Turning At All Corners

The market for 4-wheel steering systems, such as Delphi Corp.'s Quadra-steer, is expected to grow at a compounded rate of 50% a year until 2006, the supplier predicts.

The market for rear steering on big pickups and SUVs didn't exist two years ago, so any growth is bound to be statistically significant. Still, four solid years of growth is hard to ignore. Delphi is the biggest player in the segment, for now.

TRW Automotive doesn't want to let Delphi monopolize the market. The Cleveland-based supplier first produced 4-wheel steering in March 2000 for medium-duty commercial vehicles in Europe.

TRW, in partnership with American Axle & Mfg., has developed electric rear steering for light vehicles and has several prototypes, including a Cadillac Escalade, says Aly Badawy, TRW's vice president of Steering, Suspension and Integrated Vehicle Controls.

Japanese auto makers used rear steering more than 20 years ago to improve maneuverability for cars in congested cities. Honda Motor Co. Ltd. even sold its Prelude coupe in the U.S. beginning in 1988 with rear-wheel steering, but the option was discontinued here due to low take rates.

For colossal pickups and SUVs, however, the technology is ideal. When the driver turns the front wheels left, the rear wheels go right (thanks to sensors and an electric steering motor), allowing the back end to come around more quickly. There's no steering shaft — it's all by-wire. Delphi's Quadra-steer shrinks the turning circle on the GMC Sierra pickup from 47.3 feet (14.4 m) to a Saturn-ish 37.4 feet (11.4 m). No more struggling to dock the Suburban at the Chuck E. Cheese parking lot.

General Motors Corp. is the biggest champion of rear-steer. But if Ford Motor Co. and the Chrysler Group don't buy in soon for their own SUVs and pickups, the segment could be in peril.

It's easy for consumers to like Quadrasteer, but GM hasn't done Delphi any favors in marketing it. It's an expensive option priced up to $6,000. Until volumes rise, the feature remains a luxury for well-heeled buyers of $45,000 work trucks.

Plus, it's hard to tell how much Quadrasteer costs because GM has it packaged with trailer kits and certain axles, engines and seats. It debuted on '02 Sierra Denali and remains standard for '03; for '03, Quadrasteer is offered on Chevy Silverado and Suburban and GMC Sierra 1500HD and Yukon XL 3/4-ton SUVs.

The next advancement for 4-wheel steering will move beyond maneuverability to improved stability control. Current generation “open loop” systems function irrespective of vehicle dynamics. But TRW and Delphi are developing “closed loop” rear-steer systems that interact with the vehicle's brakes and a yaw sensor to detect oversteer. So a vehicle equipped with stability management can have an extra level of control with the addition of rear-steer.

Larry Tomczak, Delphi's business line director of electric steering, says auto makers recognize the tremendous benefits of integrating rear-steer in stability control systems. “We have customers already looking at closed-loop Quadrasteer,” he says.

For example, Tomczak says a passing semi-trailer can make a car sway because of wind. “This system detects it and corrects it before the driver even knows it,” he says.

Badawy isn't saying whether TRW will beat Delphi to market with a closed-loop system. “I think there's room in the market for us and them,” he says.

GM will produce its next-generation fullsize pickup in 2006, and American Axle will supply the axles. If any models offer rear-steer or independent rear suspension, American Axle will be the integrator, says Daniel Sagady, American Axle vice president of engineering.