2013 RDX - Chassis
Like its predecessor, the 2013 RDX rides on 4-wheel independent suspension that utilizes a MacPherson strut design in front and a multi-link design in back. However, a longer wheelbase, increased track width and a lower center of gravity help give the new RDX improved handling with a more subtle ride. Further optimized chassis mounting points with increased rigidity help generate more precise handling. New chassis technology abounds in the 2013 RDX in the form of items such as all-new Amplitude Reactive Dampers and a new motion adaptive electronic power steering system that replaces the previous hydraulic steering.
The development of new RDX involved using the good handling qualities of previous generation RDX and then to add even more character. "High contrast" was the core theme in the development- meaning the new RDX looks more sophisticated and comfortable on the outside, but still offers driving pleasure with none of the traditional SUV driving dynamics. Such goals for dynamic performance and ample utility were not easy to achieve, yet Acura designers answered this challenge by giving the RDX a low center of gravity. The result is an especially confident driving experience- whether in tight corners on a mountain road or the open road during a family trip.
Acura engineers created a vehicle that transcends the traditional SUV driving experience. As a result, the 2013 RDX simultaneously provides sport minded driving on twisty roads, smooth ride characteristics on the highway and compliant handling in the city.
The independent front suspension used with the 2013 RDX is a specially tuned MacPherson strut design with compact packaging. The suspension offers long wheel travel and the ruggedness necessary to meet harsh urban roads. The suspension geometry has been optimized with both a high caster angle and "trail" to provide sharp on-center steering response and stability.
Additional specifics of the front suspension that help achieve sports sedan-like handling include:
- High-friction upper strut mounts that provide good on-center steering feel, along with increased linearity while reducing steering shimmy
- Side-specific, symmetrically wound coil springs to improve steering quality
- All-new Amplitude Reactive Dampers
- Rebound springs
- Large-diameter lower arm compliance bushing to help reduce NVH
- Optimized kingpin layout to enhance steering feel and linearity
- A larger (22mm) diameter anti-rollbar to help control body roll for flatter cornering
- Wider front track width (+1.2 inch) than before
A multi-link design independent rear suspension system with aluminum knuckles fits compactly underneath the rear seating and storage areas of the RDX. The suspension uses large-diameter trailing arm bushings to reduce harshness and improve ride comfort. A special steel suspension subframe with large "floating" bushings reduces NVH, while overall stability improves thanks to stiffer mounting points due to a more rigid rear body structure.
Rear suspension features:
- Special anti-squat geometry to reduce body pitching while under acceleration
- All-new Amplitude Reactive Dampers
- Rebound springs
- 19mm diameter rear stabilizer bar helps deliver flatter cornering
- Wider rear track width (+0.8 inch) than before
AMPLITUDE REACTIVE DAMPERS
A new technology for Acura, Amplitude Reactive Dampers are used on the 2013 RDX to provide a superior level of ride comfort together with crisp, precise handling. The dampers operate in two distinct performance parameters, including a Ride Zone and a Handling Zone. Each zone has a unique set of compression and rebound damping forces tailored to provide the desired ride and handling attributes. In essence, the amplitude reactive dampers operate like two separate suspension systems combined in one. The new dampers are entirely mechanical in operation with no electronics required.
For short suspension stroke (between 1-5 mm travel), the dampers provide minimal damping effect to provide an extremely comfortable ride where little suspension travel is needed- such as on smooth road surfaces.
For longer suspension stroke (over 10 mm travel), a second damping circuit is engaged. Here damping effect is maximized for enhanced steering feel, improved body-roll control and more secure handling- such as during aggressive cornering or on severe road conditions.
With the Amplitude Reactive Dampers, by adding a second spring floating valve (the previous generation RDX only had one conventional valve) above a conventional main piston valve, the 2013 RDX is able to maintain the superior driving dynamics of the previous model, and further improve ride qualities to that of a sedan.
For example, while driving on rough surfaces, the application of short-stroke damper movement allows the main piston valve absorb the small vibrations for a comfortable ride. However during hard cornering both the main and second piston valves move that create a much larger damping force for better driving dynamics.
