1997 NSX/NSX-T Chassis
6/30/1996 8:21:51 PM
Outstanding handling characteristics have been a hallmark of the NSX and NSX- T since their inception. For 1997, key chassis refinements have been made to complement the performance enhancements that have been engineered into the car.
Larger brakes have been added, and the Anti-Lock Braking System (ABS) has been refined to handle the increased horsepower of the larger engine. The NSX's revolutionary variable electric power-assisted steering system. In addition, the forged alloy wheels now feature a bright, machined finish for 1997.
The desired goals for the NSX suspension went well beyond the typical goals of high lateral adhesion, transient response and linear response to control input. The engineers wanted a suspension that allowed the driver to easily control the car right to the limit, particularly with the more powerful 3.2-liter V-6 engine.
The basic configuration is similar to that of a Formula One car in that it employs an upper and lower control arm (or double-wishbone) design with a coil-over shock absorber and stabilizer bar front and rear. The rear suspension also has an additional transverse link for greater wheel control. All the suspension arms are made of extremely rigid and durable forged aluminum. The front steering and the rear hub carriers are also made from heat-treated aluminum castings. The springs are straight rate with an extended rubber bump stop mounted on the chassis which acts as a progressive springing element at the limit of wheel travel.
The shock absorbers are nitrogen-filled and feature a unique progressive valve design. The progressive opening of this valve produces a more favorable damping profile, and more precise damping control, than a conventional valve system in which the fluid control orifices are either fully opened or closed.
The front and rear suspension components are mounted on separate aluminum subframes using rubber bushings, designed to reduce vibration yet limit flex and shift of the suspension components relative to the subframes.
The suspension development program was far-ranging and took place at the Tochigi Proving Grounds, the Suzuka circuit, the 179-turn Nurburgring course in Germany, the Honda Proving Center of California (HPCC), and Honda's newest test track in Takasu, Hokkaido. In addition to the standard evaluations conducted in-house by the suspension engineers, the car was subjected to evaluation by top-rank drivers such as the late, three-time Formula One World Champion Ayrton Senna, Indianapolis 500 winner Bobby Rahal, and Formula One driver Satoru Nakajima.
The NSX is equipped with 4-wheel ventilated disc brakes and dual-piston steel calipers. The diameter of the front and rear discs has increased for 1997: from 282 mm front and rear to 298 mm in the front and 303 mm in the rear. To accommodate the larger discs, new calipers have also been fitted. Combined with new piston sizes, a better braking balance has been achieved. The braking targets were to set new levels of braking performance, and to . provide excellent pedal feel, linear braking response and low pedal effort. Splash guards with cutouts aid in air ventilation and enhance fade resistance.
Four-Channel Anti-Lock Braking System (ABS)
The enhanced, 4-channel Anti-Lock Braking System controls each wheel independently with a 16-bit microprocessor. This 4-wheel independent capability allows fine control of the anti-lock function especially when the car is braking on a surface with a split coefficient of friction-for instance, if the left side wheels are on snow, ice or standing water and the right side wheels are on dry pavement.
The basic configuration uses independent parallel hydraulic circuits. In addition to the primary, non-anti-Iock braking circuit, the anti-lock system has its own hydraulic reservoir, pump, modulator unit, solenoids and control pistons. If a failure in the anti-lock hydraulic circuit should occur, normal braking force will be fully retained by the primary braking circuit.
Variable Electric Power-Assisted Steering System
This power-assisted steering system was the first of its kind on the American market, and is significantly improved in the areas of inertial feel and steering stability for 1997 due to the refinements in the ECD that controls power assist. The system consists of a rack-and-pinion steering gear with an electric motor installed concentrically around the steering rack. The steering system is a direct design which functions with no assist at higher vehicle speeds. A speed sensor in the electronic control unit determines road speed and, coupled with a new torque sensing system, feeds a signal to the motor. To ensure reliability, the electrical system for this unit features gold-plated connectors. All NSX models feature this electric power-assisted steering system.
Forged Alloy Wheels
To reduce unsprung weight, and provide the highest strength possible, the engineers specified forged-aluminum alloy wheels. To enhance the look of the wheels, they have been machine finished, then clear-coated. The result is a very light wheel with the strength and impact resistance of a much heavier steel wheel. The rear wheels are 8.5 x 17 inches, and the front wheels are 7 x16 inches.
The suspension engineers, working in conjunction with Yokohama Tire Company and Bridgestone Tire Company, sought to produce tires that would not only provide excellent traction and handling, but also allow the driver to "feel" the limits of the tires' performance.
The resulting uniquely designed tires were remarkable, meeting all the high-performance targets the engineers established early in the program.
The NSX is equipped with wide, low-aspect-ratio tires, front and rear, for more responsive handling and increased cornering capability. The tire sizes are 215/45 ZR16 front and 245/40 ZR17 rear. These tires provide excellent wet- and dry-weather traction, high-speed stability and immediate and predictable reaction to steering input.