Inside ZF's nine-speed transaxle for 2013

AEI travels to Friedrichshafen for an exclusive look at the development and technology behind the 9HP-the industry's first nine-speed transaxle slated for MY2013 production.

With its 9.84 ratio spread, clever controls, and compact packaging, ZF's new nine-speed automatic transaxle will offer OEMs capability to increase fuel economy in their front-wheel-drive vehicles by 10-16% at 75 mph (121 kph), based on the NEDC cycle, when the gearbox is launched for MY2013 production next year.

Few new transmissions have caused as much buzz within the industry as the 9HP. ZF announced it at the 2011 Detroit auto show but provided almost no details of its inner workings. But this summer, ZF's top engineers gave a select group of media, including AEI, a look inside the 9HP and its development. The visit to the company's Friedrichshafen R&D center included a long test drive of three 9HP-equipped mules (see sidebar).