Alfa roméo Q2 (147 et GT)

[psal24]

Ca y est, il arrive le Q2 ! Il est disponible sur les Alfa 147 et GT en JTDm 150 ch uniquement mais devrait être étendu à la gamme Alfa.

[psal24]

Ces modèles ont droit à de petites touches de styles supplémentaires comme un spoiler arrière différent, rétros ton alu, échappement chromé, volant cuir surpiqué rouge, touches grises antracite à l'int, jantes 18" ... et un logo Q2 à l'arrière.

[psal24]

How the Alfa ‘Q2’ system works
The main element of the ‘Q2’ system is a limited slip differential, of the Torsen mechanical type. This differential splits torque between the front drive wheels dynamically and constantly, according to driving conditions and the road surface. Combined with the exclusive double wishbone front suspension, the system allows very effective fine tuning of the car.

Alfa Romeo started from the excellent reputation that front-wheel drive enjoys with customers (in fact it is the layout chosen by the majority of car-makers). Suffice it to say that, in addition to the overall benefits of this type of architecture (weight, roominess, etc.), in extreme conditions, the understeer typical of front-wheel drive enables the driver to respond more intuitively to the car’s reactions: this gives the impression that front-wheel drive is more ‘responsive’ than rear-wheel drive.

To highlight these benefits, Alfa Romeo has developed the ‘Q2’ system which embodies all the strengths of front-wheel drive, significantly increasing roadholding, traction and stability on the release, while attenuating understeer on acceleration, the intervention of the electronic control systems and steering wheel vibration.

The two practical examples below highlight the technical potential of the ‘Q2’ system.

Case no. 1: when the car corners
Taking a corner when grip is poor (wet road, snow, mud, etc.) or with a sporty driving style, grip is often 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 mounted. 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’.

What happens when the ‘Q2’ system is present
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 and maintains complete control of the vehicle.

Case no. 2: surfaces with poor grip
On surfaces with poor grip, it is quite common for the drive 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 could 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.

What happens when the ‘Q2’ system is present
The 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.

[psal24]

[psal24]

[flat-six]

le q2 est un différentiel à glissement limité? sur une traction?

[carlgan]

Ils auraient pu utiliser le visco drive... Il sert plus a rien non?

[vincent1600]

flat-six a dit : le q2 est un différentiel à glissement limité? sur une traction?

comme sur beaucoup de tractions puissantes (au meme titre qu'une propulsion ou une integrale, un torsen ou un autre dispositif est utile sur le ou les différentiels...

[mini team condroz]

Carlgan a dit : Ils auraient pu utiliser le visco drive... Il sert plus a rien non?

j'ai l'impression qu'un torsen est plus efficace.

[blast]

mouais... il arrive un peu tard le q2
dommage pour la 147 GTA !!! ah ces italiens ,j'ai du mal à les comprendre

[Lancia_Net]

Comment redynamiser une gamme vieillissante !

A+

[alpa38]

Ca me fait penser au diff Ranger des Maserati biturbo.
Le pb avec ce genre de truc à l'AV c'est que dans les virages ca resiste au volant. Donc la pompe de DA doit etre encore plus puissante et probablement à assistance variable. Bref des emmerdes en vue.
C'est vrai, pourquoi ne pas mettre le visco. On dirait Alfa->Lancia ca passe (le v6 par exemple), mais Lancia->Alfa jamais.