Detroit's high-tech route to a smoother, safer ride

Drivers used to the soft, ``living room'' ride of the typical American luxury car may find themselves in for a shock later this year if they take a ride in the new Lincoln Continental. The flagship of the Ford Motor Company's luxury division, the Continental is going through some radical changes for the 1988 model year. But the most visible change, the car's newly restyled, aerodynamic shape, hides a far more significant engineering development: one of the most advanced suspension systems ever used on a production car, luxury or otherwise.

Dubbed ``adaptive ride control,'' it relies on a microcomputer ``to adapt to driver and road inputs,'' said Ray Nicosia, a Ford product developer.

Translation: A series of sensors located near each wheel and in the steering wheel help determine such things as the roughness of the road surface, and when a driver makes a fast or emergency turn.

The computer responds by sending commands to special shock absorbers, each of which can independently stiffen or soften the car's ride. The microprocessor also regulates special air bags, which replace conventional wheel springs. These can, for example, make an immediate correction, keeping a car level if a heavy load in the trunk shifts from one side to the other. These calculations and corrections occur in no more than 40 microseconds - the time it takes a car traveling 60 miles an hour to move about 8 feet.

In a test ride along a rough mountain road north of Vancouver, Mr. Nicosia demonstrated how the adaptive ride control system can comfortably ``float'' over all but the roughest washboard roads, just like a typical American luxury car.

But moments later, as the car entered a sharp curve, he yanked the wheel hard to the left, the type of maneuver that would have sent the 1987 Continental virtually out of control. Instead, the computer quickly responded by stiffening the outer shocks, yielding a slightly rougher ride, but only the faintest tire squeal as the car easily stayed within its lane.

In essence, Ford officials insist, adaptive ride control allows them to combine the tighter handling of European sports luxury sedans with the more comfortable ride of old-fashioned American luxury cars.

Ford is not the only company singing the praises of electronically controlled suspensions. Less sophisticated systems are already in use on a number of Japanese vehicles, such as the Mazda 626 sedan.

And a number of carmakers, including Ford, Honda, and General Motors, are already working on more advanced systems, dubbed ``active suspensions,'' in which shocks, springs, and air bags/shocks are completely eliminated by hydraulically controlled ``actuators.'' These can be so precisely regulated they hold the car tightly to the road, or softened to make even the harshest bumps ``invisible.''

Active suspension ``is probably not as significant as the development of the wheel,'' said Fred Schaafsma, chief engineer of GM's Chevrolet Division, ``but it is certainly the most significant development since we put suspensions on cars.''

Though he declined to provide much detail, Mr. Schaafsma noted that a fully active suspension system is likely to be in the next generation of the Chevrolet Corvette, which debuts in the 1991 model year.

Developed by General Motors' British racing subsidiary, a prototype of that system is already in the public eye, helping Brazilian sports car racer Ayrton Senna make a commanding presence this year on the international Formula One Grand Prix circuit.

As a result of the active suspension on his 1,300-horsepower, Team Camel-Honda-Lotus race car, ``you give less physically to drive,'' Mr. Senna said following his June victory in the Detroit Grand Prix.

But it is not only the driver that is less abused by the rigors of 180-mile-per-hour straightaways and sudden, sharp turns. As a result of active suspension, wear and tear on the car appears to be greatly reduced. As evidence, Senna ran the Detroit race on one set of tires, virtually unheard of in Grand Prix driving, and something that may have cut up to 30 seconds off his time.

``An active suspension can give you exact wheel-positioning, and therefore less wear,'' said Michael Kimberley, chief executive officer of Group Lotus, a GM subsidiary that is affiliated with the Lotus racing team.

Though Chevy appears committed to equipping Corvette with an active suspension system, not everyone is convinced that is the best solution. Some engineers believe a less sophisticated ``semiactive'' design, such as on the Lincoln Continental, will eventually become the industry standard.

At the core of the debate is the issue of cost. According to some sources, active suspension could add at least $5,000 to the price of a limited-production sports car, such as the Corvette, though Mr. Kimberley says the price could drop to ``$1,200-$1,300'' on cars produced in volumes of more than 200,000 units. That would still be far more expensive than semiactive systems.

But what most automotive engineers do agree on is that by the end of the century, in one variation or another, electronically controlled suspension systems are likely to become as common as computer-operated fuel injection is today.