Acura Automobiles: 2015 Acura TLX: Chassis

The 2015 Acura TLX utilizes a newly designed chassis that incorporates next-generation versions of two pinnacle Acura super-handling technologies – Precision All-Wheel Steer™ (P-AWS) and Super Handling All-Wheel Drive (SH-AWD™). Both technologies are engineered to deliver intuitive and precise dynamic capabilities in a vehicle that responds directly and accurately to the will of the driver. These next-generation technologies are anchored by the TLX’s rigid unit-body structure and its MacPherson strut front and multi-link rear suspension with Amplitude Reactive Dampers (ARD). Stable and responsive vehicle dynamic behavior is further aided by Acura’s Agile Handling Assist (AHA) technology and, in emergency maneuvers, by Vehicle Stability Assist (VSA).

These chassis features help define the TLX as the most advanced Acura ever produced from a dynamic standpoint, a vehicle that supports the needs of the driver in all conditions – quick and responsive in sporty driving environments; stable and sure-footed in emergency maneuvers; calm and quiet during long-distance cruising – all based on the will of the driver.

The TLX also allows a substantial degree of customization through its Integrated Dynamics System (IDS) with four modes – ECON, Normal, Sport and Sport+ settings – that take the TLX from soothing to scintillating all at the touch of a button.

TLX chassis features found in this section include:

  • Front cast-aluminum and steel subframe
  • MacPherson strut front suspension
  • Rear steel subframe
  • Multi-link rear suspension
  • Amplitude Reactive Dampers (ARD)
  • Agile Handling Assist (AHA)
  • Vehicle Stability Assist™ (VSA®)
  • Integrated Dynamic System (IDS)
  • Motion-Adaptive Electric Power Steering (MA-EPS)
  • Precision All-Wheel Steer™ (P-AWS)
  • Super Handling All-Wheel Drive™ (SH-AWD®)
  • 4-wheel disc brakes with ABS
  • Electronic Brake Distribution with Brake Assist
  • Premium Bosch 6-piston brake modulator
  • Electric Parking Brake and Hill Start Assist
  • Aluminum alloy wheels
  • All-season tires
  • Tire Pressure Monitoring System (TPMS)
  • Fill Assist
  • Tire repair kit
  • Capless fueling system
  • 17.2-gallon fuel capacity

Front Cast-Aluminum and Steel Subframe
In a first for Acura, the TLX employs a cast-aluminum and steel “hybrid” front subframe to reduce road surface vibration and shock inputs for a smoother, quieter ride. The new subframe supports the engine, transmission, front suspension and steering system. The front section of the subframe is steel, and the rear section is cast aluminum. The sections are joined with a newly developed friction-stir-welding process to form a single high-strength, lightweight unit that provides ideal ride and handling properties. Altogether, the front subframe, along with a lower arm hydro-bushing, reduces vertical and fore/aft forces felt at front seats by 61 percent and 46 percent, respectively, compared to the previous TL model.

MacPherson Strut Front Suspension
MacPherson strut front suspension with Amplitude Reactive Dampers provides precise and engaging handling performance, a responsive feel for the driver, and luxurious ride quality. Specially tuned hydro-compliance bushings improve resistance to shimmy and while also reducing brake judder, further improving the TLX’s refinement and driving character. All TLX models have a 26.0 mm diameter tubular (hollow) front stabilizer bar.

Rear Steel Subframe
Constructed of high-tensile steel, the rear subframe uses hydraulic mounts, along with increased fitting-point stiffness, to reduce road surface vibration and shock inputs for a smooth ride and low noise. The rear subframe reduces vertical and fore/aft forces felt at front seats by 31 percent and 33 percent, respectively compared to the previous TL model. In addition, on TLX models with Super-Handling All Wheel Drive (SH-AWD), the rear subframe features a 4-point differential mounting system. Its bushing rates are specially calibrated to reduce the transmission of driveline noise and vibration into the vehicle body, while also helping to maintain ride quality.

