1999 Acura CL Structure


Because luxury-car feel and safety were priorities of the CL project, the engineers concentrated on optimizing the rigidity of the CL unit body structure to provide excellent crash protection, excellent isolation from noise and vibrations and rewarding ride comfort. .

In developing the chassis, engineers used the latest Finite Element Analysis and Modeling to achieve the highest rigidity levels at the lightest possible weight. An important tool in achieving these high rigidity targets was "IDEAS" software from the Structural Dynamics Research Corporation in Cincinnati. This tool allows chassis designers to quickly analyze and evaluate changes in a structure and find the best solution.

Unit Body Structure

The carefully designed structure is designed to keep the center passenger section protected in the event of an impact. The center "safety cage" is specifically fortified with thickened reinforcements at such critical points as the floor tunnel, the side-sills, and the center pillars. The thickened rear damper stiffeners also extend downward over the wheelhouses. In addition to enhanced impact protection, these fortifications contribute to overall body rigidity and balance, imparting a quieter ride and a true luxury feel.

Rigid Strut Tower Bar

By carefully matching a rigid front strut tower bar to the specific characteristics of each CL engine, engineers were able to enhance both ride feel and steering response. In the event of a severe frontal collision, the structure is designed to crush at the tower bar center mounting bracket, helping to protect the integrity of the passenger cabin.

Rear Wheel Arch Extensions And Full Rear Bulkhead

Greatly improving torsional rigidity are exclusive rear wheel arch extensions. At each rear wheelhouse, this part creates a box section by connecting the side-sill box section with the rear-damper-stiffener box section.

In addition, a large shear plate ties the left and right rear wheelhouses together with the floor and the parcel shelf. Combined with the rear wheel arch extensions, this full rear bulkhead integrates the entire rear structure of the CL into a single unit, helping eliminate weak points and enhancing structural rigidity.

Polypropylene Impact Boxes

To supplement the side-impact protection provided by the CL's steel door-impact beams, the sides of the CL are equipped with polypropylene boxes that crush progressively and evenly in a side impact, helping to dissipate and distribute impact forces before they intrude into the passenger cabin. To reduce the likelihood of hip injuries, there is one box inside the lower part of each door and one under each rear armrest. Additional side-impact protection is provided by polypropylene foam blocks in the upper part of each door andjust above each rear side armrest. To reduce the likelihood of head injuries to rear-seat passengers in a side impact, special crushable box sections are also built into each C-pillar.

Sound Insulation

While the structure effectively damps out annoying vibrations and helps ensure a tight, rigid body, blocking out road noise is accomplished by using sound deadening material in strategic areas throughout the body. A liberal amount of insulating material has been used in the engine compartment, the floorpan, the rear bulkhead, the rear wheelhouse, and the trunk to ensure a quieter passenger cabin. To reduce splashing and drumming noise, the CL is insulated with a rigid composite material in the rear quarter-panels and in the rear wheelhouses. Additional noise control is provided by a PVC undercoating under the floor and in the wheel wells and by a fabric insulator under the hood.

Paint Process

To ensure a lustrous, lasting finish, each CL undergoes an exacting, 19-step painting procedure. The process begins by thoroughly cleaning the body of grease and other debris that might mar the final finish or prevent paint from properly bonding to the metal. The body is then put through an electro-deposition coating process, washed and then dried.

At that point, the actual process of painting begins. Each successive coat of paint and the sealer coat is baked and washed.

To improve the durability of the CL's fine finish, engineers developed a special antichip primer that is applied to parts of the body at particular risk from small stones and other flying road debris (such as the front of the hood). Thanks to improved tensile and elongation properties, this primer is able to distribute the impact forces of a small stone with little or no paint delamination.

Anticorrosion Measures

To ensure excellent corrosion protection, every CL outer body panel except the roof is made of double-sided galvanized steel.

In addition, the underbody is sprayed with an antichip, anticorrosion PVC undercoating, and selected cavities are filled with an oil-impregnated wax material that inhibits moisture penetration and prevents rust. This, when combined with the excellent painting process, produces a corrosion-resistant body that carries a 5-year rust-through limited warranty.

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