Chevy Shakes Up IRL Chassis Development

    RICHMOND, Va., June 26, 2002 -- Like secret agent James Bond,
who preferred his martinis shaken instead of stirred, Chevrolet teams are
shaking things up in the Indy Racing League. The shaker they use can't be
found in any bartender's kit, however. They rely on an instrumented
seven-post rig that accurately simulates the stresses and strains of
oval-track racing in a laboratory environment. Information generated on a
seven-post rig can be invaluable on a challenging track like Richmond
International Raceway's tight .75-mile oval, the site of Saturday night's
250-lap SunTrust Indy Challenge.

    Like wind tunnels and dynamometers, the seven-post rig is another tool
in GM Racing's race car development kit. While a wind tunnel gauges
aerodynamic performance and a dyno measures engine output, the seven-post
rig puts the chassis and suspension to the test.

    "A seven-post rig allows a racing team to recreate the vehicle's
behavior on the track in a controlled environment," said Kevin Bayless, a
chassis and aerodynamics consultant for GM Racing who works closely with
Chevrolet IRL teams. "The device is called a 'seven-poster' because there
are typically seven hydraulic actuators that work on the car."

    Unlike a paint can shaker at the local hardware store, the
seven-post rig's hydraulic plungers and rams are precisely controlled by a
computer to reproduce the loads encountered on the track. Similar systems
are used to evaluate the ride and handling of GM production vehicles.

    "The race car sits on four wheel actuators that simulate a variety of
road inputs," Bayless explained. "Three additional actuators simulate
the aerodynamic downforce produced by the wings and ground effects, as well
as the suspension loads produced on a banked oval. These actuators also
provide a means to roll the vehicle to evaluate cornering performance.

    "The seven-post rig allows us to analyze the effects of various
suspension settings on the race car's wheels loads and ride height,"
Bayless continued. "It permits a team to work through a variety of spring,
damper and roll bar packages quickly to develop an optimum combination."

    Like any laboratory tool, the seven-post rig has limitations, however.

    "After we develop a package on the seven-post rig, it still must be
tested and proven on the track," Bayless noted. "Setups that look promising
on the seven-poster don't always work in the real world.

    "Chassis and suspension development on a seven-post rig is still in
its infancy, and we're continuously learning more about the process,"
he explained. "The interactions between the suspension, the chassis,
the aerodynamic loads and the track are extremely complex. Of course, the
driver must also feel confident and comfortable with the setup, and that's
something that can't be evaluated on a test rig. However, the seven-poster
does allow us to identify potential gains in performance that warrant
further testing."

    With the introduction of sophisticated tools like the seven-post
rig, there's a whole lotta shakin' goin' on in the world of Indy car
chassis development.