Dual-Clutch Transition

In less than a decade, automakers have gone from four-speed automatic transmis-sions to seven- and eight-speed units.

In less than a decade, automakers have gone from four-speed automatic transmis-sions to seven- and eight-speed units. Though the latter are usually found in an OEM’s most expensive offerings—if at all, they’re still fairly rare outside of Mercedes and Lexus—but soon will be making their appearance outside of the ultra-luxury segment.

Volkswagen, which introduced its six-speed DSG in 2003, has announced plans to launch its transverse DQ200 seven-speed DSG in the 2008 model year. Though not strictly an automatic—it is basically two manual gearboxes (1,3,5,7 and 2,4,6,R) with a pair of clutches that swaps gears automatically or at the driver’s command via paddles behind the steering wheel. However, the transmission’s primary control is the standard floor-mounted P-R-N-D-S shift quadrant used by most automatics. What makes the DQ200 unique—beyond its seventh speed—is its small size. Measuring just 14.5-in. in length and weighing 174 lb., including the dual-mass flywheel, the gearbox can be used in everything from the B-Class Polo to the D-Class Passat, and is capable of handling engines up to 168 hp and 184 lb-ft of torque.

VW engineers used the opportunity to lower first gear for better acceleration from stand-still, and raise seventh to increase highway fuel economy and lower noise. In addition the volume of oil in the gearbox has been reduced by 75%, in part from the replace-ment of the six-speed DSG’s wet clutches with dry clutches. The oil circuit is split with one side cooling and lubricating the gear teeth, and the other feeding oil to the gear actuators. This gearbox will be used with VW’s small diesels, as well as its Twin-charger (supercharged and turbocharged) and sub-2.0-liter direct injection gasoline engines.

BMW, on the other hand, will add a Getrag (Untergruppenbach, German; www.getrag.de) dual-clutch transmission to the 2008 M3 V8. This gearbox will replace the current auto-mated manual SMG transmission; a trans-mission that is known for its recalcitrance in all but hard road or track driving. A Getrag official who requested anonymity described it as: “Best suited for small in-town delivery vehicles.” It’s a tough assessment, especially considering Getrag supplies the SMG gearboxes to BMW for the current M5.

The seven-speed transmission will be sold alongside a conventional manual gearbox under the M-DCT name, and variants will migrate to the rest of the 3 and 5 Series lineups over a two-year period. Getrag also is developing its DCT technology for Chrysler, for use with the Phoenix V6 engine, and Ford of Europe. (GM also is planning to use DCTs, though it is unclear who will supply them at this time.) With Congress rewriting the CAFE standards, some powertrain experts at the domestic car makers are expecting use of this technology to double the 7% North American market share originally expected by 2015.—CAS