Input Separation Bushings
The 2013 RDX adds input separation damper mounts to the rear suspension (previous model only had them in front), which supports the amplitude reactive damper to help improve ride stability and driving dynamics. The input separation damper mount helps absorb and more evenly distribute damping forces that are normally passed on to the body. For example during cornering on rough surfaces, the damper mounts transfer damper force more efficiently to the body, helping to stabilize spring movement.
The 2013 RDX makes use of an all-new Motion-Adaptive Electric Power Steering (EPS) system- the first-ever use for Acura. Standard on all 2013 RDX models, this sophisticated new steering system links the vehicle stability assist (VSA) and Electric Power Steering to help detect handling instability experience on slippery roads as well as under braking. The system automatically initiates inputs that prompt the driver to steer in a direction to help mitigate the unstable driving condition.
Motion-Adaptive Electric Power Steering (EPS)
Standard on all 2013 RDX models, Motion-Adaptive EPS is a sophisticated new system that incorporates driving stability technology which initiates steering inputs that prompt the driver to steer in the correct direction during cornering and when experiencing slippery road conditions.
Using vehicle speed and steering angle data, Motion-Adaptive EPS works with Vehicle Stability Assist (VSA®) and Electric Power Steering 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 new advanced technology supports the driver's action in operating the vehicle more safely and comfortably.
Noted below are three examples of how Motion-Adaptive Electric Power Steering (EPS) functions in conjunction with 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 different friction coefficients (such as pavement that is only partially covered with dirt or snow).
With Electric Power Steering (EPS), a sophisticated electric power-assisted rack-and-pinion steering system takes the place of a conventional hydraulic power steering system. EPS responds instantly to steering input and automatically changes the amount of power assist appropriate to the vehicle's speed.
The Motion-Adaptive EPS system consists of a rack-and-pinion steering gear with an electric motor is located next to pinion axle. 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 more simple Motion-Adaptive 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 its simplicity, its lower power consumption (which helps improve fuel efficiency), and its compactness (and resulting lower overall weight).
The steering ratio on all RDX models is 15.0:1 (2012 RDX was 15.1:1), resulting in 2.7 turns lock-to-lock (2012 RDX was 2.8 turns) and a curb-to-curb turning diameter of 39.0 feet (2012 RDX was 39.2 feet).
WHEELS & TIRES
With all new exterior sheetmetal for 2013, the RDX also receives new large-diameter aluminum wheels and wide tires that further complement the RDX's exterior design. RDX features as standard bold new split 5-spoke 18x7.5-inch aluminum wheels with specially developed Michelin Primacy MXM4 P235/60R18 all-season tires designed with particular focus on reduced road noise and lower rolling resistance (improved fuel economy). Much time was spent tuning the tires so that noise and harshness was reduced- but without negatively affecting overall handling performance.
The spare tire is a space- and weight-saving T165/90R17 temporary unit that is located in the floor (under a cover) in the rear cargo area of the RDX.
4-WHEEL DISC BRAKES
While the 2012 RDX provided excellent stopping performance, for 2013 the RDX receives numerous braking improvements regarding performance as well as safety. The front brakes now feature more rigid single piston cast-iron calipers that clamp larger diameter (312 mm vs. 296 mm) rotors. For 2013, the front calipers have a special trim plate that improves looks and prominently displays the Acura name. The 12.3-inch diameter front rotors feature a Geomet coating for improved looks and added rust prevention. In addition, the front rotors are a new design that incorporate more internal cooling vanes (60 vanes versus 42) to improve braking performance.
The rear brakes feature 12.0-inch diameter solid rotors (with Geomet coating) that team with single piston cast-iron calipers. Both the front and rear brake rotors connect to hub bearings that apply new low-friction seals that reduce drag by approximately 20 percent.
For 2013, the stroke ratio of the brake pedal has been reduced by 7-percent which generates more aggressive braking results.
An Anti-lock Braking System (ABS) with Electronic Brake force Distribution (EBD) is standard on the RDX. ABS helps the driver retain vehicle control during hard braking and EBD automatically proportions brake power to the rear brakes according to the vehicle load and driving conditions, helping to improve stopping performance.
