In yesterday’s installment of Trans Wars we explored the benefits and downsides of conventional automatic gearboxes, ones that feature fluid-filled torque converters. This type of transmission has been around for more than 50 years; it works well and has pretty much become the industry standard.
SEE ALSO: Trans Wars Episode I: The Phantom Pedal
But this configuration is being challenged by a sporty new rival. This cheeky up-and-comer promises improved fuel economy and blindingly fast gear changes. Join us for Trans Wars Episode II: Attack of the Clutches.
“The primary advantage to the [VW] DSG, the dual-clutch transmission, is the efficiency of the transmission,” said Doug Skorupski, powertrain strategy manager at Volkswagen of America. He noted that torque converters are where most of the efficiency is lost in a conventional automatic.
“The speed at which the transmission changes gears is an advantage as well,” he said, noting that dual-clutch models are well-suited to performance-oriented cars. “[It’s] a more fun-to-drive transmission,” which is why VW has made it available in vehicles like the GTI hatchback and GLI sedan.
But that’s not all. Because of the added efficiency the company also offers its DSG in several thrifty, diesel-powered TDI models.
Curiously Volkswagen’s DSG, which is short for Direct Shift Gearbox, was completely developed by the automaker. Skorupski said it was “designed and built in house underneath the VW brand.” This is kind of rare these days; automakers often purchase advanced technology from outside companies.
“A characteristic of the dual-clutch transmission is that it is still basically a manual transmission,” noted Skorupski, adding, “You still have clutches that engage and disengage.” Because of this, he said dual-clutch transmissions are generally not as smooth as conventional automatics at low speeds.
To help ameliorate this issue, VW engineers opted to go with a wet-clutch configuration. This arrangement is slightly less efficient than one that features dry clutches but it’s much more refined.
For instance, competing transmissions from Ford and Chrysler feature dry clutches and they have received complaints about shift quality. Ford’s PowerShift gearbox offered in the Fiesta and Focus small cars is particularly irksome.
Skorupski said engineers have tried to “maximize the comfort of the [DSG] transmission.” They considered a dry-clutch arrangement but he said, “The disadvantage to it is such that we didn’t feel that it was appropriate here in the U.S.”
But with every rule there’s an exception. Volkswagen does in fact offer a DSG with dry clutches and it’s found in the Jetta Hybrid.
According to Skorupski the company has made great strides improving their dual-clutch transmission over the years in order to make it as smooth as a conventional automatic. “Each year we continue to make refinements,” he said.
Where appropriate, Volkswagen still offers conventional torque-converter automatics. Cars like the Jetta and Passat feature them. However, there is a transmission technology they are not pursuing. “We don’t have any CVTs in our products today,” Skorupski said.
Continuously variable transmissions are not necessarily a cutting-edge innovation, but they are relatively new to the market and do offer some alluring benefits.
SEE ALSO: Should You Buy a Car with a CVT?
Like what you see? Well, don’t miss tomorrow’s installment of this ongoing series. Trans Wars Episode III: Revenge of the Shift will go live in the morning hours so make sure to check it out. You know you want to…