Suspension Questions

[Suspension Guy]

I was recently reading a book about suspensions which raised some questions in my mind. What are acceptable roll rates, tire vertical rates, roll gradients, and front and rear ride frequencies for a FSAE car? Thanks for any help, it is appreciated!

[Suspension Guy]

I was recently reading a book about suspensions which raised some questions in my mind. What are acceptable roll rates, tire vertical rates, roll gradients, and front and rear ride frequencies for a FSAE car? Thanks for any help, it is appreciated!

[Suspension Guy]

Sorry for the double... got confused!

[Jeff Curtis]

I don't think there is one answer to this question. I know for one the Cornell car has been sprung differently in different years and has won both ways. I think a car with a roll gradient of .75 to 1 deg/g is a safe bet. I also believe that there should be a slightly higher rear freq. then in the front for ride. Anywhere from 2.25 to 3 Hz is safe. The damping is probally more critical than the exact ride frequency. Research what damping ratios are ideal for ride and performance in the Shock Absorber Handbook. Then work to achive those requirements by re-valving or re-shiming what ever shocks you are using.

Remember, your car is a system, don't forget how the roll and pitch gradients are going to react with your suspension geometry! Never design anything without fully understanding the tires you are using.

Jeff