Multi-Link Rear Suspension
Multi-link rear suspension with Amplitude Reactive Dampers provides optimal handling agility, driver confidence and ride sophistication. Geometry, including rear toe control, is optimized for handling competence, stability and a sophisticated ride in a variety of urban, highway and open road scenarios. The system includes multi-link control arms, control-arm bushings that are optimized for the best blend of noise, vibration and harshness (NVH) isolation and handling precision, and Amplitude Reactive Dampers. Both the 4-cylinder and SH-AWD models have a 24.7 mm diameter rear stabilizer bar, while the front-wheel drive V-6 has a 25.4 mm diameter stabilizer bar.

Amplitude Reactive Dampers (ARD)
Acura’s Amplitude Reactive Dampers provide both superior ride comfort and sporty handling, helping the new TLX provide a truly engaging driving experience in all driving situations. Two separate damping mechanisms are utilized, with one tuned for maximum efficiency on smoother roads with small inputs and the other tuned to handle large inputs such as rough roads, potholes, and sudden steering and braking action. Front triple-path damper mounts further improve ride comfort without sacrificing handling. The result is a vehicle that remains composed and comfortable in a wide range of conditions.

The core technology contained within the Amplitude Reactive Dampers is their two separate damping pistons, including a main piston and a second piston. To improve overall ride comfort, when smaller inputs occur during normal driving conditions, only the main piston works to provide the ideal damping characteristics. To improve the TLX’s ride and handling during more severe conditions, the second piston operates to provide additional damping force.

Amplitude Reactive Dampers operate on a purely mechanical basis that does not require electronic controls.

Vehicle Stability Assist™ (VSA®)
The TLX’s Vehicle Stability Assist™ (VSA®) works in conjunction with the Drive-by-Wire throttle system and ABS to enhance vehicle stability when cornering: If vehicle understeer or oversteer is detected, the system selectively reduces power and/or applies braking force to individual wheels to help correct the condition and stabilize the vehicle.

VSA also supports the functioning of available driver-assistive technologies such as Adaptive Cruise Control (ACC) with Low-Speed Follow (LSF), Collision Mitigation Braking System™ (CMBS) and Road Departure Mitigation (RDM). The advantages of the latest VSA system on the new TLX include quicker response with smoother activation and more accurate control, improved brake-pedal feel and lower operating noise, vibration and harshness (NVH).

In addition, traction control monitors front-wheel slippage, such as when starting on slick surfaces or patches of ice. If slippage is detected, traction control activates one or more brake calipers and reduces engine torque to slow the spinning wheel(s) so traction can be regained.

Integrated Dynamic System (IDS)
ECON, Normal, Sport and Sport+ modes allow the driver to customize their driving experience. The modes are driver-selectable via a console-mounted button and are displayed on the Multi-Information Display located between the tachometer and speedometer. ECON, Normal and Sport are selectable as default, or last used modes, while Sport + defaults to Sport at ignition off, and must be reselected after a restart. ECON mode favors high fuel efficiency, while Normal mode is for everyday driving. Sport mode enhances throttle, EPS and P-AWS response or SH-AWD rear-wheel torque-vectoring control to sharpen vehicle dynamics, while Sport+ mode enhances transmission shift mapping, maximizing performance.

Motion-Adaptive Electric Power Steering (MA-EPS)
The TLX’s next-generation Motion-Adaptive Electric Power Steering offers precise direct feel, high energy-efficiency, tunable response and improved active safety. MA-EPS responds instantly to steering input and automatically changes the amount of power assist appropriate to the vehicle’s speed. Its idealized steering effort and linearity, excellent on-center feel, minimal torque steer and maximum parking ease provides a satisfying driving experience under all conditions.

Additional features and benefits include:

  • Quick steering ratio helps provide a sharp, sporty dynamic response.
  • High-stiffness bushings improve steering precision and feel.
  • Next-generation control logic provides smoother feel on rough roads.

Motion-Adaptive Function
The Motion-Adaptive EPS system consists of a rack-and-pinion steering gear with an electric motor installed concentrically around the steering rack. To control the level of assist the Powertrain Control Module receives signals from a speed sensor and, coupled with a steering sensor for torque and rotation, then calculates the optimal amount of assist and sends a signal to the electric motor.

When compared to the operation of a conventional hydraulic pump power steering system, the simpler MA-EPS increases efficiency because it does not draw a continuous amount of power directly from the engine. Other advantages of electric power-assisted steering include simplicity, lower power consumption (which helps improve fuel efficiency), and compactness.

