Some more info to help/confuse me
I guess the book may not say much but would like to find out, although i will prob find out my self at the end of Sept
1,600 Nm maximum locking moment. If the control module detects wheel slip at one of the front wheels, the plates are actuated to redistribute the drive torque from the wheel with the lower grip level to the wheel with the higher level. The maximum locking moment is 1,600 Nm, so that if necessary all of the drive torque can be directed to just one front wheel; that corresponds to a locking value of 100 per cent. This produces maximum traction for a front-wheel drive vehicle, even under difficult roadway conditions and in turning situations.
ESC Sport
In the new Golf GTI, Volkswagen is offering the "ESC Sport" function for very experienced drivers. The system is activated by a two-stage switch on the centre console. If the driver pushes the button once briefly, it deactivates the ASR function (traction control). When the button is pressed longer than three seconds, Electronic Stability Control (ESC) switches to the "ESC Sport" mode. In very fast driving with lots of bends - such as on a race course - the ESC system reacts with a delay, which enables even greater agile handling properties. As an alternative to activation by the pushbutton on the centre console, ESC can now also be activated or deactivated by settings in the CAR menu.
[Source: Volkswagen]
Unlike the electronic EDL or XDS traction systems, which use a standard differential in conjunction with individual electronic control of the front brakes, the VAQ is an active mechanical clutch pack-based device located between the differential cage and the right-hand drive shaft. The pressure required to actuate the clutch pack is produced and regulated by an electrically-powered hydraulic pump
The car has a normal differential in the gearbox casing.
So, we have a system of variable "friction" clutches, modulated by hydraulic pressure from an electric pump, that can modify the "locking" action (the Slip) between one of the halfshafts and the crownwheel / diffcage. (exactly as in a conventional LSD)
In a turn, the different wheel paths result in a wheel speed variance, and the lateral G results in a tyre normal load difference. As such, for a conventional differential, which MUST maintain the same torque for both wheels (set by the lowest denominator), if the driver applies a drive torque higher than that set by the inside wheel (the lightly normally loaded one) that wheel will overspeed, resulting in that excess torque simply being used to speed up that wheel/tyre and not to drive the car forward.
With a locked diff, the limit becomes that of the outside wheel/tyre, which will be significantly higher due to the weight transfer onto that outside tyre (latG x CofG height x front mass). This means the car can longitudinally accelerate harder than one without an LSD.
With the locking system, the diff will act to EQUALISE the speed differential across the front axle, and as a result the inside wheel will overspeed. However, this will not result in a high longitudunal acceleration (assuming the tyre is full loaded and is at the "peak" of its slip/force curve). In fact, this will result in less longitudinal drive force on the inside wheel. However, the outside tyre can accept this higher drive torque, and produce a high longitudinal drive force, and as such the inside wheel drive force falls and the outside one rises. This is the "effective" Torque Vectoring that they are talking about.
It does however rely on the driver applying more throttle, and hence more drive torque, themselves (unlike a proper torque vectoring system that can do this with the torque it is currently supplied with). The result of that is probably what Dan is talking about as a "slighty none intuitive" need to apply more throttle that seems normal to get the front diff to really "work" in his Gti/Meganne piece
The biggest benefit of the electronic control of slip is that your input parameter matrix become very wide indeed. For a conventional LSD using ramps or sprung plates etc the input parameter is primarily drive torque (both positive (drive) and negative (overun). With electronic control, you can apply modifications to the wheel speed split (and hence vehicle yaw authority) based on things such as vehicle speed, driving mode (Normal, sport, eco etc) and of course multiple inputs from the dynamic stability control system (for example, keeping an open diff with no handwheel feel corruption most times, but locking it hard when yaw stability (and phase lag) become critical, such as in an emergency lane change etc
[Source: Max Torque]
