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Engine Tuning and Chassis

Suspension Ride Frequency Calculator

Estimate undamped corner ride frequency from wheel rate and sprung mass. Tire stiffness, damping, coupled body modes, motion-ratio variation, and anti-roll bars are omitted.

Enter compatible measurements

Record physical measurements under repeatable conditions whenever possible.

lb/in

Effective vertical wheel rate.

lb

Corner weight supported by the spring, excluding unsprung mass.

Hz

Reference value for comparison.

Before interpreting the answer

Estimate undamped corner ride frequency from wheel rate and sprung mass — vehicle mass, gearing, traction, temperature, and aerodynamic conditions can change the observed result.

Tire stiffness, damping, coupled body modes, motion-ratio variation, and anti-roll bars are omitted — that condition defines when estimated ride frequency is comparable with another result.

For a second calculation that will calculate one wheel position as a percentage of total vehicle weight, use the Corner Weight Percentage.

How the quantities interact

The Wheel rate entry represents effective vertical wheel rate — before calculating, use a measurement or specification from the exact component and operating condition being evaluated.

Sprung mass at corner: Corner weight supported by the spring, excluding unsprung mass — a compatible entry should use the same loaded condition for every weight and retain the scale ticket or rating source.

For Target ride frequency, use the quantity described as reference value for comparison — in the vehicle record, use a measurement or specification from the exact component and operating condition being evaluated.

ride frequency = 1 ÷ 2π × square root(wheel rate ÷ sprung mass)

In “ride frequency = 1 ÷ 2π × square root(wheel rate ÷ sprung mass),” the printed units define how each term is interpreted.

No term beyond wheel rate, sprung mass at corner, and target ride frequency is introduced in “ride frequency = 1 ÷ 2π × square root(wheel rate ÷ sprung mass).”

An example with recorded units

To trace the arithmetic, start with Wheel rate = 180 lb/in, Sprung mass at corner = 750 lb, and Target ride frequency = 1.5 Hz.

After applying the formula, the displayed results are Estimated ride frequency = 1.53 Hz, Difference from target = 0.03 Hz, and Wheel rate in N/m = 31,523 N/m.

Putting the number in context

Estimated ride frequency answers “Estimate undamped corner ride frequency from wheel rate and sprung mass.” The additional displays, Difference from target and Wheel rate in N/m, are a different view of the same entered measurements.

Use the result only as one suspension-design reference — when that condition changes, compare separate calculator runs instead of blending the inputs.

Because tire stiffness, damping, coupled body modes, motion-ratio variation, and anti-roll bars are omitted, a disagreement between estimated ride frequency and an outside reference should trigger a review of wheel rate and target ride frequency.

What requires independent verification

Traction, grade, wind, temperature, driver input, and control-system intervention remain outside this simplified model — for target ride frequency, the page specifically expects reference value for comparison.

How to document the calculation

Choose a controlled operating condition and record the setup before comparing a second run — this workflow must also account for the fact that tire stiffness, damping, coupled body modes, motion-ratio variation, and anti-roll bars are omitted.

  • Record Wheel rate as effective vertical wheel rate — use a measurement or specification from the exact component and operating condition being evaluated.
  • Record Sprung mass at corner as corner weight supported by the spring, excluding unsprung mass — use the same loaded condition for every weight and retain the scale ticket or rating source.
  • Record Target ride frequency as reference value for comparison — use a measurement or specification from the exact component and operating condition being evaluated.
  • Repeat the check only after accounting for this condition: tire stiffness, damping, coupled body modes, motion-ratio variation, and anti-roll bars are omitted.

The current equation stops before the step needed to estimate injector mass-flow requirement from power, BSFC, count, and duty cycle, which is handled by the Fuel Injector Flow Rate.

Clarifying the calculation

What measurement source fits Wheel rate when it represents effective vertical wheel rate?

Because wheel rate represents effective vertical wheel rate, use a source tied to the exact vehicle, component, and operating period described by the other fields.

How does the warning “Tire stiffness, damping, coupled body modes, motion-ratio variation, and anti-roll bars are omitted” affect Estimated ride frequency?

The condition “Tire stiffness, damping, coupled body modes, motion-ratio variation, and anti-roll bars are omitted” is not corrected automatically by the numeric inputs, so create a separate suspension ride frequency case when it changes.

What assumption is expressed by “ride frequency = 1 ÷ 2π × square root(wheel rate ÷ sprung mass)”?

In “ride frequency = 1 ÷ 2π × square root(wheel rate ÷ sprung mass),” wheel rate and sprung mass at corner are treated as parts of one vehicle case.

How narrowly is Sprung mass at corner defined by “Corner weight supported by the spring, excluding unsprung mass”?

The definition “Corner weight supported by the spring, excluding unsprung mass” excludes a similarly named rating or a measurement taken at another reference point.