Audi has unveiled a new version of its TT Coupé sports car with a 3.2-litre V6 engine and innovative automated manual transmission. It goes on sale in mid-2003.
The so-called Direct Shift Gearbox (DSG) transmission combines a conventional six-speed manual gearbox with selectable automatic operation.
The basis is a six-speed manual gearbox with high variability in the selection of the transmission ratio. An integrated twin multi-plate clutch with control system allows two gears to be engaged at the same time. When the car is driven, one gear is engaged and when the next gearshift point is approached, the appropriate gear is preselected but its clutch kept disengaged.
The gearshift process opens the clutch of the activated gear and closes the other clutch at the same time. The gear change takes place under load, with the result that a permanent flow of power is maintained.
The technology of this twin-clutch transmission, claimed to be the only one of its kind in the world, has its roots in motor racing.
The new transmission has been developed at VAG group level, is built at the Kassel transmissions plant and is capable of handling torque of up to 350 newton-metres.
The control logic integrated into the transmission casing maintains optimum gearshift patterns that perform lightning-fast gearshifts that are claimed to be nevertheless smooth and almost jolt-free.
The driver can directly influence the gear selected and the gearshift timing at will, by means of the gear lever in the manual gate or the standard-fit shift paddles on the steering wheel.
In the automatic mode, the driver can shift from position D to the sporty S programme, in which upshifts are retarded, downshifts advanced and the shifting process accelerated. A remote one-touch function accessed via the shift paddles on the steering wheel in addition temporarily calls up the manual mode even in automatic modes D and S.
As on conventional manual gearboxes, the transmission ratios are present on input and auxiliary shafts in the form of pairs of toothed wheels. In contrast to manual gearboxes, the input shaft is divided into two sections. It comprises an outer hollow shaft, and an inner shaft. The first, third, fifth gears and reverse are located on the inner shaft. The hollow shaft handles the even-numbered gears.
Each of these shafts is selected by means of a separate multi-plate clutch running in oil. The two electronically controlled, hydraulically actuated clutches are packed inside each other for maximum space economy.
As well as their high efficiency and ability to transmit high torques, clutches of this type permit a wide range of starting characteristics. In other words, the multi-plate clutch can be controlled in such a way that every conceivable form of pulling away is possible, from an ultra-gentle edging along on a slippery surface to sports-style acceleration at full throttle.
A shift-by-wire control concept has been implemented. The mechatronic concept combines a control unit with an electro-hydraulic control unit. The device is housed in the upper section of the transmission casing and processes signals from 10 individual sensors, calculating the actuation values calculated using the relevant information on the current driving situation from the drive CAN bus.
The application pressure of the two clutches is regulated by special solenoid-operated valves depending on the situation, and the gear positioners operated.
The electronics also calculate which additional gear is to be preselected by the corresponding positioning cylinder and selector forks, and manages all actuating elements and the oil cooling circuit via six pressure regulation valves and five on/off valves.
Audi claims its new concept results in a decidedly agile performance, with the added benefit of the typically low fuel consumption of an advanced six-speed manual gearbox.
VAG’s proven 3.2-litre V6 engine, seen in sports versions of the Golf, powers the new TT variant.
In this installation, the engine now delivers 184 kW (250 bhp) and a broad peak-torque range peaking at 320 Nm from 2,800 to 3,200 rpm.
The Audi TT 3.2 accelerates from 0 to 100 km/h in 6.4 seconds, and the top speed is governed to 250 km/h. Overall consumption is 9.8 litres/100 km comparable to similar vehicles with a six-speed manual gearbox.
Brakes use a 17-inch dual-piston system adapted from the version used on the RS 4. There are floating callipers with ventilated 334 millimetre brake discs at the front while the rear wheels have 265 millimetre ventilated discs.
The new top-of-the-range TT version is distinguished by a modified rear spoiler and a rear apron with enlarged inlet openings and lateral gills.
The front apron now incorporates larger openings to cover the higher demand for cooling air, without affecting aerodynamics.
The TT 3.2 quattro also has xenon head lights as standard with range control and titanium-coloured headlight trims. Inside, as well as the shift paddles on the steering wheel this version has a gearbox gate in polished aluminium.