The RDX also has Brake Assist, which uses a microprocessor that recognizes the driver's intention to quickly apply the brakes in a panic stop situation. In this case, Brake Assist immediately supplements the braking force, enabling the best braking performance in the moment when it's most needed. Brake Assist only supplements the driver's intentions, and its function terminates immediately when the driver releases the brake pedal.
In addition to ABS and EBD, new electronic technologies include with Hill Start Assist.
Hill Start Assist
New for 2013 is hill start assist (HSA) that helps prevent the RDX 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 a 5-percent incline and the vehicle is fully stopped in any forward or Reverse gear (with engine torque holding the vehicle), HSA 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 momentarily hold as the driver's foot lifts off the brake. The brakes are automatically released when the driver presses the throttle, sufficient drive torque is applied, and the vehicle begins to move forward.
VEHICLE STABILITY ASSIST WITH TRACTION CONTROL
Vehicle Stability Assist™ (VSA®) is included as standard equipment on the 2013 RDX. By continually monitoring the vehicle's operating parameters (such as vehicle speed, throttle position, steering angle, individual wheel speeds, lateral G-force and yaw rate), VSA® detects if the vehicle is about to experience oversteer or understeer.
To help correct either of these situations, 4-channel VSA® automatically reduces the engine's power output as needed, and applies one or more brakes individually to help stabilize the chassis. The VSA® response is so quick that the instability may be corrected even before the driver knows that it is occurring. Traction Control is integrated into the VSA® to help the RDX accelerate smoothly on slippery surfaces. If required, Traction Control can be disabled.
TIRE PRESSURE MONITORING SYSTEM
Acura RDX has an onboard Tire Pressure Monitoring System (TPMS) that warns the driver if the air pressure decreases significantly in any tire. The system helps reduce the chance of damaging a tire or losing control of the vehicle due to low air pressure. This is important because a slow leak might not be easily detectable but could over time cause significant air loss resulting in loss of grip or potentially a blowout.
TPMS uses a sensor mounted in each wheel that continually monitors tire pressure and sends a coded signal to the TPMS electronic control unit (ECU). The process begins with a signal initiator located on the chassis just inboard of each tire. The initiator sends a unique signal for each TPMS sensor. Then the TPMS sensor sends tire pressure data to the TPMS ECU, which compares the values for each tire's pressure against an acceptable range of pressures.
The Multi-Information Display (MID) can simultaneously display the air pressure in all four tires, making it simple to locate a low-pressure tire.
FUEL TANK AND DRIVING RANGE
The RDX's 16-gallon fuel tank is located in a protected position under the body and forward of the rear wheels. The RDX has an EPA estimated* city/highway/combined fuel economy of 19/27/22 mpg (AWD) and 20/28/23 (2WD), which gives it an estimated highway range of approximately 430 miles (AWD) and 450 miles (2WD) miles on one tank of fuel. The use of Premium fuel is recommended (but not required) for the 3.5L V-6 engine in the 2013 RDX.
*Based on 2013 EPA mileage estimates. Use for comparison purposes only. Your actual mileage will vary depending on how you drive and maintain your vehicle.
1,500-POUND TOW RATING
For added utility, the RDX has a 1,500-pound tow rating when equipped with the available towing package. The tow rating makes the RDX capable of pulling items such as a small camping trailer, a motorcycle trailer or a personal watercraft.
Like all products from Honda of America Manufacturing's facility in Marysville, Ohio, the RDX follows strict guidelines for environmental care- both in the manufacturing process and in the actual vehicle components. The 2013 RDX is manufactured with U.S. and globally sourced parts. The following is a partial list of environmental processes used in creating the RDX that reduces its long-term environmental impact.
- More than 90-percent of RDX parts are made of recyclable materials
- The use of non-chromed tanned leather reduces hazardous waste generation during the tanning process
- Elimination of PVC in most interior parts and exterior improves recycling ability
- Wheel balance weights and electro-deposition paints do not contain any lead