understeer) and a loss of acceleration coming out of the bend. If, on the other hand, the car is equipped with ASR-VDC, the intervention of the driving assistance systems takes power from the engine, acting on the throttle valve and the braking system, so that it becomes impossible to modulate the accelerator, producing the unpleasant sensation of a drop in power.
In both cases, the result is that as the car comes out of the bend, the driver has the feeling that it is ‘stationary’.
And with the Q2 system in place?
When the inside wheel starts to lose grip, torque is partially transferred to the outside wheel, producing less understeer, greater stability, and increasing cornering speed.
The improved mechanical efficiency of the Q2 transmission delays the intervention of the vehicle control systems, guaranteeing better traction as the car exits the bend, which makes driving more enjoyable while maintaining complete control of the vehicle.
Surfaces with poor grip
On surfaces with poor grip, it is quite common for the driven wheels to have different degrees of grip. For example, grip under the two wheels can differ on snow-covered or wet roads.
In these conditions, starting off or accelerating sharply can cause the wheels to slip, generating critical friction conditions, a strong reaction on the steering wheel, and inadequate take-off, making it necessary to correct the steering wheel continuously to maintain the trajectory.
And with the Q2 system present?
These negative effects are attenuated by the gradual transfer of torque to the wheel that can exploit the best friction coefficient, simplifying a hill start, for example, and making driving on all roads with changing surface conditions safer and more comfortable.Published 23 October 2007