the chassis height and C/G

[Karam El Hady]

what is the optimum clearance between the lowest member in chassis and the ground ?
Is 80mm a good clearance ? and if i make the clearance lower is that will make the C/G lower ??

[Bemo]

If you reduce the ground clearance by reducing the ride height and leaving everything else as it is, obviously the CG will drop by nearly the same amount as you lower the Chassis (a bit less as the unsprung weight will stay where it is).

In General you want the ground clearance to be as low as possible while making sure your car doesn't hit the ground while driving. How much ground clearance you Need to achieve this? Well it's up to you to find out ;-)

[Jonny Rochester]

80mm is generous clearance for a good FSAE car, as 100mm clearance is the legal requirement for road cars.

"Optimum" clearance is 57.367mm, from chassis to ground.

Then your underbody aero takes up half that gap and scrapes along the ground.

[Forbes]

"Optimum" clearance is 57.367mm, from chassis to ground.

Jonny: Where did that number come from?

Forbes

[Jonny Rochester]

I pulled that number out of thin air. He wanted a number, I gave it to him. But 57mm wouldn't be such a bad place to start.

[MCoach]

I pulled that number out of thin air. He wanted a number, I gave it to him. But 57mm wouldn't be such a bad place to start.



Build the car, stand in it, jump up and down to jounce it (with a calibrated 80kg human). If the car bottoms out before the limit of travel it is too low, if it does not, it is too high.

57mm is an unfair number as it should be a function of your suspension stiffness. So it's more like 57mm - (K / 500) +/- M where K is kg/mm of wheel rate and M is 5mm and positive or negative depending on if the driver's helmet visor has been properly de-fogged.