YPSILANTI, Mich. - General Motors has shifted into high gear with plans to introduce a continuously variable transmission.
The automaker will offer a small car with a continuously variable transmission for the 2002 model year, said Harvey Won, engineering director for transmissions at GM's Powertrain division. The transmission likely will be assembled in Europe.
At least two automakers, Honda Motor Co. and Nissan Motor Co. Ltd., have introduced CVTs. Ford Motor Co., Fiat Auto S.p.A. and DaimlerChrysler plan to introduce continuously variable transmissions in the next few years.
Ford formed a joint venture with ZF Friedrichshafen AG to produce up to 1 million CVTs annually for Ford and non-Ford vehicles by 2005. The venture will begin producing CVTs in a former Ford plant in Batavia, Ohio, in the second half of 2001, about the same time as GM.
GM plans to build about 100,000 of the new transmissions annually starting in the 2002 model year, said Mark Gunderson, GM Powertrain's engineering group manager for continuously variable transmissions. About 310,000 continuously variable transmissions were built worldwide in 1998, according to the AutoFacts Group of PricewaterhouseCoopers LLC in West Chester, Pa.
A continuously variable transmission varies the speed ratio between the engine and the wheels using pullies and a belt. Hydraulic pressure forces the two halves of the transmission's V-shaped pullies to squeeze together or pull back, causing the steel belt to ride higher or lower on each pulley.
The transmission delivers better fuel economy and is potentially cheaper to build than a conventional automatic. However, those attributes could be lost on American drivers accustomed to cheap fuel and large vehicles.
Gunderson acknowledges that continuously variable transmissions have durability problems when bolted to big engines. GM's design can handle 148 pounds-feet of torque, about the same output as the base 2.2-liter four-cylinder engine in the 2000 Saturn LS. But the company expects most sales will be in Asia and Latin America, where it could replace manual transmissions.
'As cheap as our gas is here, the customer base for a CVT is very questionable,' said Steve Acker-man, director of base transmission hardware for GM Powertrain.
GM's continuously variable transmission for front-wheel-drive vehicles offers 7 percent better fuel economy than a comparable GM four-speed automatic transaxle, said Gunderson.
The design also requires about half the number of parts as GM's automatics, which typically contain about 550 parts.
The steel band, supplied by Van Doorne Transmissie BV of the Netherlands, is the most expensive part in the CVT, Gunderson said.