2009 Acura TL - Chassis

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OVERVIEW

The 2009 TL is engineered to live up to the highest standards for a performance luxury sedan. With a wider track, larger tires (including newly available 18-inch and 19-inch sizes), and the availability of Super Handling All-Wheel Drive™ and the largest engine ever in an Acura sedan, the TL SH-AWD® is fully equipped to perform its mission.

Both the TL and the TL SH-AWD® are rewarding and entertaining to drive, whether around town or on a long, winding road to adventure. The same goes for seasonal driving. When equipped with SH-AWD® the TL is as confidence inspiring on wet or snowy roads as it is on dry pavement, and standard Vehicle Stability Assist (VSA®) makes the drive even more secure.

Unlike some competitors, who add all-wheel drive to their vehicles primarily to help conquer winter conditions, the available SH-AWD® was designed to enhance sporty handling and the vehicle's winter-driving capability. This means that the TL SH-AWD® is inspiring to drive year-round. Research showed that customers in this segment want overall driving character first-and that's the priority the TL focuses on, while simultaneously maintaining all-season capability.

The SH-AWD® Advantage

Along with the larger engine, the TL SH-AWD® also gets suspension, brake and steering upgrades that further sharpen its performance. The SH-AWD® system is ideally positioned to lead the performance luxury sedan category where the TL competes, as 35-percent of all vehicles in the class have all-wheel drive. Priced competitively with AWD packages on competing vehicles, the TL SH-AWD® is expected to be a strong competitor in the segment.

While the TL offers satisfyingly quick turn-on, flat cornering, a high level of grip and highly neutral characteristics when driven aggressively, with its larger and more powerful engine, and more sporting suspension tuning and tires, the SH-AWD® model takes performance a step further to deliver racetrack-quality handling-without losing the composure required of a daily driver.

UNIT-BODY STRUCTURE

A lightweight unit-body is the basis for a great-handling sport sedan, with low mass allowing quick acceleration, cornering and braking capability. Meanwhile, structural stiffness provides maximum suspension and steering precision, an ultra-quiet interior and lasting durability. The 2009 TL meets all these objectives with sophisticated unit-body engineering that provides maximum stiffness as well as low weight through the use of the highest volume of high-strength steel in Acura history, as well as the use of key aluminum components.

As a result of the front-suspension strut bar and a pair of additional lateral stiffeners at the front of the vehicle, lateral body rigidity is up 15-percent compared to the previous generation TL. In fact the new TL's unit-body is so rigid that six mass dampers formerly used to quell vibration have been deleted, for a weight savings of nearly 14 lbs.

Lightweight Materials

The use of aluminum for the TL hood, front and rear bumper beams, and instrument-panel beam helps reduce overall weight for improved acceleration, cornering, braking and fuel economy. A total of 51.7 lbs. is saved by the use of aluminum body components.

FRONT SUSPENSION

The 2009 Acura TL front suspension is double-wishbone system with spring, damper and stabilizer-bar rates tuned for performance handling while retaining a flat, comfortable ride. Stamped-steel upper and cast-iron lower control arms hold a forged-steel steering knuckle, with the upper arms attaching to the unit-body via special low-vibration pivot bushings and the lower control arms attaching to an aluminum box-section subframe via specially tuned conventional pivot bushings and hydraulic compliance bushings. The subframe is in turn connected to the unit-body via special vibration-reducing mounts. Nitrogen-charged blow-off dampers, coil springs, a stabilizer bar and a tubular steel shock tower brace complete the front suspension system.

The 2009 TL suspension is engineered to have 8-percent less front-end lift under acceleration (to reduce torque steer) and 37-percent less dive under braking than the previous TL. In addition, 22-percent greater roll stiffness keeps the body flatter during aggressive cornering. Lowering the TL's center of gravity and raising the front roll center by 1.7 inches also contributes to reduced body roll.

REAR SUSPENSION

In back, the TL's new multi-link rear suspension is similar to the system found in the 2009 Acura TSX. Like the front suspension, it features stamped steel upper A-arms with increased roll center height, while two steel tubular links and a single toe link provide the lower control. The lower links are mounted to a floating sub-frame that reduces the intrusion of noise, vibration and harshness (NVH) into the TL's cabin. A forged aluminum knuckle, nitrogen-charged blow-off dampers, coil springs and a 50-percent stiffer stabilizer bar complete the rear suspension.

