For the mass moment of inertia θred, the following moments of inertia of the drive train have to be considered:
Motor, clutch : θeng + θC
Transmission with specific ratio i : θTi
(referred to the transmission input shaft)
Drive shaft, differential : θdr
Wheels (mostly including brake drum or brake : θW
disk and axle shafts)
In the consideration of the mass moment of inertia of the wheels, attention has to be paid to the fact that all wheels of the vehicle have to be considered, regardless whether the front wheels, rear wheels, or all wheels are driven.
Considering the ratios in the transmission iTi (for the particular gear) and the axle transmission ir(f) (for rear- and front-wheel drive) we arrive at the mass moment of inertia reduced to the drive axle for a gear i. The dynamic equality of output and replacement system is to be maintained.