I have a question for you guys.

So, in thinking about our quest to build faster race cars, I've run into what seems to be a paradox. We up the spring rates, and go faster--yet, when we consider spring rates in terms of Front vs. Rear, we equate softer rates to more traction, hence the front rates are lower than the rear. So, as the spring rates go up, does overall grip go down? are they in a sort of inverse tango like that? or is the key to "grip" as it relates to spring rates a function of the difference between front and rear rates/stiffness?

In thinking through why stiffer rears promote rotation, i've come to the conclusion that the load x-fer is more instantaneous with stiffer springs and the earlier loading of the rear tires takes them to the limits of grip before the fronts actually get there (since the spring is busy being displaced and everything).

continuing then to overall dynamics, if stiffer springs mean quicker load x-fer, how does that relate to corner entry speeds/exit speeds? is it simply a function of roll resistance? is it that the time (t) it takes for the tires to reach the limit of traction decreases, but the work done by the tires/car is done more efficiently? (if it's even considered "work" aka /F dx)

i've experienced life on stiffer springs IRL, and so i know they work, but i guess i'm just trying to fully wrap my brain around how, and as much fun as it is to try and understand "Tune to Win" i guess what i'm asking for here is a one-off tutor.

beefy question i know, but TIA.

 

Great topic. I'll bite.

It's not a rate (t) issue - that's for a seperate talk about damping. You're talking about steady-state cornering here. Stiffer springs make car handle better because less roll wich means less transition and the tire contact patch is more square with the road. Balance in a steady corner is dermined by the ratio F/R of spring rates and sways bar stiffness - and basically the stiffer end is going to work the outside tire more because it will handle more of the load, and thus give out earlier. Make sense?

I see your pdx - you say, I make the front softer and it sticks more. Not quite, by making the front softer you make the rear work harder, and the rear sticks less. Why is it good to have the rear stick less? To get the thing to rotate. QED.