Hi all! This question has been on my mind for some time now. Anyway, to give the basic idea, if say the car's springs are set at 90F and 110R in Neuton meters. If say I want to stiffen the front to 120 and then calculate the ratio between the original settings (90/110= 0.82 or front is 82% of the rear) so then I divide 120 by 0.82 to give me 146 for the rear stiffness. Is this a plausible method to maintaining the handling characteristics of the setup but would obviously amplify the setup's understeer/oversteer tendency.

I know a major factor of setup is also feeling but the general rule is to make the car stiffer to get faster lap times. Also, does this method of calculation apply to other parts of setup (downforce, dampers and (maybe) camber and toe). Thanks.

In a word, no. You need to look at the effects at the wheel - i.e. the wheel rate, rather than the spring rate. Bob's already done all of that, so just use his Vehicle Analyser if you don't want to work stuff out yourself.