Calculating vehicle inertia

Knowing the inertia of a vehicle, especially around the yaw axis is very useful for dynamic simulations such as ChassisSim. In this page we discuss how to calculate it, using some useful references.

Here below are some parameters, albeit for vehicles which are now quite old.

VEHICLE Wheelbase (m) CG loc (m) Inertia (kg*m^2) Mass (kg)

from fr axle above gnd Pitch Roll Yaw

1984 Audi Quattro 4000 2.520 1.124 0.506 2328 404 2352 1240

1986 BMW 325i 2.570 1.201 0.533 2011 381 2027 1251

1979 Datsun 280ZX 2.327 1.157 0.489 1948 360 2058 1295

1983 Honda Civic 2.235 0.827 0.519 1122 250 1216 879

1987 Mercedes 190E 2.664 1.22 0.550 2087 436 2142 1306

1985 Pontiac Fiero 2.375 1.389 0.507 1528 375 1619 1247

1986 Toyota MR2 2.319 1.3 0.500 1280 340 1460 1090

Inertia is calculated by taking the sum of the product of each point mass by its distance from the centre of gravity.

Click on this link to download a quick calculation tool: Vehicle Inertia Calculation Tool

Click on this link to download a guide for analytical and experimental calculations: Measuring the yaw moment of inertia of a vehicle

It is useful to consider the following ballpark figures:

RACE CAR

Dry mass with no driver (kg) 450-750 1300-1800

Wheelbase (m) 2.7 2.4-2.7

Yaw inertia (kg*m^2) 900-1150 1700-2500

Power (kW) 150-600 150-500

Power/mass (kW/kg) 0.3-0.8 0.15-0.3

Tyre adherence coefficient 1.3-1.7 1.0-1.1

Max gLong, gLat 2.5-4.5 1.1-1.3

CoG height (m) 0.23-0.28 0.35-0.55