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Shock Absorber Calculator

2026-09-27 6 min

Damper force and dissipated power from damping coefficient and shaft velocity.

Damper Force
350 lb
Power Dissipated
0.53 hp
Heat into the damper

Calculator

Damping Coefficient(lb-s/in) Help
lb-s/in

Low-speed slope of dyno curve

Shaft Velocity(in/s) Help
in/s

Bumps 5-20, hits 50+ in/s

Results update live as you type

Live statistics

Damper Force

350 lb

Power Dissipated

0.53 hp

Heat into the damper

Results

Optimal

Damper Force

350lb

Power Dissipated

0.53hp

Heat into the damper

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

Visualizations

Results overview

350Damper Force
0.5Power Dissipated

Damper Force vs. Damping Coefficient

Damper Force

350lb
02,000

Formula

Linear damper model plus the heat it makes — the reason shocks fade on rough stages.

Force = coefficient x velocity

Alternative Form

Power hp = force x velocity / 6600 (in-lb/s per hp)

Variables

SymbolNameUnitDescription
cCoefficientlb-s/inDyno slope
vShaft speedin/sBump severity

Explanation

Dampers are heaters with a job: kinetic energy becomes oil heat — sustained rough use boils small shocks.

Step-by-Step Calculation

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

Step 1

Record the inputs.

Damping Coefficient:35 lb-s/in
Shaft Velocity:10 in/s
Result: 2 inputs ready
Step 2

Apply the formula.

Force = coefficient x velocity
Result: Primary result = 350 lb
Step 3

Read every derived output.

Damper Force:350 lb
Power Dissipated:0.53 hp
Result: Damper Force = 350 lb
Final Answer
350

Worked Examples

See how the calculator works with different scenarios.

Scenario

Mid-corner bump hit.

Inputs

Coefficient:35
Velocity:10 in/s

Calculation

F = 350 lb; power = 0.53 hp

Result

350-lb force, ~0.5 hp of heat.

Interpretation

One corner, one bump — multiply by four corners of washboard and heat adds up.

Understanding Your Result

Your Result: Damper Force: 350 lb

What This Means

Force the damper contributes at a given shaft speed.

Why It Matters

Reads shock-dyno curves as on-car forces and explains fade.

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

Dampers convert motion to heat at force proportional to speed.

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

  • •Size reservoirs for sustained rough use
  • •Dyno-match pairs per axle
  • •Heat shields near exhausts and brakes

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.

Why do shocks fade?
Oil overheats and thins (or aerates) — force drops. Remote reservoirs add oil volume and cooling.
Linear vs digressive valving?
Linear builds force with speed; digressive plateaus — firm body control without harshness on sharp hits.

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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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