Suspension stiffness and handling....
04-12-2005, 04:13 AM
#31
Race Director
Oh, I realized I didn't make it clear, there's a cause and effect relationship here that's often confused. The "cause" is the lateral cornering force generated by the front-tyre moving at a non-parallel angle to the direction of travel. This pulls the front-end over from straight-ahead and the rear tyres are now not parallel to the direction of travel...HOWEVER... Newton's laws state that the mass will want to travel in a straight line unless acted on by an external force. So... the car wants to go in a straight line, but the tires are pushing in from the outside... the car carves a curve:
The "effect" of this, or result... is that the mass of the still goes in a straight line and that weight is transfered onto the outside tyres, because they are now in the path of that straight-line trajectory the car was headed in. The tighter the corner, the greater the speed, the higher the C.O.G is, the more weight is transfered to the outside tyres. The suspension then compresses due to this extra weight on the outside tyres. The amount of lean is proportional to the suspension stiffness, however the lateral-weight transfer that's the "cause" of the lean is only dependent upon the cornering-G, the C.O.G. height and the track-width.
Since you can't affect the cause, you can however, mitigate its effect. A stiffer suspension will keep the car flatter, and thus the tyres flatter on the ground for the same amount of cornering force (at least on our cars). With well-designed double-wishbone suspensions however, you can actually over-spring the car. Due to the well-calibrated camber-change curve based upon all the design parameters, if you stiffen up a double-wishbone suspension too much, it ends up compressing without leaning and can actually end up with TOO MUCH negative camber...
The "effect" of this, or result... is that the mass of the still goes in a straight line and that weight is transfered onto the outside tyres, because they are now in the path of that straight-line trajectory the car was headed in. The tighter the corner, the greater the speed, the higher the C.O.G is, the more weight is transfered to the outside tyres. The suspension then compresses due to this extra weight on the outside tyres. The amount of lean is proportional to the suspension stiffness, however the lateral-weight transfer that's the "cause" of the lean is only dependent upon the cornering-G, the C.O.G. height and the track-width.
Since you can't affect the cause, you can however, mitigate its effect. A stiffer suspension will keep the car flatter, and thus the tyres flatter on the ground for the same amount of cornering force (at least on our cars). With well-designed double-wishbone suspensions however, you can actually over-spring the car. Due to the well-calibrated camber-change curve based upon all the design parameters, if you stiffen up a double-wishbone suspension too much, it ends up compressing without leaning and can actually end up with TOO MUCH negative camber...
