Why is unsprungmass negative?

[Marst]

Would anybody be kind enough to explain in what point unsprung mass has negative effect on race car dynamics. Thanks.

[Rogue230]

I'll post an answer over the weekend.

[Rogue230]

Unsrung mass has the effect of transfering road-shock to the car. It has inertia and doesn't want to respond to changes in the road.

Also, it slows the tires downward return to the pavement causing a potential loss of contact with the road.

Consider a go-cart; All mass is unsrung and all road irregularities are tranfered directly to the car.

If it were possible to have 0% unsprung mass the tires would quickly respond to road changes and return downward without delay giving a virtually perfect ride.

Seeing as perfect isn't possible, minimizing unsprung mass is highly desirable.

[Micky]

What exactly is unsprung mass?

[Rogue230]

Sprung mass is everything riding on the springs; the body, engine, trans-axel.

Unsprung mass is that which the springs ride on; tires, wheels, out-board brakes.

Some parts are a mix; A-arms are 50-50. Half sprung and half unsprung, effectively.