At one time, all four-wheel-drive systems were created equal. But not anymore.
Automakers are searching for technologies that can help separate their vehicles from the crowd. North American suppliers of 4wd systems are racing to develop new gadgets and features that keep those automakers happy - and keep themselves from becoming obsolete.
The majority of today's 4wd vehicles have traditional transfer cases. They are supplementary two-speed transmissions for distributing engine torque to the front and rear wheels. North America's main suppliers - New Venture Gear Inc. of Troy, Mich., and Borg-Warner Automotive's Powertrain Systems Corp., also in Troy - have racked up sales increases from their expanding use in recent years.
But transfer cases have too many limitations for the coming wave of passenger car-based sport-utilities.
The bulky units do not package well in vehicles based on front-wheel-drive platforms with transverse-mounted engines, such as the Honda CR-V. Borg-Warner predicts that class of vehicle will grow from one-fifth to more than half of 4wd vehicle sales by 2005.
Transfer cases also are expensive to make. Plus, the high- and low-gear modes that traditional transfer cases provide add cost. They also offer more off-road capability than many of today's truck buyers need.
'The transfer case business is approaching a commodity business, but we cannot be a commodity supplier,' said Robert Richardson, vice president of sales and marketing for Borg-Warner's Powertrain Systems Corp. The company supplies most of the 4wd transfer cases used by Ford Motor Co., as well as Mercedes-Benz U.S. International Inc. and Isuzu Motors Ltd.
Suppliers also are on the hot seat because margins are getting thinner on transfer cases. At the same time, the technology is becoming outdated.
Torque-on-demand, or fully automatic single-speed all-wheel-drive systems, 'are the perquisite for future products,' Richardson said.
European competitors such as GKN PLC and Steyr-Daimler-Puch AG are broaching the North American market with these products. Steyr, for example, has won a major contract to supply General Motors with awd systems for its new Pontiac Aztek and Buick Rendezvous minivan-based sport-utilities.
Instead of transfer cases, these systems use torque distribution devices, such as viscous couplings or electromechanical clutches, to distribute engine power among the axles and wheels.
In response, Borg-Warner has developed an awd system for car-based sport-utilities.
The technology, called the Interactive Torque Management System, uses electromechanical clutching devices small enough to fit into the rear-axle differential case. The cylindrical devices - one for each rear wheel - have metal balls, which, when excited by a magnetic field generated by an electric coil, roll up a circular ramp to lock the input and output shafts and transfer through the engine torque.
The system will go into production for the 2001 model year on a Japanese-brand vehicle. Richardson won't say which.
No extinction danger
Borg-Warner Automotive is the 23rd-largest supplier of original equipment parts to North America. It had $2.1 billion in global OE sales in 1998; about one-fourth of that comes from its Powertrain group.
New Venture Gear ranks No. 20 on the Automotive News list. CEO Fred Hubacker expects global OE sales to grow from $1.5 billion in 1998 to $2 billion this year.
While transfer cases are in no danger of extinction, Jim Lanzon, executive vice president of engineering for New Venture Gear, said the changing technology has spurred suppliers to scrap designs more quickly. 'We used to make the same cases for more than a decade,' he said. 'Now it can be as little as three years.'
New Venture Gear, a joint venture between DaimlerChrysler and GM, has spent millions on flexible machining equipment to replace its transfer lines. Flexible milling machines need only minor adjustments to accommodate a new transfer case design.
Like Borg-Warner, New Venture Gear also is scrambling to develop hardware that can give an OEM customer that sought-after claim of exclusivity. Two of New Venture's latest developments are under consideration by automakers but not yet scheduled for production.
They include a slope-sensing axle differential that can automatically lock or unlock as driving conditions change.
A locked differential sends engine torque equally to both wheels on the axle but provides no engine braking on downhill descents, because its overrunning clutch only locks in one direction. This feature uses an electronically activated bidirectional clutch that can lock or run freely in either direction. It makes off-road driving easier, as it locks the axle differential to the driveshaft when engine braking is needed for steep descents.
The company also has developed a shift-on-the-fly high- to low-range 4wd. Currently, most transfer cases do not allow shifting from 4wd high range to 4wd low unless the vehicle is stopped. However, a synchronizer added by New Venture Gear allows push-button shifting up to 10 mph.
A small improvement, but one that would give an automaker an exclusive feature not offered by others. Being able to provide those choices gives a supplier an advantage, said Borg-Warner's Richardson.
'Exclusivity is something the entire 4wd supply base is after,' he said.