Quick handling response, nimble performance, high dynamic capabilities, outstanding ride comfort and a fun-to-drive character were the design goals for the 2005 Acura RL chassis. The RL features a highly rigid unit body that provides an excellent platform for the four-wheel independent suspension (independent front double-wishbone with independent multi-link rear). Aluminum suspension components front and rear cut unsprung weight to allow for more supple and responsive suspension action and more consistent traction and handling on rough roads. The optimized suspension geometry of the RL works with new electronically controlled power steering, larger wheels and tires and the Super-Handling All-Wheel-Drive system to give the RL exceptional handling balance in virtually every driving condition. Ride quality and road noise isolation were also the focus of substantial engineering effort, so even with its elevated sporting performance, the RL remains quiet and composed.

CHASSIS CONCEPT

The 2005 RL was designed to compete squarely with the best luxury sedans from Germany and Japan in dynamic performance interior luxury appointments, features and quality.

The new suspension works with the SH-AWD system to provide superb handling precision. The suspension's optimized geometry provides linear cornering feel, outstanding dry and wet weather cornering capabilities, a flat ride, and a high level of controllability at all times. It also results in an increased feeling of precision and security for the driver and passengers alike.

Front Double-Wishbone Suspension

The front suspension is a double-wishbone type with an enlarged subframe mount and compliance bushing as compared to the 2004 3.5 RL. In addition, the dampers now feature rebound springs that reduce chassis attitude changes to ensure a flat ride during acceleration and cornering.

Specific improvement goals for the RL suspension included better response over rough roads, improved steering feel, optimized geometry, and overall component toughness. The steering knuckle (or upright), upper arm, lower arm and subframe are all lightweight aluminum.

Rear Multi-Link Suspension

The rear suspension is a multi-link type with a new enlarged subframe mount and a longer upper arm design. As a result the roll center is optimized for better turning response, cornering stability and control in extreme conditions.

The optimized geometry results in linear toe and camber changes during suspension travel. Improved roll stiffness also makes the RL corner flatter than the previous model. It also has anti-lift characteristics to reduce the pitching motion of the body during braking.

Harshness and road noise are also significantly reduced, and ride comfort is also measurably improved, thanks to these changes and a new compliance bushing.

Lightweight aluminum is used for weight savings in the control arms and subframe. The components are also stiffer to withstand the higher side loads that SH-AWD, larger tires and a stiffer unit body create.

Aluminum Hybrid Subframes

The RL front and rear aluminum subframes are composed with members made by high temperature bulge forming and high vacuum die casting. Both manufacturing techniques result in significantly lighter units than would be possible with either aluminum hydroform or steel hydroform processes.

To bulge-form these components, an aluminum tube is heated and pressurized with air inside a specially shaped die. The ability to shape the component under both heat and pressure means that less material can be used, lowering the overall weight of the finished component.

The aluminum hybrid subframes on the RL save over 17 lb. as compared to those of the Acura TL, and save nearly 40 lb. compared to comparable steel hydroformed subframes like those of the Acura TSX. The exact weight savings are shown below.