2009 Acura TSX - Chassis
4/20/2008 1:01:00 PM
In keeping with its lean, athletic appearance, the 2009 TSX offers a flat ride that is free from excessive pitching motions, along with outstanding agility and steering precision. As a result, the chassis serves a broader mission than that of the previous-generation TSX. Several advancements are responsible for this, including a more rigid body design including a new cross-braced roof structure and a new safety cage-type rear bulkhead structure.
The 2009 TSX suspension's roll center (the geometric axis on which the body rolls or leans while cornering) has been raised compared to the previous generation TSX. This revised roll center reduces body lean during cornering, which better equalizes the workload for all four tires while also improving passenger comfort.
Double-wishbone front suspension components include stamped-steel upper A-arms, cast-iron steering knuckles, cast-iron lower A-arms, coil-over dampers and a larger/thicker (26.5 mm diameter hollow versus the previous 25.4 mm hollow design) front stabilizer bar. A steel subframe cradles the engine, transmission and lower suspension components, and mounts on rubber bushings tuned to reduce road and engine noise, vibration and harshness (NVH) without compromising handling agility or steering precision.
The multi-link rear suspension includes stamped-steel upper A-arms, cast aluminum knuckles, double lower tubular lateral links, tubular steel toe-control links, coil-over dampers and a larger (17 mm solid versus the previous 15 mm solid) stabilizer bar. This system provides outstanding agility and handling, together with a flatter ride and excellent control of noise, vibration and harshness (NVH).
The 2009 TSX features dual-mode dampers, a first for an Acura vehicle. While most conventional dampers are tuned to provide a compromise between ride comfort and sporty handling at different speeds, the TSX's new dual-mode dampers are engineered to provide ideal damping rates at both low and high speeds.
With a typical suspension unit, damping forces rise with the speed of damper compression, such as occurs when the vehicle encounters road irregularities at high speed. This can cause significant ride harshness and noise that reduces passenger comfort and enjoyment. However the new TSX's dual-mode dampers are tuned to provide the ideal damping rates for comfort and smoothness at low speeds of damper compression, while also limiting the maximum damping forces to reduce ride harshness at higher speeds of damper compression.
In this way the 2009 TSX provides a wider range of comfortable ride quality and exceptional road holding under a wide variety of driving speeds and conditions.
Deflector plate technology
Acura's dual-mode dampers automatically adjust compression damping characteristics to suit the vehicle speed, cornering forces and road surface. The dampers use an ingenious "deflector plate stack" that deflects when the compression forces reach a certain level, such as when encountering a large bump or dip in the pavement at high speeds. When these severe forces act on an ordinary damper, oil cannot move quickly enough through the damping orifices and the effective damping rate climbs, resulting in an excessive shock transmitted into the vehicle body.
With the 2009 TSX's dual-mode dampers, when severe conditions are encountered, the plate stack deflects, allowing oil to pass through at a higher rate and in essence "capping" the damping rate at a preset level. Allowing an increased flow rate in extreme situations noticeably reduces the shock transmitted into the body while enhancing handling stability and road holding.
Deflection of the plate stack is carefully calibrated and controlled by spring pressure force on the plate stack. The simplicity of the dual-mode damper system also means that no electronics or movable valves are required.
ELECTRIC POWER STEERING (EPS)
Another first for the TSX model is the use of Electric Power Steering (EPS). Rather than powering a hydraulic steering-assist pump via the engine's serpentine accessory belt, as used with the current TSX, in the 2009 model the steering assist is via a computer-actuated electric motor.
With typical hydraulic steering assist, the steering force required from the driver is reduced as speed increases. But with computer-controlled EPS, advanced algorithms built into the operating software allow fine-tuning the required steering forces so that minimal force is required at low speeds - such as when parking or maneuvering. Progressively higher steering effort is needed at higher speeds - such as when driving on the freeway.
The EPS system found in the 2009 Acura TSX is an evolution of an earlier EPS system found on the Acura NSX supercar. Its key features and advantages include:
- The TSX's new EPS system reduces the steering effort at low speeds, improving agility and ease of effort.
- Rigidity of the steering mount is 380-percent higher, which allows a much more precise and "connected" feeling during high-speed maneuvers such as lane changes or winding mountain roads.
- The steering assist is programmed via computer algorithms according to vehicle speed rather than engine speed, allowing designers the flexibility of tailoring the steering feel to match driving conditions, especially high-speed driving. The steering boost algorithms are minutely altered for every 1 km/h (0.6 mph) change in vehicle speed.
- EPS allows the utilization of a sportier, quicker steering ratio (14.8:1 vs. 16.0:1 as used on the previous TSX), which further improves driving agility.
- In its evolution from the original NSX system, the 2009 TSX's EPS system uses a significantly more powerful electric motor teamed with a more sophisticated microprocessor.
- By eliminating the conventional power steering pump, EPS uses less engine power, benefiting acceleration and fuel economy.
4-WHEEL DISC BRAKES WITH ABS
Like its predecessor, the 2009 Acura TSX features 4-wheel disc brakes. The front rotors measure 11.8 inches in diameter - the same as the previous generation - and are made of cast iron with radial vents for excellent heat dissipation and wear properties. At 11.1 inches diameter, the rear rotors are nearly an inch larger than on the previous-generation TSX, providing enhanced braking capability during repeated use. Floating-style single-piston cast-iron brake calipers are used front and rear.
A sophisticated 4-channel Anti-lock Braking System (ABS) is standard and works in concert with the vehicle's Traction Control System (TCS), Brake Assist, and Vehicle Stability Assist (VSA) systems for an outstanding array of electronic dynamic aids.
WHEELS AND TIRES
The 2009 TSX comes standard with 17x7.5-inch 5-spoke aluminum alloy wheels and Michelin Pilot HX MXM4 P225/50R17 all-season tires developed specifically for the vehicle. The wheels have a clear-coat aluminum finish designed to compliment the exterior color choices. Located under the trunk floor panel is a T135/80D16 temporary spare tire mounted on a 16x4-inch steel wheel.
Dynamic testing and final chassis tuning for the 2009 TSX was conducted both in Japan and in America. The TSX was specifically tuned for the best combination of agility and handling needed in an urban environment, and at higher speeds. The Los Angeles area, with its huge variety of surfaces, freeways and topography, proved invaluable in chassis tuning to achieve a balanced overall package. Also invaluable was a "mini-Nürburgring" test course built in Japan especially to replicate some of the most demanding elements of the famed German racetrack.
An exciting line of Genuine Acura Accessories was developed simultaneously with the TSX to provide personalization for the Acura Client. Like all Genuine Acura Accessories, the TSX accessories are covered by a 4-year/50,000-mile limited warranty.
- 18-inch diameter 10-spoke alloy wheels (chrome-look or ebony finish)
- Wheel locks
- Sport bumper kit
- Rear bumper appliqué
- Deck lid spoiler
- Wing spoiler
- Color-matched splash guards
- Body side protection molding
- Door edge guards
- Car cover
- Moon roof visor
- Door visor
- Back-up sensors
- Engine block heater