2003 Acura 3.2 TL -- Chassis
2/8/2002 1:28:33 AM
The TL was built with the ambitious goal of providing world-class refinement and exceptional handling performance. It is built on the Global Midsize Platform, a front-drive platform that combines the packaging efficiency and handling stability of a transversely mounted front-drive powertrain with Acura's latest chassis and suspension advances.
The chassis architecture of the TL has been carefully designed to provide the crisp handling dynamics demanded by driving enthusiasts and the world-class ride refinement expected by drivers of mid-luxury sedans. The TL employs front and rear suspension subframes and carries its engine on electronically-controlled hydraulic mounts. The 4-wheel independent suspension system benefits from geometric refinements that reduce understeer at the limit of adhesion and improve the TL's responsiveness. Standard 16-inch wheels on the TL and 17-inch wheels on the Type-S provide exceptional cornering grip.
The Type-S model's suspension has been tuned to provide even more exceptional handling, incorporating a larger-diameter rear stabilizer bar, stiffer front and rear springs, more compression and rebound damping, and longer front bump stops.
Chassis at a Glance
Ride and Handling
- Refined double-wishbone front suspension
- Multi-link, double-wishbone rear suspension
- 16-inch wheel and tire diameter for the 3.2 TL; 17-inch wheel and tire diameter for the TL Type-S
- Isolated front and rear subframes
- Three electronically-controlled hydraulic engine mounts
- Large front and rear discs along with drum-in-disc rear design allow separation of service and parking-brake systems-improving effectiveness in high-deceleration stops
- Anti-lock Braking System (ABS)
- Vehicle-speed sensing rack-and-pinion power steering on 3.2 TL
- For a more sporty feel, variable torque sensing rack-and-pinion steering is featured on the TL Type-S
- Standard Traction Control System (TCS) on 3.2 TL
- Standard Vehicle Stability Assist (VSA) system on Type-S (includes TCS)
- Standard Anti-lock Braking System (ABS)
The 3.2 TL utilizes a race-proven, double-wishbone suspension layout for exacting wheel-motion control. The front suspension has been carefully designed to exploit the stiffness of the front subframe, while the TL's low 57-mm roll center further contributes to the car's precise and linear handling.
To suit its more athletic demeanor, the Type-S front suspension is tuned for even greater handling performance. Revisions to the suspension include stiffer springs, a 10 percent increase in the damping rates, and a 20-mm longer bumpstop. These enhancements help the car maintain an optimum stance during cornering for superb handling and responsiveness.
At the rear, the TL's multi-link suspension layout has been designed for rewarding handling and a fluid ride without sacrificing cabin or trunk room.
Compact, high-tension steel suspension links reduce unsprung weight for enhanced damping control. The suspension geometry is designed to carry the rear wheels through a path that is angled rearward to improve bump compliance. This sophisticated geometry also provides a much straighter toe curve, meaning that during suspension motion there is a controlled amount of "rear steer." Pillow joints help control side-force steer while reducing component friction - improving ride comfort.
In the high-performance Type-S, the rear suspension - like the front - is tuned with stiffer springs, higher compression and rebound damping and a larger-diameter rear stabilizer bar for reduced body roll during cornering.
FRONT AND REAR SUBFRAMES
Stout front and rear subframes improve the TL's chassis rigidity and help curb NVH. In the front, a perimeter frame - consisting of a front member, side members and a rear bulkhead beam - significantly improves chassis stiffness while also enhancing front-impact crash protection.
The rear subframe also utilizes a large perimeter frame, consisting of robust cross-section members and smaller stringers that locate the rear suspension and house the fuel tank.
Both the front and rear subframes are mounted to the body with rubber isolators that help dampen vibration by as much as 5 db in the low- and mid-frequency ranges.
HYDRAULIC ENGINE MOUNTS
To enhance the world-class refinement of the TL even further, the V-6 engine is mounted to the subframe with two electronically controlled, hydraulic engine mounts and a side stopper mount. The hydraulic mounts help to isolate the cabin from engine vibration. To do so, each mount controls fluid transfer between two internal hydraulic chambers, thereby altering the mount's damping frequency and helping to counter any engine vibration.
To deliver both the smooth refinement of a premium luxury automobile and the rewarding response of an athletic sports sedan - the 3.2 TL and the TL Type-S are equipped with unique power-steering systems.
