The 3.5RL has a stamped-sheet-steel unit-body structure, designed to have a very high level of overall rigidity in both bending and torsion. The highly rigid structure was developed using a Cray supercomputer running the NASTRAN finite element-analysis program originally developed by NASA for building space vehicles. Last year, the 3.5RL chassis was made even more rigid through the addition of a rear parcel shelf support gusset and a larger bulkhead bracket and improved rigidity of the rear crossbeam stabilizer. Torsional and bending rigidity were boosted 20 and 15 percent, respectively.
The improvements in rigidity made during the 3.5RL development process have reduced noise and vibration in the passenger cabin, enhanced handling precision and stability, created excellent safety performance and increased overall durability. A high proportion of galvanized panels are used in the 3.5RL structure and body panels for enhanced corrosion protection and overall longevity.
OVAL-SECTION FRONT TOWER BAR
Instead of a conventional tubular steel front brace between the firewall and the upper front-suspension locating points, the RL uses an oversized, oval-section tower bar brace, as well as a reinforcing plate that ties the firewall and front cowl section. This design increases rigidity as much as 12 times over a conventional round tube design, reducing cowl shake on rough roads and in spirited driving, while increasing steering precision.
FOAM-FILLED B- AND C-PILLARS
For reduced cabin-noise transmission, the B- and C-pillars are filled with a special heat-expanding rubberized foam material that expands to fill the hollow pillar during the baking cycles of the painting process.
HONEYCOMB FLOOR PANELS
Special lightweight honeycomb panels are used in the floor structure to increase rigidity and reduce noise and vibration. These panels are composed of a resin-impregnated fiber matrix bonded top and bottom to thin-gauge galvanized steel sheets.