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Racing Suspension Calculator

2026-09-27 6 min

Wheel rate and spring rate from corner weight, motion ratio and ride-frequency target.

Wheel Rate
347 lb/in
Spring Rate
480 lb/in

Calculator

Corner Weight(lb)
lb
Motion Ratio Help

Wheel travel / spring travel

Target Frequency(Hz)
Hz
Results update live as you type

Live statistics

Wheel Rate

347 lb/in

Spring Rate

480 lb/in

Results

Optimal

Wheel Rate

347lb/in

Spring Rate

480lb/in

Planning estimate from standard automotive formulas. Validate with dyno, timeslip or datalog data when precision matters.

Visualizations

Results overview

346.5Wheel Rate
479.6Spring Rate

Wheel Rate vs. Corner Weight

Wheel Rate

346.5lb/in
01,000

Formula

Ride-frequency physics gives wheel rate (386 in/s2 gravity); motion ratio converts it to spring rate.

Wheel = (2 pi f)^2 x (corner / 386); spring = wheel / MR^2

Variables

SymbolNameUnitDescription
fRide frequencyHzTarget suspension frequency
MRMotion ratioratioWheel motion per unit spring motion

Explanation

700 lb at 2.2 Hz needs ~347 lb/in at the wheel — ~480 lb/in springs through a 0.85 motion ratio.

Step-by-Step Calculation

Follow each step to understand how the result is calculated from your inputs.

Step 1

Record the inputs.

Corner Weight:700 lb
Motion Ratio:0.85
Target Frequency:2.2 Hz
Result: 3 inputs ready
Step 2

Apply the formula.

Wheel = (2 pi f)^2 x (corner / 386); spring = wheel / MR^2
Result: Primary result = 347 lb/in
Step 3

Read every derived output.

Wheel Rate:347 lb/in
Spring Rate:480 lb/in
Result: Wheel Rate = 347 lb/in
Final Answer
347

Worked Examples

See how the calculator works with different scenarios.

Scenario

700-lb corner, 0.85 motion ratio, 2.2-Hz target.

Inputs

Corner:700 lb
MR:0.85
Freq:2.2 Hz

Calculation

Wheel ~347 lb/in; spring = 347 / 0.7225 = ~480 lb/in

Result

~480 lb/in springs.

Interpretation

Buy the nearest stocked rate, then fine-tune with bars and dampers.

Understanding Your Result

Your Result: Wheel Rate: 347 lb/in

What This Means

Spring stiffness that delivers a chosen ride frequency.

Why It Matters

Frequency-based setup transfers between cars — rates do not.

Professional Interpretation

Treat the primary result as a planning estimate, then validate on a dyno, at the track, or with logged sensor data. If measured numbers disagree by more than ~10%, re-check inputs (units are the usual culprit) before changing parts.

Recommendations

  • •Double-check units on every input before trusting the result
  • •Compare against the worked example below to sanity-check magnitude
  • •Validate with measured data (dyno, timeslip, datalog) when it matters

Learn — fuel economy, deeply

Suspension setup starts from ride frequency, not spring catalog numbers.

1 · Where the gallon goes (energy path)

Engine heat

60–70% lost

Coolant + exhaust carry most energy away. Hybrids recover some via Atkinson cycle + regen.

Driveline

5–15% lost

Transmission, differential, accessories. CVTs and 8–10 speed autos lose less.

Aero drag

∝ v²

Doubles from 55→78 mph. Roof boxes hurt more than trunks.

Rolling + brakes

10–20%

Tires, weight, stops. Regen braking (hybrid/EV) reclaims city braking energy.

4 · Measure like a pro (the 3-tank protocol)

  1. Fill to first click at the same pump, record the odometer (Tank 0).
  2. Drive normally for 2–3 tanks; always refill to first click at the same pump.
  3. MPG = total miles ÷ total gallons across all tanks — averaging kills pump-click noise.
  4. Cross-check with the trip computer; a persistent >10% gap means the computer needs calibration — or the car needs service.
  5. Log with an OBD-II dongle for per-trip MPG if you want to isolate commute vs. highway behavior.

Practical Tips

  • •Start 2.0-2.5 Hz for sprung aero-light track cars
  • •Rear frequency usually 10-20% above front
  • •Motion ratio errors square — measure it carefully

Common Mistakes

Mixing units (inches with mm, psi with kPa)
Convert every input to the unit shown on its field before calculating.
Trusting a single output blindly
Cross-check with the worked example and, when it matters, a dyno or datalog.

Assumptions

This calculator makes the following assumptions to provide estimates:

Steady-state model: Formulas assume stabilized conditions; transients, heat soak and traction limits are excluded.
Standard factors: Empirical constants (BSFC, VE, drivetrain loss) use typical values — your combination may differ.

Limitations

Be aware of these limitations when using this calculator:

Estimate, not measurement: Predictions carry real-world scatter of roughly ±5–15% depending on the model.
No transient effects: Shift time, wheelspin, spool lag and heat soak are not modeled here.

Frequently Asked Questions

Answers to common questions about this calculator.

What frequency should I target?
Roughly 2.0-2.5 Hz for track cars without big aero; downforce cars run 3+ Hz.
Why divide by motion ratio squared?
Leverage works twice — once on force, once on travel — so the correction is MR squared.

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Related Guides

Deepen your understanding with these educational resources.

Glossary

Technical terms used in mortgage calculations explained in plain language.

MPG
Miles per gallon. Distance travelled per gallon of fuel; higher is better. US gallon = 3.785 L.
L/100 km
Litres consumed per 100 kilometres; lower is better. Standard metric efficiency unit.
MPGe
Miles per gallon-equivalent. EV metric: miles travelled on 33.7 kWh (energy of 1 gal of gasoline).
CAFE
Corporate Average Fuel Economy — US fleet-average efficiency standard enforced by NHTSA.
Rolling resistance
Energy lost deforming tires as they roll. Low-pressure or wide tires raise it.
Aerodynamic drag
Air resistance growing with the square of speed — why highway MPG falls fast above 60 mph.
Hypermiling
Driving techniques (coasting, steady speed, anticipation) that maximise real-world MPG.
OBD-II
On-board diagnostics port. Scanners and dongles read live MPG, fuel trim and fault codes.

Authoritative References

Trusted sources and standards referenced by this calculator.

Applicable Standards

EPA Fuel Economy Testing (40 CFR Part 600)CAFE — Corporate Average Fuel Economy Standards (NHTSA)WLTP — Worldwide Harmonised Light Vehicle Test ProcedureSAE J1321 / J1711 — Fuel consumption test proceduresISO 2575 — Road vehicles symbols & efficiency markings

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