The 3.2 TL features a speed-sensitive, variable power assist system designed to complement the model's handling characteristics.
By varying the amount of power assist according to vehicle speed, the system provides light steering effort during low-speed parking maneuvers and, as vehicle speed increases, progressively heavier steering effort for a positive and secure feel.
The TL Type-S is equipped with an exclusive sport-tuned, power steering system (similar to the CL Type-S). The Type-S uses a torque-sensing rotary valve steering gear that varies the amount of assist according to steering input and the resultant torque generated between the pavement and tire. The system also varies assist based on engine speed, helping make steering light in parking maneuvers and heavier as speed increases for enhanced road feel.
The steering column is insulated from intrusive road harshness by a rubber coupling.
For superb braking power and excellent resistance to fade, the TL is equipped with 11.8-inch (300 mm) ventilated front brake rotors and 11.1-inch (282 mm) rotors at the rear. Rigid front calipers help provide crisp, responsive pedal feel, while system-wide tuning of the brake components helps ensure linear brake-pedal action and predictable effort.
The service and parking brakes on the rear wheels are separated for further improvements in brake performance. A drum-in-disc brake design uses the disc portion of the rear unit for braking at speed, while the drum is used only as a parking brake. The parking brake operates with a push on/push off floor pedal.
TRACTION CONTROL SYSTEM (TCS)
To enhance stability and control while increasing all-weather usability, the TL features a standard Traction Control System (TCS). Under acceleration, the TCS can detect wheel slip and, if necessary, coordinate modulated braking to help the front tires regain traction. Operating at vehicle speeds below 18 miles per hour, the system can apply one or both front brakes as necessary to control wheel spin.
Because the system provides independent drive-wheel control, it also greatly enhances performance when accelerating on surfaces with split-traction coefficients. When starting out on split-traction surfaces (i.e., one side of the car is on dry pavement while the other side is on wet pavement), TCS can apply braking action to whichever front wheel is slipping - allowing the tire with the better grip to propel the vehicle.
ANTI-LOCK BRAKING SYSTEM (ABS)
The ABS system in the 3.2 TL is a three-channel design that modulates braking power to the front wheels independently and to the rear wheels in tandem - enhancing driver control during maximum-effort stops on all road surfaces.
The TL Type-S is fitted with a four-channel ABS system that works in conjunction with the Vehicle Stability Assist (VSA) system. When braking in a straight line, the Type-S ABS system functions in the same three-channel mode as the 3.2 TL's. When the Type-S system senses high cornering forces, however, it automatically switches to a four-channel mode - allowing the ABS system to exploit the weight transfer to the outside of the turn and apply higher brake pressure to the outer rear wheel for enhanced braking performance.
VEHICLE STABILITY ASSIST (VSA) - (TL TYPE-S)
For enhanced control during acceleration, cornering, and sudden collision-avoidance maneuvers, the 3.2 TL Type-S is equipped with a standard Vehicle Stability Assist (VSA) system. Similar to the system first unveiled on the 2000 Acura 3.5 RL flagship sedan, the Type-S's VSA system enhances vehicle stability by applying brake force to either front wheel as necessary while managing the throttle and ignition systems.
Analyzing data that is constantly received from eight vehicle sensors, the VSA system compares the driver's control inputs with the vehicle's actual response. If the actual response is outside a predicted response range - as can happen when cornering forces exceed the tires' performance capabilities - VSA automatically intervenes with an appropriate corrective action. In the case of oversteer, VSA applies braking to the outside front wheel to counter the unintended yawing effect. If understeer is detected, VSA applies braking to the inside front wheel and reduces engine power to help bring the car back onto the driver's intended course.
The VSA system in the Type-S has been carefully calibrated to add handling stability and predictability without intruding on the process of spirited driving. Whenever the system is actively enhancing the vehicle's stability, an indicator light flashes on the instrument panel. In addition, VSA's stability enhancement and traction control can be disabled with a cockpit switch while still leaving the Anti-lock Braking system fully functional.
WHEELS AND TIRES
The 3.2 TL wears 6.5-inch wide by 16-inch diameter aluminum-alloy wheels and 205/60R16 Michelin MXV4 all-season tires.
The sportier Type-S receives larger diameter 17-inch by 6.5-inch wide aluminum alloy wheels shod with 215/50R17 V-rated, all-season, high-performance Michelin MXM4 tires for outstanding cornering capability.