Extremely low mass vehicles are often penalized by poor suspension design. Just the opposite approach is necessary in order to bring out the natural handling capabilities of a low mass vehicle. Whereas a high mass vehicle has greater inherent stability, a low mass vehicle has greater inherent agility and handling precision. These natural characteristics can be degraded by poor design, or they can be enhanced by good design. Use the following general guidelines with low mass vehicles.
Use the fully-laden weight for performance and handling calculations.
Keep unsprung weight to a minimum. Consider a simplified suspension design, and use lightweight alloys or plastic composites for springs and structural members.
Keep the center of gravity as low as possible. Correct cg location is especially important in low mass vehicles, and even more so in three wheel designs.
The center of gravity should be ahead of the wheelbase mid-point of a four wheel platform, and no farther than 35 percent of the wheelbase from the side-by-side wheels of a three wheeler.
The tread should be as wide as possible and the wheelbase as long as possible within the constraints of the vehicle package. Locate wheels at each of the extreme corners of the vehicle.
Use a fully independent suspension, and keep the contact patch location stable (minimal lateral movement).
Eliminate suspension and steering geometry errors. Go the extra mile for precession.
Establish the roll center according to the vehicle cg. If the cg is extremely low, the roll center may be at, or near ground level. The roll moment should be lower for extremely low mass vehicles.
Roll stiffness is essential for a low mass vehicles. If the vehicle understeers, place the anti-roll bar at the rear. If it oversteers, place the anti-roll bar at the front.
For increased traction, use wider rims and/or wider tires.
A torsionally rigid platform (frame) is essential for precise handling characteristics.
At freeway speeds, aerodynamic effects will be an important consideration, and aerodynamic effects increase as weight decreases. Consequently, the aerodynamic center of pressure should be as close as possible to the vehicle center of gravity. Eliminate lift, keep ground clearance minimal, angle the body slightly downward at the front.
