In simple terms, a DSG automates two separate "manual" gearboxes (and clutches) contained within one housing and working as one unit.
[citation needed] By using two independent clutches,[2][4] a DSG can achieve faster shift times[2][4] and eliminates the torque converter of a conventional epicyclic automatic transmission.
[2] At the time of launch in 2003,[2][5] it became the world's first automated dual-clutch transmission in a series-production car,[2][5] in the German-market Volkswagen Golf Mk4 R32,[2][5] and shortly afterwards worldwide, in the original Audi TT 3.2.
For the first few years of production, this original DSG transmission was only available in transversely oriented[2] front-engine, front-wheel-drive and Haldex Traction-based four-wheel-drive vehicle layouts.
[13] Another notable change over the original transverse DSGs is the lubrication system[14][15] – Audi now utilise two totally separate oil circuits.
[13] This dual circuit lubrication is aimed at increasing overall reliability, due to eliminating cross-contamination of debris and wear particles.
[6] This was initially available in their quattro all-wheel-drive variants,[7] and is very similar to the new ZF Friedrichshafen-supplied[16] Porsche Doppel-Kupplung (PDK).
Whilst the motor vehicle is stationary and in neutral (N), the driver can select D for drive (after first pressing the foot brake pedal).
When the driver releases the brake pedal, the K2 clutch clamping force is increased, allowing the transmission to drive the wheels.
Depending on the vehicle speed and amount of engine power being requested by the driver (determined by the position of the throttle pedal), the DSG then up-shifts.
This sequence in a fraction of a second (aided by pre-selection), and can be performed without lifting off the throttle, resulting in minimal power loss.
[3] This is most apparent if the car is being driven at sedate speeds in one of the higher gears with a light throttle opening, and the accelerator pedal is then pressed down, engaging the kick-down function.
The seven-speed unit in the 2007 Audi variants will not automatically shift to 6th gear; rather, it stays at 5th to keep power available at a high RPM while cruising.
As an example, on the Volkswagen Golf Mk5 GTI, sixth gear will be engaged around 52 km/h (32 mph), when initially using the DSG transmission with the default ECU adaptation; although with an "aggressive" or "sporty" driving style, the adaptive shift pattern will increase the vehicle speed at which sixth gear engages.
This mode may not be ideal to use when wanting to drive in a sedate manner; nor when road conditions are very slippery, due to ice, snow or torrential rain – because loss of tire traction may be experienced (wheel spin during acceleration, and may also result in road wheel locking during downshifts at high engine rpms under closed throttle).
On 4motion or quattro-equipped vehicles this may be partially offset by the drivetrain maintaining full-time engagement of the rear differential in S mode, so power distribution under loss of front-wheel traction may be marginally improved.
When this plane is selected, the DSG can now be controlled like a manual gearbox, albeit only under a sequential shift pattern.
In most (VW) applications, the readout in the instrument display changes to 6 5 4 3 2 1, and just like the automatic modes, the currently used gear ratio is highlighted or emboldened.
[3] Current variants of the DSG will still downshift to the lowest possible gear ratio when the kick-down button is activated during full throttle whilst in manual mode.
However, these are now being offered (either as a standard inclusive fitment, or as a factory optional extra) on virtually all DSG-equipped cars, throughout all model ranges, including lesser power output applications, such as the 105 PS Volkswagen Golf Plus.
Alternatively, should the driver wish to immediately revert to fully automatic control, this can be done by activating and holding the + paddle[9] for at least two seconds.
The 7-speed DQ200 and 6-speed DQ250 gearboxes sometimes suffer from power-loss (gear disengaging) due to short-circuiting of wires caused by a build-up of sulphur in the transmission oil.
[35] Since 2009 there have been widespread concerns from Chinese consumers particularly among the online community, who expressed that Volkswagen has failed to respond to complaints about defects in its DSG-equipped vehicles.
[36][37] In a survey held by Gasgoo.com (China) of 2,937 industry experts and insiders, 83% of respondents believed that the carmaker should consider a full vehicle recall.
[40] The top five models that dominate those complaints were: Would be worth noting that Touareg has never been fitted with a DSG transmission.
On 17 March 2013 Volkswagen Group China announced on its official Weibo that it will voluntarily recall vehicles equipped with DSG boxes.
No official statement was released by the company, but it was stated that a total of 3,962 were involved in the unit recall exercise - units produced between June 2010 and June 2011, with affected vehicles being Golf, Polo, Scirocco, Cross Touran, Passat and Jetta models equipped with the transmission.