The new rear-suspension geometry controls camber gain 40-percent better than the previous TL while the body is rolling in a corner, keeping a larger portion of the tire footprint on the ground for higher grip. Along with the new TL's lower center of gravity, a 1.5-inch higher rear roll center contributes to reduced overall body roll.

SH-AWD® SUSPENSION TUNING

The TL SH-AWD® has unique suspension tuning including special coil spring, damping and stabilizer-bar rates, and even special subframe mounting dampers-all tuned for flatter cornering with reduced pitching motions under acceleration and braking. The system is also tuned specifically for the all-wheel drive vehicle dynamics, as well as for the unique P245/45R18 tires on the TL SH-AWD®. As a result the TL SH-AWD® feels even more nimble than the front-wheel-drive TL in aggressive cornering situations.

"BLOW-OFF" DAMPER BYPASS VALVE

The 2009 TL has new dual-stage hydraulic "blow-off" suspension dampers with specially integrated spring bypass valves. The purpose of this feature is to provide maximum damping for large inputs and reduce the damping for smaller inputs. This in turn gives the TL sharp handling performance while filtering out the unwanted road imperfections.

HYDRO-COMPLIANT BUSHINGS

Another first for the 2009 TL is the use of hydro-compliant bushings on the lower front suspension wishbone. Rather than using a standard rubber bushing, the bushings are fluid filled, thereby significantly increasing the damping performance. This increased damping is particularly effective at improving ride quality and reducing brake judder vibration. Fluid-filled mounts are also used to isolate the TL transmission and engine.

HYDROFORMED STEEL REAR SUBFRAME

Road noise, vibration and harshness (NVH) is dramatically reduced through the use of floating rear subframe rails that carry the lower rear suspension links (and differential on the SH-AWD® model). The subframe is isolated from the body by specially tuned bushings, and uses hydroformed tubular steel side members for rigidity and a direct reduction of NVH in the passenger cabin. The hydroformed rails are created using hydraulic pressure that shapes steel tubing in a special mold. The result is light, strong and precisely shaped steel components that generate 17-percent reduction in rear chassis vibration.

NEW ENGINE MOUNT SYSTEM

The 2009 Acura TL engine features a new fluid-filled, hydro-compliant engine mount design that significantly reduces engine noise, vibration and harshness (NVH). The result is a 25-percent reduction in engine vibration, a substantial achievement that is noticeable and appreciated by the driver and passengers alike.

4-WHEEL DISC BRAKES WITH EBD AND BRAKE ASSIST

The 2009 TL has 4-wheel disc brakes with Electronic Brakeforce Distribution (EBD) and Brake Assist. While the previous TL used single-piston front brake calipers, the new TL employs dual-piston calipers in front with single-piston calipers handling braking duties in back. The calipers squeeze radially vented cast-iron front rotors and solid cast-iron rear rotors. The front rotors measure 12.6 inches in diameter (an increase of 0.8 inch over the previous TL) and the rear rotors measure 13.1 inches in diameter (an increase of 2.0 inches compared to the previous-generation TL). The new brakes generate a 21-percent increase in front brake pad contact area and 22-percent more brake-pad contact area in the rear.

SH-AWD® Brake Upgrades

In keeping with its mission as a premium performance sport sedan, the 2009 Acura TL SH-AWD® features special front fascia-mounted cooling ducts for the front brakes and proprietary vacuum booster specifications. The system upgrades allow even more confident and consistent braking in repeated high-use conditions such as during spirited mountain driving. Hill Start Assist (HSA) is also added to eliminate vehicle rollback when starting on a sloped surface.

ELECTRIC POWER STEERING (EPS)

Taking a cue from Acura's famed NSX supercar, the new 2009 TL uses an advanced form of Electric Power Steering (EPS). The system is designed to provide outstanding steering feel and optimally calibrated steering assist for performance driving. In addition, the EPS helps improve TL fuel mileage by 0.7 mpg in the city and 0.8 mpg on the highway by eliminating parasitic power losses associated with a traditional hydraulic power steering pump. Principal components of the EPS system are a torque-sensing steering box, the electronic boost motor located as an integral part of the steering rack, and a dedicated electronic control unit.

