SUSPENSION GEOMETRY CALCULATORS
Seven calculators for the geometry behind steering feel, grip and body control. Drag the sliders or type measurements from your own car. The numbers each tool opens with are examples, not specifications for any vehicle, and the results are estimates from simplified geometry.
Each tool has a matching guide in Stance Science. These setups are not saved to your account yet; note your numbers before leaving the page.
ACKERMANN
Ideal outside wheel angle for a given inside angle, and the Ackermann percentage of a measured pair.
RESULT
Measured outside wheelIdeal: both wheels aimed at one turn center
TOE CONVERTER
Convert toe between degrees and a distance measured across a known diameter. Works for total or per-wheel toe, as long as both sides of the conversion use the same one.
Angle to distance
Distance to angle
RESULT
The drawing exaggerates the angle twelve times. A 17" rim is 432mm across, 18" is 457mm, 19" is 483mm; the same angle measured across the tire tread gives a larger distance.
CASTER, TRAIL AND CAMBER
Mechanical trail from caster, the camber each front wheel gains when steered, and how far added camber moves the tire at fender height.
Camber at the fender
RESULT
Steering axis and where it meets the roadCenter of the contact patch
camber change ≈ KPI × (1 − cos(steer)) ∓ caster × sin(steer)
The camber figures are a small-angle estimate and ignore body roll and suspension travel. How camber is adjusted decides the pivot: a longer lower arm pushes the bottom of the tire out instead.
SCRUB RADIUS CHANGE
How far a wheel, spacer or tire change moves scrub radius. The change needs only the two setups; the absolute figure needs the car's original scrub radius.
Tires
If known
RESULT
New tireCurrent tireSteering axisThe current tire is placed using the original scrub radius entered.
MOTION RATIO AND WHEEL RATE
Turn a spring rate into the rate at the wheel, the ride frequency for that corner, and the spring needed to hit a target frequency.
Target
RESULT
This setupTargetThe bands are a rough guide. Tire stiffness and anti-roll bars are not included.
frequency = (1 ÷ 2π) × √(wheel rate ÷ sprung mass)
ROLL CENTER
Static roll center height from pivot points in front view, measured at standard ride height. The ride height slider then lowers the body-side points to show what a drop does.
Lower arm inner pivot
Lower arm outer pivot (ball joint)
Upper arm inner pivot
Upper arm outer pivot
RESULT
Roll centerContact patch to instant centerWhere the two teal lines cross the centerline is the roll center.
ANTI-DIVE AND ANTI-SQUAT
Percentages from the side-view instant centers. Find each instant center by extending the suspension links in side view until they meet.
Front, under braking
Rear, under power
The car
RESULT
Front, under braking
Rear, under power
Force line to the instant center100% anti-squat lineThe front calculation assumes outboard brakes.
anti-squat % = tan(angle) ÷ (CG height ÷ wheelbase) × 100