Almost 18 months ago, at the International VDI Conference “Transmissions in Vehicles 2011″, ZF announced the world’s first 9-speed transmission for passenger cars. ZF are hoping their latest transmission will signal the end of the cog swapping race, with CEO Stefan Sommer saying 9-speed is the “natural limit”.
We doubt this is the case though, as progress is unstoppable and Hyundai has already proclaimed it’s been working on a 10-speed gearbox. Ford and General Motors have also mentioned that they’d be happy to work together to develop 9- and 10-speed transmissions.
In Mr. Sommer’s words, “There is no hard line, but you have to consider the law of diminishing returns. The question is whether adding even more gears makes sense”. Julio Caspari, head of ZF in North America, has also hinted that the race to add gears may be driven more by marketing and a perception among buyers that “more is better”. Caspari told Automotive News that, in terms of efficiency, ZF’s current 8-speed transmission is separated from “theoretical perfection” by a margin of just 11 percent.
In 2009, ZF began manufacturing its 8-speed transmission for cars and light commercial vehicles. ZF says that compared to a 6-speed transmission it provides 11 percent improved fuel economy. In 2013 the company’s new 9-speed, 9HP, transmission will enter production, which will bring a further 5 percent increase in fuel efficiency compared to the 8-speed unit.
ZF says the 9HP automatic gearbox will handle between 270 Nm and 480 Nm of torque and, thanks to the extremely high total spread of 9.84, the gearbox allows the engine to run in the most fuel-efficient speed range. For example, in 9th gear and travelling at 120 km/h, the engine will be turning over at just 1 900 r/min, compared to 2 600 r/min in a 6-speed automatic.
The 9HP transmission is expected to begin appearing in new models sometime in 2014, with Honda and its luxury sub-brand Acura rumoured to be among the first to feature the new ‘box. Chrysler is also expected to manufacture the new 9HP transmission under license in the U.S. for its new front-wheel-drive models.
