HEADLINES

1990 Acura Integra - Chassis

Design Objectives

In designing the new Integra's chassis, the goals were: a high degree of linear stability, precise and quick transient response, a favorable front/rear balance for neutral handling, substantial stopping power, and a smooth and comfortable ride.

To achieve these ends, the new Integras have a fully independent, double-wishbone suspension system, a new speed-sensitive variable-assist power rack-and-pinion steering system, and larger 4-wheel disc brakes. In addition, fine tuning of suspension geometry and spring rates, and a new type of shock absorber valve provide exceptional handling and ride quality.

Suspension

- Double-Wishbone Front Suspension -

This type of suspension has been proven in the Acura Legend automobiles. Its sophisticated design is compact, efficient and has excellent ride and handling characteristics, with outstanding on-center feel, quick turn-in and flat cornering.

The upper and lower control arms are widely separated for better load dispersion and provide improved anti-dive control while braking or accelerating. The geometry is arranged to permit minimum camber change for more precise wheel control to make handling more sure and predictable.

The basic layout of a double-wishbone front suspension uses two arms, or wishbones, of different lengths. This arrangement creates a small positive steering offset, minimizes changes in track and camber, and improves anti-dive characteristics.

The main components of the Integra's front suspension are an upper lateral arm, a lower trailing compliance link and a lower lateral arm. The lateral arms control the vertical motion of the wheel. This permits nearly vertical spring and damper travel and relieves the spring/shock unit from any wheel locating functions, which reduces shock friction and improves ride. A front stabilizer bar contributes to flat cornering.

- Front Shock Absorbers -

The Integra's gas-pressurized front shock absorbers feature new developments by Showa. Each shock absorber incorPorates a teflon, rather than steel, piston ring for near-perfect sealing. This allows the use of a unique second valve for more precise damper control than is possible with conventional, single valve, shock absorbers, both under compression or tension. This new design keeps damping force constant, decreases friction, improves durability and reduces cylinder wear.

The new damper is particularly effective at low shock absorber piston speeds, a condition which occurs when turning into a comer or during lane-change, or slalom-type maneuvers. With the new shock absorber exerting a more linear damping force, steering is more responsive and initial body roll is counteracted. With the shock absorber playing a greater part in these areas, it was possible to use a lower spring rate so that ride comfort was maintained without compromising handling.

- Double-Wishbone Rear Suspension -

The Integra's rear suspension is a refined design that provides both precise wheel control and, because it is very compact, more useable luggage space. The rear suspension is located by pivoting lower compliance trailing arms, lower lateral arms, and upper lateral arms, which pivot in front of the shock absorber and spring unit.

An innovative feature of this system is a compensating link pivoted at the front of the trailing arm. It cancels undesirable toe-change to help keep the rear wheels parallel, thus maintaining stability, particularly during braking and over rough surfaces. It also permits more compliance than would otherwise be possible, which results in a better ride with no unfavorable effect on handling.

Rear suspension geometry also incorporates a built-in camber change to improve cornering power and reduce rear-body lift during braking. Gas pressurized shock absorbers provide rear damping and a tubular stabilizer bar controls body roll.

Steering

Road feel is an integral element of superior handling. This is the feedback the driver receives from the steering wheel and it can easily be masked by power assistance. The Integra has a new steering system which controls assistance according to vehicle speed so that road feel is maintained.

Sensors in the system monitor speed and it adjusts itself automatically to provide maximum assistance at very low speeds, as when parking or driving in city traffic. As speed rises, power assistance decreases at a linear rate, reaching its lowest level around 35 mph. The transition is so smooth that the driver is not aware of the change and the force required to steer the car remains fairly constant. A high degree of road feel is maintained under all driving conditions.

Brakes

Power-assisted 4-wheel disc brakes are a standard feature of all Acura automobiles. In the new Integra, the size of the ventilated front discs has been increased to 262 rom (10.3 in.). The solid rear discs are 239 rom (9.4 in.) in diameter. Power assistance is by means of a new, tandem vacuum booster.

This booster combines a 7-inch and an 8-inch chamber into a more compact unit which is 50 rom (1.96 in.) smaller in diameter than a conventional single 10.5 inch booster.

- Anti-Lock Braking -

The GS version of the Integra is equipped with a computer controlled Anti-Lock Braking (ALB) system developed by Honda R & D Co., Ltd. It uses sensors at each wheel to detect impending lockup, which activates the system. In operation, ALB modulates hydraulic pressure, cycling the brakes as often as ten times a second. This allows the wheels to continue rotating with no loss of braking power, yet traction is maintained so that the driver retains stability and steering control.

This system is markedly different from others in that it contains two independent hydraulic circuits. There's a primary braking system which operates the brakes under normal conditions and the ALB system, which has its own hydraulic reservoir, pump, modulator unit, solenoids, control pistons and 16bit central processing unit. The system is similar to the one used in the Legend, but it is calibrated to the Integra's size and weight. If the ALB system fails, normal braking is still provided by the primary system.

- Wheels and Tires -

Integra RS and LS models are equipped with 5.5 JJ x 14 steel wheels with full wheel covers. The RS is fitted with 195/60 R14 85H tires, while Michelin MXV 195/60 R14 85H tires are used on the Integra LS. Integra GS 4-door models use 5.5 JJ x 14 alloy wheels with Michelin MXV 195/60R14 85H tires. The GS 3-dooi is equipped with alloy wheels' and uses Michelin XGT-V 195/60 R14 85V tires.

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