Suspension & Handling Calculators
Work through spring rate, sway bar stiffness, camber and caster, roll center height, and corner weight — the numbers that decide how a car turns, leans, and grips.
These suspension and handling calculators start from the same physics: spring force, arm geometry, and motion ratio.
From Spring Rate to Wheel Rate
A spring’s rate isn’t what the wheel actually feels. The suspension’s motion ratio — how much the wheel moves versus how much the spring compresses — changes that. Wheel rate equals spring rate times the motion ratio squared, so a motion ratio under 1 (common on most double-wishbone and strut setups) always softens the spring’s effective rate at the wheel. That wheel rate, combined with the car’s sprung weight at each corner, sets the ride frequency — the number most tuners actually target rather than a bare spring rate in lbs/in.
Sway Bars and Roll Stiffness
A sway bar doesn’t touch ride frequency at all — it only resists body roll by tying the left and right wheels together in cornering. Its rate depends on bar diameter to the fourth power, arm lengths, and the center section length, which is why a small increase in diameter changes stiffness far more than a small change in arm length. A stiffer front bar relative to the rear shifts weight transfer forward in a corner, pushing the car toward understeer; a stiffer rear bar does the opposite.
Frequently Asked Questions
Does a stiffer sway bar make the ride harsher?
Not directly. A sway bar only engages when the car rolls — one wheel moving up while the other moves down — so it has no effect on straight-line bounce frequency over bumps. Ride harshness comes from spring rate and damping, not bar stiffness.
Why does more caster make the steering heavier?
Positive caster creates a steer-centering effect: the greater the caster angle, the stronger the wheel’s tendency to return to center, which is felt as steering effort. That same effect is what makes a car with more caster feel more stable in a straight line.
Does adding negative camber always improve grip?
Only in the corner. Negative camber increases the tire’s contact patch while the car is leaned over in a turn, but it reduces contact patch — and straight-line grip and braking — when the car is upright. Setup is a trade-off between the two, not a one-directional gain.