why do cars have body roll

[MaFi0s0]

i was wondering why some cars (especially family sedans) have so much unnecessary body roll, and i dont mean the older ones where the suspension and shocks are worn out, some new cars even have abit of body roll, and im wondering what good can body roll do for a car.

[MBTN]

This is because the shocks are soft. There is always a trade off. The car may roll in turns, but the ride will be very smooth, especially in something like a Benz. Sports cars use stiffer suspension because they need to be nimble. Something like a Ferrari has body roll as flat as Nebraska, but the ride would be harsh and every little bump will be felt.

[MaFi0s0]

i thought strut bars where to decrease body roll without having hard suspension

[MBTN]

True. Other similar things called torsion bars or sway shafts. When the outside suspension is compressed during a turn, the bar will compress the inside suspension too.

[texan]

Cars have body roll due to physics, and nothing else when it really comes down to it. If the roll center of an axle (defined as the point about which the suspension geometry will rotate) is below the Cg (Center of Gravity, or the point about which a vehicle's motion is dentered), the forces acting upon the vehicle in a turn cause it's body to roll outwards. Think of the distance between these two virtual points as a lever, and if the Cg is higher than the roll center, the lever swings outwards toward the edge of the turn.

Since no current vehicle technology can get the roll center of any given axle below the Cg height of a car, they always roll out of the corner. If you were to make a workable suspension design with the roll center above the Cg, your car would actually roll INTO the turn, motorcycle style, and not out of it.

Modern suspension designs add anti-sway bars to counteract some of this inherent body rolling. Different cars have different tendencies toward roll, and there are many other factors involved, but the most effective means to stop excessive rolling is through proper sway bar sizing. Since large sway bars do havea negative impact on suspension performance, and family cars have a limited need for serious cornering abilities, you'll find that modestly sized sway bars are fitted to them and as such they roll quite a bit during cornering. Spring rates also have a great deal to do with this, but if you want more in depth informaiton you can always check out my article on swaybars and how all this basically works. Go here. Peace.