DSG 7-SPEED CLUTCH REPLACEMENT
When is an automatic gearbox not an automatic gearbox? When it is a Dual (or Twin) Clutch Transmission (DCT). While the gear lever might possess the familiar ‘P’, ‘R’, ‘N’ and ‘D’ gate, the hardware is not a traditional epicyclical geared/fluid flywheel torque convertor ‘auto’. Instead, the transmission contains parts associated more with manual gearboxes, which is why DCTs are not automatics in the technical sense but should be considered by the knowledgeable car owner as automated manuals. Their dry clutches, therefore, should be thought of as similar to those fitted to manual transmissions, even though the replacement procedure is very different.
While DCTs have a long heritage, they did not gain worldwide commercial acceptance, until adopted by the Volkswagen Group. The earliest mass production DCT used by the company was the six-speed DQ250, which the company christened Direct Shift Gearbox, or ‘DSG’. The DQ250 DSG6 provided a cost-effective, lightweight alternative to a conventional automatic transmission but was considerably more efficient. Drivers approved, because it sapped considerably less engine power than a traditional epicyclical-geared automatic and provided lightning-fast gear changes. As with conventional automatics, the DCT also offers high comfort and protection against driver misuse. Over revving, for example, is impossible. Owners also benefitted from reduced tax bills, owing to the reduced CO2 emissions. These early units employed ‘wet’ clutches, housed within the gearbox and cooled by the oil bath. While this made them last for a relatively long time, it placed the lubricant under additional stresses, meaning that mandatory periodic transmission oil changes are essential for ultimate longevity.
Being a pioneer of the modern DCT, improvements were never far away and Volkswagen introduced a new seven-speed transverse-mounted gearbox in 2008, which is this article’s focus. While marketing departments championed the additional ratio, a significant change was replacing the internal ‘wet’ clutch components with a sealed dry friction clutch assembly, mounted within the bellhousing. The new clutch pack enhances efficiency further, because energy is no longer wasted by churning the clutches against the resistance of an oil bath. Due to the lubricant being under less thermal stress, and not being exposed to contamination from friction linings, there was no need to equip the transmission with an oil cooler. Aside from reduced manufacturing costs, owners saved money by not conducting gearbox oil and filter changes at service time.
Yet, DCTs with dry clutch packs are coupled to less powerful engines. In the Volkswagen Group’s case, the dry clutched DQ200 seven-speed DSG can be found typically on 1.4-litre and non-turbo 2.0-litre SEATs, Skodas, Volkswagen and Audi petrols, plus 1.6-litre TDI and some lower-powered 2.0-litre TDI diesels. More powerful models, which produce more than 250 Newton Metres (Nm) of torque, tend to employ wet clutch DSGs.
ROB’S TOP TIP
References to DSG7,