Vehicle Stability Assist (VSA®) Integration
MA-EPS and Vehicle Stability Assist (VSA®) work together as one sophisticated system to significantly enhance active safety. The stability technology initiates steering inputs that prompt the driver to steer in the correct direction when the limits of traction are approached.

Using vehicle speed and steering angle data, MA-EPS works with VSA® to detect instability in low traction conditions (both during cornering and under braking) and automatically initiates steering inputs aimed at prompting the driver to steer in the correct direction. This advanced technology supports the driver’s action in operating the vehicle more safely and comfortably.

Below are three examples of how MA-EPS works as part of VSA®.

  • Mitigates Understeer – Helps correct the steering inputs to mitigate understeer and help the driver trace the intended curve of the road.
  • Mitigates Oversteer – Helps correct the steering inputs to mitigate oversteer and help the driver trace the intended curve of the road.
  • Stabilizes Braking – Helps correct the driver’s steering input to reduce vehicle instability when the driver is braking hard on road surfaces with varying friction coefficients (such as pavement that is only partially covered with dirt or snow).

Integrated Dynamics System (IDS) Integration
MA-EPS also integrates with the TLX’s standard Integrated Dynamics System (IDS). At the driver’s discretion, the steering response can be switched between two distinct steering settings (Normal: when in Normal or ECON, and Sport: when in Sport or Sport+). (See below for more information.)

Precision All-Wheel Steer™ (P-AWS)
The latest version of Acura’s Precision All-Wheel Steer™ (P-AWS) helps the TLX driver smoothly and easily trace the desired line with smaller steering-wheel inputs. The result is best-in-class dynamic performance at all speeds, providing the TLX driver with the most engaging driving experience possible. Precision All-Wheel Steer (P-AWS) is standard on all two-wheel-drive TLX models.

P-AWS provides independent electronic control of rear-wheel toe angles. Benefits of the system include:

  • Minimized turning radius with neater execution of sharp low-speed turns
  • Improved response for quick steering maneuvers such as lane changes
  • Enhanced agility and nimbleness in tight, urban conditions
  • More confidence and control on curved highway on- and off-ramps
  • Greater agility on winding roads
  • Quicker and more effective emergency steering response
  • Increased straight-line highway stability
  • Confident braking stability
  • Improved high speed response and stability in winter driving and when Vehicle Stability Assist (VSA) is activated

P-AWS Operation
Key components of P-AWS include independent electrically assisted left/right toe-control actuators, special control arms and suspension uprights, and an electronic control unit that is linked via a dedicated Control Area Network (CAN) to the Electric Power Steering (EPS), Vehicle Stability Assist (VSA), braking and engine control systems.

In operation, P-AWS continuously monitors and calculates the correct amount of rear-toe angle input necessary for the conditions, analyzing steering input, engine and road speed, transmission, throttle position, brake pressure, yaw rate, lateral acceleration and other factors. The maximum amount of rear-wheel toe angle adjustment is 1.8 degrees in either direction (positive or negative) for a total range of 3.6 degrees.

P-AWS system operation automatically and continually matches driving situations such as turning at an intersection, driving on windy roads, when merging or exiting a highway, higher speed maneuvers or in snowy conditions. The P-AWS system provides confidence-building cornering capability through improved responsiveness and vehicle control. Examples include:

  • Secure Highway Cruising – When the driver initiates a lane-change maneuver requiring that the TLX neatly move into the next lane, the P-AWS system adjusts the rear wheel toe angles in phase (the same direction) with the front wheels enabling quick, clean and stable maneuvering.
  • City Agility and Easy Parking – For sharp low-speed turns, such as on city streets or in parking lots, the P-AWS system adjusts the rear wheel toe angles out of phase (the opposite direction) with the front wheels. This results in a tighter turning radius and reduces driver effort.
  • Fun to Drive on Winding Roads – When tracing the lines of a twisty road — and helping the TLX track confidently in snowy conditions — the P-AWS system counteracts understeer by helping introduce yaw — the necessary rotational effect — through the corner.

