Race Engineering: Method for measuring unsprung mass on a race car.

Here is a practical method for measuring unsprung mass on a race car.

Method:

  1. Corner weight car. Recording total mass on each corner.
  2. Raise the car 2 or 3 inches (40-60mm) –> Jack on unsprung area
  3. Disconnect one end of spring damper –> Use spring clamps (preload – be careful)
  4. The scales should show the unsprung mass at each corner –> minus or add half spring damper
  5. For each corner calc sprung mass –> take the unsprung mass from the original total mass.

Consider / Remember:

  • Suspension joint friction –> Try freeing up
  • Live axle implications –> If any
  • Contribution of the spring damper in the calculation –> Take half its weight and correct figures
  • Driver weight –> Should include

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