The biggest advantage for EPS is the ability to specifically tune the steering to suit the enthusiast driver. Computer algorithms recognize the vehicle speed and provide low steering effort for parking maneuvers, then begin to firm up as speed increases to increasingly provide a solid feel and linear response at higher speeds. The EPS tuning is unique for the SH-AWD®, featuring more pronounced steering effort build up at high speed.

The EPS system on the new TL requires 2.65 turns lock-to-lock vs. 2.8 turns on the previous Acura TL. Curb-to-curb turning is also improved, with the new TL achieving a 37.6 ft. turning radius versus 39.8 ft. on the previous TL-a significant accomplishment considering the new vehicle's longer wheelbase.

WHEELS AND TIRES

Large-diameter aluminum-alloy wheels and wide tires further complement the TL's dynamic and energetic body design. Their design and finish are formulated to go with the TL's emotional body design, and TL customers can choose between three different wheel sizes, designs and finishes. The TL and TL with Technology Package come with 17x8-inch 10-spoke wheels, the TL SH-AWD® and TL SH-AWD® with Technology Package have 18x8-inch 5-spoke wheels and available 19x8-inch 10-spoke wheels for the TL SH-AWD® with Technology Package.

2009 Acura TL tire choices include:

  • Bridgestone Turanza EL400 P245/50R17 98V M+S (TL)
  • Michelin Pilot HX MXM4 P245/50R17 98V M+S (TL with Technology Package)
  • Michelin Pilot HX MXM4 P245/45R18 96V M+S (TL SH-AWD® and TL SH-AWD® with Technology Package)
  • Michelin Pilot Sport S2 245/40ZR19 94Y (optional summer tire for TL SH-AWD®)

The spare tire is a space- and weight-saving T135/80D17 temporary unit located under the carpeted floor in the trunk.

Tire Pressure Monitoring System (TPMS)

Every 2009 Acura model includes a Tire Pressure Monitoring System. (Please see Safety section for more information.)

HILL START ASSIST

The TL SH-AWD® model has standard hill start assist that helps prevent the vehicle from rolling backwards when the driver switches from the brake to the accelerator while the vehicle is stopped on a hill. When the road incline exceeds an 8-degree threshold and the vehicle is fully stopped in any forward or reverse gear (with engine torque holding the vehicle), hill start assist automatically self activates. The hydraulic brake modulator is controlled by a longitudinal G-force sensor along with a wheel speed sensor and steering angle sensor. When hill start assist is active, the brakes automatically hold for two seconds as the driver's foot lifts off the brake. The brakes are automatically released when the driver presses the throttle to make the vehicle move and sufficient drive torque is applied.

ROAD NOISE

The 2009 TL is designed to be one of the quietest cars in its class. Both the front-drive and SH-AWD® versions offer significant reductions in NVH compared to the previous generation TL. But because many enthusiast drivers like to hear the engine and exhaust note when they're aggressively on the throttle, the TL SH-AWD® exhaust system is tuned to have a sportier note to satisfy performance drivers.

Apart from a specific exhaust note on the TL SH-AWD®, Acura engineers focused intently on eliminating undesirable road noise. A highly rigid unit-body, special suspension and subframe bushings, precisely tailored spring and damper rates, and even details such as PVC undercoating and foam filled A-, B- and C-pillars, dramatically reduce unwanted noise. Additional noise-attenuation features include heat-molded felt inner liners for the rear fenders.

TRACK TESTING

Acura conducted extensive validation testing of TL prototypes literally around the world. SH-AWD® tuning was conducted in New Zealand, testing on city streets was done in Southern California, corrosion performance evaluations were conducted in Nova Scotia, and snow and cold-weather testing was done in Minnesota as well as in Alaska. In addition, cooling and brake tests were performed in Death Valley, high-altitude testing was done in the Colorado Rockies, and performance tuning was conducted in Japan, at the famed Nürburgring circuit in Germany and at Virginia International Raceway, where the TL SH-AWD® proved highly competitive with its premium class competitors.

ACTIVE SAFETY

Standard active safety features on the 2009 TL include an Anti-lock Brake System (ABS), Vehicle Stability Assist™ (VSA®) Electronic Brake Distribution (EBD) and Brake Assist. VSA® is an electronic stability control system that continuously monitors lateral acceleration, steering wheel angle, and wheel speed and yaw rate-and then applies individual brakes and/or reduces engine power to help the driver retain directional control of the vehicle. (Please see Safety section for more information.)

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