P-AWS Modes
P-AWS can provide rear-wheel toe-in, in-phase steering or out-of-phase steering, depending on the dynamic requirements as dictated by the system ECU specific key rear-wheel toe angle adjustments include:

Agile Handling Assist (AHA)
Agile Handling Assist (AHA) extends the P-AWS function by using the brakes in cornering to create yaw, or turning motion, helping the driver smoothly and easily trace the desired line with smaller steering-wheel inputs. AHA stabilizes the car earlier than conventional vehicle stability assist systems, resulting in more agile and engaging dynamic performance in everyday driving conditions.

Super Handling All-Wheel Drive (SH-AWD)
The TLX SH-AWD features a new hydraulically-controlled iteration of Acura’s acclaimed Super Handling All-Wheel Drive™ (SH-AWD®), which progressively distributes optimum torque not only between the front and rear axles, but also between the left and right rear wheels. Like its P-AWS counterpart, the TLX SH-AWD system is complemented by the brake torque effect of Agile Handling Assist.

The benefits of the SH-AWD system are superior all-weather handling and neutral, accurate steering under power. By rotating the outside rear wheel faster than the front axle while cornering, SH-AWD uses torque vectoring to create a yaw moment to help turn the vehicle through the corner — reducing understeer and improving controllability. With cornering forces more evenly distributed between front and rear tires, overall cornering power is increased — on wet or dry roads.

This next-generation SH-AWD system is 25 percent lighter and utilizes new hydraulic control to overdrive the rear wheels by 2.7 percent (compared to 1.7 percent for the previous system), enabling greater turning forces at reduced speeds and in tighter corners (see Powertrain for additional detail).

4-Wheel Disc Brakes with ABS and Brake Assist
The TLX is equipped with 4-wheel disc brakes with a 4-channel anti-lock braking system (ABS). The pedal feel is smooth and easy to modulate in light braking, and linear and pleasantly low-effort during medium and hard braking. The result is short, confident stops — with excellent pedal feel — under all conditions.

The front discs measure 12.6 inches in diameter, while the rear discs measure 12.2 inches in diameter. Weighing a total of 2.5 pounds less than the previous TL brakes, the lighter-weight TLX brakes help improve ride quality, handling capability and fuel efficiency. The brake pads are a high-friction type to optimize response and peak stopping performance even under strenuous conditions. The brake calipers are designed to reduce brake drag when not in use, reducing rolling resistance and improving fuel efficiency in the process.

The front brakes feature supplemental external vents that provide a second airflow path around the brake rotors, reducing thermal deformation by 51-percent. The byproduct of this better cooling is a 30 percent reduction in brake judder — felt by the driver as steering-wheel and brake-pedal vibration — during aggressive driving.

ABS independently modulates braking power at each wheel to help the driver retain steering control during heavy braking, while Brake Assist recognizes emergency braking situations and almost instantly applies full braking force when appropriate.

6-Piston Brake Modulator
The TLX employs a premium Bosch 6-piston brake modulator that provides the ultra-quick braking response required for Vehicle Stability Assist (VSA), Active Handling Assist (AHA), Low Speed Follow (LSF) operation, Road Departure Mitigation (RDM), and Collision Mitigation Braking System (CMBS). The brake modulator’s function is to build braking pressure almost instantaneously, and utilizing six pistons — instead of the two pistons in the previous TL brake modulator — it delivers significantly quicker response than before.

The new brake modulator also includes two additional pressure sensors, which ensure the smoothest possible pump operation. This reduces the potential vibration that might otherwise be felt through the TLX’s unit-body and brake pedal, improving overall braking-system refinement to an unprecedented level. In addition, a special Active Noise Shaping (ANS) chip incorporated into the motor controller circuitry measurably reduces noise during brake modulator operation. The operating algorithms of the system are proprietary and developed by Acura engineers.

Electric Parking Brake and Automatic Brake Hold
The combination of Electric Parking Brake (EPB) and Automatic Brake Hold meaningfully reduce the effort of driving the vehicle, thereby raising overall enjoyment and comfort for the driver.

Electric Parking Brake
The Electric Parking Brake (EPB) on the TLX makes using the parking brake easier and more comfortable. The parking brake now requires only a pull on a button on the center console. To release the parking brake, the driver simply presses on the accelerator pedal (while the seatbelt is buckled) or pushes on the parking brake switch. In addition to being simpler, more convenient and more comfortable to use than a traditional parking brake, the new Electric Parking Brake makes hill starts easier when the TLX is parked on a grade.

