Quote:
Originally Posted by Ladogaboy
Rotational weight, especially in the reference to performance vehicles, usually is considered separately from standard... "sprung"... weight reduction.
|
Pedantry follows:
Sprung mass is anything that is supported by the suspension springs. The seats, the engine, almost all of the car is sprung mass. Some of the things that make up that sprung mass also rotate, such as the engine's crankshaft, the flywheel, etc.
Unsprung mass is anything that is not supported by the springs of the suspension. Things like the wheels and tires, the brake calipers, and so on. Obviously much of that mass does rotate (wheels, tires, brake rotors), but some of it does not (brake calipers, the housing of a live rear axle).
Some parts are partly sprung, like the springs themselves, suspension arms, and drive shaft(s).
Car makers generally try to reduce unsprung mass as much as they reasonably can, as it tends to have a sizeable effect on the ride quality of a vehicle.
-soD