Figure 8: Audi-VW DSG
Together with a dual-mass flywheel, the twin multi-disk wet clutch is known to be perfectly smooth and it can mimic the creep provided by a torque converter. In D or S (S standing for "sport") position, the operation is quite similar to that of a conventional automatic transmission. But the driver is also offered a sequential mode controlled by two paddles behind the steering wheel, or alternatively by the central console shifter just as on the Tiptronic and Multitronic. Racing launches are possible, thanks to the well cooled outer multi-disk clutch and to the powertrain's electronic regulation: simultaneously hammer down on both the accelerator and brake pedals and then release the brakes. On downshifts, the engine is automatically accelerated to the matching revs by the ECU, supposedly to avoid unnecessary clutch slippage.
In view to get a compact and short unit, it is designed on a 3 shafts layout, just like the basic manual 6-speed O2 M 350 from which it was developed from. On the Golf R32 both manual and optional DSG transmissions encompass the same ratios as well as several common parts. Due to its more elaborate construction and automatic control system, the DSG brings an extra weight of 30 kg for a total of 90 kg. The twin clutches are concentric and electro-hydraulically activated, controlled by a "Mechatronic module" placed on the transmission's casing. The signals coming from 10 individual sensors are centralized there and the data for actuation are calculated according to the actual driving conditions recorded by the CAN bus. The pressure applied to the clutches and the position of the synchro-sliders-sleeves units are managed according to the situation by shift-valves and slider-valves controlled by solenoids. Electronics also work out which gear is to be pre-selected and manages the oil circuit via 6 automatically controlled governors and 5 on/off valves. It remains to be checked if the pre-selected gear always corresponds to the driver's desires!
It is possible to downshift from 6th into 2nd in 0.9 second, the transmission shifting first to 5th then to 2nd. Of course the shift from an even ratio to an odd or conversely is done without delay after pre-selection.
The oiling circuit comprises an oil cooler. The average fuel consumption, given to 9.8 l/100km, is slightly reduced compared to a manual cogbox while it is strongly diminished compared to a conventional automatic torque converter transmission. The maximum speed of the Audi TT V6 is limited to 250 km/h. The Golf R32 can reach 247 km/h and the optionally DSG equipped sprints from 0 to 100 km/h in 6.4 seconds, faster than the manual version which needs 6.6 seconds.