A question about Stiffness

[Jarod.Yi]

Hertz was frequently used in the manual to describe suspension stiffness
, while kN/m is what's actually used in the game. What's the relation between these two?:schwitz:

[danowat]

Its the spring frequency, if you use colcob's suspension analyzer you can get the figure from there.

There must be a way to work it out using the spring rates, but I havent got that forumla.

Dan,

[Shotglass]

take the mass of the car, substract the unsprung mass (should be somewhere in the setup guide), multiply that with the weight distribution, divide by two to get mass per spring and calculate the frequency via f = (1/(2*pi))*sqrt(k/m) with k being the spring constant and m the mass you previously calculated for that wheel

$f = \frac{1}{2\pi} \sqrt{\frac{k}{m}}$ in case you know tex

[danowat]

take the mass of the car, substract the unsprung mass (should be somewhere in the setup guide), multiply that with the weight distribution, divide by two to get mass per spring and calculate the frequency via f = (1/(2*pi))*sqrt(k/m) with k being the spring constant and m the mass you previously calculated for that wheel

$f = \frac{1}{2\pi} \sqrt{\frac{k}{m}}$ in case you know tex

Or use the suspension analyzer :nod::D

Dan,

[Spies]

Looks like I'm going to be the immature one and s****** at the thread title.

[Shotglass]

Or use the suspension analyzer :nod::D

is the s2 analyzer released yet ?

[danowat]

Not sure, I have just been using the latest FXO one recently.

Dan,

[Bob Smith]

You can just change the car data from the S1 setup analyser and at least the suspension/damping pages will work correctly. Just ignore the camber bit.

[colcob]

is the s2 analyzer released yet ?

*coughs*

No, and I've no idea when it will be. I did have big plans for it and started work quite a while ago, but life took over. I've got a big job on at work which doesnt finish till july/august and I'm building an extension on my house. So it wont realistically get done till after one of those things is finished.

But to the original questioner, the value of spring stiffness in the setup screen is the actual physical value. But the way that spring behaves depends on how much weight is sitting on it. So to get a balanced car behaviour, you need the stiffness of the springs to match the weight distribution of the car.

But its not just linear, so you cant take a car with say 60/40 weight distribution and make the front springs 60kN/m and the rears 40kN/m.
But what you can do is make the suspension frequency the same, which is the speed at which one end of the car would bounce up and down if it had no damping.

So in a way, suspension frequency is a more flexible way of referring to suspension stiffness between cars, as it is independent of the mass of the cars.