Does stiffness really mean more responsive behaviour?

[KSaiyu]

bah, I thought I'd stopped with these handling questions monthes ago, but with GT4 coming and the fact that I just got my license, I'm curious again

I've always taken for granted that a stiffer car will be more responsive and have quicker turn-in than an equal car that isn't as stiff, it just seemed logical. But know I've been wondering - is this the case? I know that the stiffer car will transfer weight quicker - but I'm not sure if that fact is relevant to the responsiveness of the car. And since the "softer" car will transfer the weight more gradually from inside to out wouldn't this result in a better handling car during turn-in, meaning a more responsive car (unfortunately I don't have the driving experience to compare)?

So I guess I wanna know - why does more body roll mean (if it does) wallowy, sluggish turn in and a stiffer car quicker respones?

Thanks for your time once again

 

[TheCracker]

A stiffer car, like you mentioned, will transfer weight from one side to the other quicker - therefore settling the 'balance' of your car much quicker and also you will get less weight transfer to the 'outside' edge of the car keeping the centre of gravity more central which will again be benifitial to turn-in. Because the car's weight is shifted less to the 'outside' and kept more central, all four tyres will share the load more evenly which inturn increases overall grip. A stiffer set up distributes the cars cornering 'loads' much more evenly than a softer set-up that will store up more kenetic energy in the outer springs/dampers.

To keep it simple, body-roll puts more weight on the outside tyres of the car, which means two of your tyres are doing most of the work whilst the inner two do very little.

Anti-roll bars stop one side of the cars suspension from doing all the work by connecting the left and right-hand suspension arms to each other and to the chassis, which gives 'stiffness' without hampering 'suppleness' like stiffer springs/dampers would.

These measures help track-cars a great deal, but can make a road car too uncomfortable on normal roads - a performance road cars set-up is always a case of compromise.

Hope this helps a little, but i'm no engineer!

 

[///M-Spec]

I think TheCracker summed it up pretty nicely.

Where you really see spring/shock stiffness pay off is in a transitional handling situation like an emergancy lane change manuver or a slalom. The simple fact of the matter is because weight takes less time to shift, your tires are generating peak grip faster, allowing for more instantaneous response.

Other factors that affect transiant response is tire sidewall stiffness, inflation pressure, suspension geometry, and bushing stiffness. And the steering rack itself, of course.

In a steady-state situation, however --such as long sweeping turn-- once the car has taken "a set", roll stiffness doesn't play that much a role in response anymore. The download has already been distributed and the cornering attitude of the car is established.


M

 

[KSaiyu]

Thanks for both of the explanations, that did clear it up. I also read up and discovered I didn't take camber/contact patch changes due to roll into consideration as well.

stiffer set up distributes the cars cornering 'loads' much more evenly than a softer set-up that will store up more kenetic energy in the outer springs/dampers

But wouldn't the kinetic energy be the same in both the stiffer and softer set up springs/dampers - only the amount of movement by the suspension would change, or does the increased body roll mean more kinetic energy?

 

[TheCracker]

But wouldn't the kinetic energy be the same in both the stiffer and softer set up springs/dampers - only the amount of movement by the suspension would change, or does the increased body roll mean more kinetic energy?

The stiffer set-up would distribute the load more evenly. 👍

 

[PublicSecrecy]

The rigidity of the body and chassis also plays a huge role. As do steering ratio, for overall handling anyway.