Influence of anti-roll bars on spring stiffness calculations

Hi, in a section of choosing springs...we learned spring rate is calculated based of our desired suspension frequency, sprung mass and motion ratio. I am wondering if we should also take into equation anti-roll bar stiffness? So with other words...should be desired stiffness a sum of spring & bar, or should we ignore anti-roll bar?

Hi Vito, no we don't want to account for the ARB stiffness in this calculation. What we're really wanting to consider here is the natural frequency of the suspension when assuming a corner in isolation, or alternatively if we look at the front axle line and consider both wheels negotiate the same magnitude bump, in which case the ARB has no affect on the frequency. Yes of course the ARB comes into play during body roll or when one wheel transitions a bump and the other doesn't but that is a separate case.