The one touch operation also promotes the use of the parking brake. As with a traditional manually activated parking brake, EPB functions on the rear wheels only. As an additional benefit, EPB weighs 9.7 pounds less than a traditional mechanical parking brake, helping to improve the TLX’s performance and fuel economy.

Automatic Brake Hold
The EPB also features Automatic Brake Hold, which retains brake pressure when the vehicle is stopped, simplifying driving in heavy traffic or hills. This frees the driver from continually pressing the brake pedal to maintain the vehicle in a stopped position, a significant improvement in driving enjoyment in difficult conditions.

Operating the system requires two simple actions from the driver:

  • Activating/deactivating the system via a switch on the center console
  • Pressing on the brake pedal when the vehicle comes to a stop

Once these steps are taken, Automatic Brake Hold will indicate engagement and then maintain brake pressure when the vehicle has come to a stop, even if the driver releases the brake pedal. The TLX then remains stopped — even on a hill — until the driver presses the accelerator pedal. At this point Automatic Brake Hold releases the brakes and the vehicle resumes normal braking function.

Wheels and Tires
All TLX models have 10-spoke aluminum alloy wheels, with the 2.4-liter TLX models featuring 17×7.5J wheels with black accents, while all V-6 models feature 18×7.5J wheels with gray accents.

All TLX models feature high-performance all-season tires that help deliver an ideal balance of ride and handling, high fuel efficiency, and low noise, vibration and harshness (NVH). The 2.4-liter TLX models are equipped with 225/55R17 tires, and all V-6 TLX models are equipped with 225/50R18 tires.

The wheel bearings are engineered with special low-drag seals that contribute to a 4.4-percent decrease in rolling resistance compared to a traditional wheel bearing seals.

Tire Pressure Monitoring System (TPMS)
A standard Tire Pressure Monitoring System (TPMS) helps the driver maintain proper air pressure to improve driving safety and fuel efficiency, as well as reduce wear and tear on the vehicle’s tires. Located in the Multi Information Display (MID), the TPMS graphic indicates the pressure in all four tires on a real-time basis. A TPMS icon illuminates to alert the driver whenever any of the tires has a significantly low-pressure reading that requires the driver’s attention.

Fill Assist
Debuting for Acura on the 2015 TLX is a technology called Fill Assist, which helps the driver inflate tire pressures to the correct level without using a pressure gauge. Instead, during inflation, Fill Assist sounds an audible alert when the tire reaches the required pressure.

Tire Repair Kit
The TLX features an easy-to-use tire repair kit in lieu of a spare tire. This reduces weight and increases trunk volume, and simplifies temporary repairs in the event of a flat tire. Acura Roadside Assistance supports tire repairs. In addition, a temporary spare tire is available as a Genuine Acura Accessory.

Capless Fueling System
The TLX’s capless fueling eliminates the fuel cap, meaning that fueling the vehicle simply requires opening the fuel lid, refueling, and then closing the lid. This smart and easy-to-use design eliminates the need to touch a dirty fuel cap, reduces the possibility of damaging the vehicle’s paint with the fuel cap or tether, or forgetting the fuel cap at the gas station. It also eliminates the possibility of activating an emissions warning by failing to properly re-install the fuel cap. And finally, the capless fueling system allows the use of a smaller fuel-cap door, which cleans up the lines of the vehicle.

The system consists of two integrated components, including an outer shutter mechanism that prevents the intrusion of dirt and dust, and a self-sealing fueling flap that is closed by a torsion spring. Both operate automatically.

At a gas station, the driver simply opens the fuel lid and then inserts the fuel nozzle. Inserting the nozzle automatically opens the outer shutter and fueling flap. When fueling is complete, removing the fuel nozzle automatically closes both the fueling flap and outer shutter.

17.2-Gallon Fuel Capacity
The TLX’s plastic fuel tank capacity of 17.2 gallons gives the TLX ample cruising range. The fuel tank is made of high-impact plastic for light weight and durability. The fuel tank is located in a protected area in front of the rear suspension.