Post by
Exar-Kun »
https://forums.nicoclub.com/exar-kun-u1725.html
Mon Aug 16, 2004 6:55 am
chris, you're right. Excessively stiff springs wont net you any gain in maximal cornering grip on the street, esspecially with street tires. you want some outer loading(as alan said), and for street driving, 3-5kg/mm is plenty stiff(50% to 150% stiffer than stock) depending on usage, tires, other mods, etc.
things people dont think fo also, is sway bars can act as springs, but in a different manner..the rule of thumb is that you dont want the sway bar controling body roll by more than 50%, bceause of its 'problems' versus stiffer springs, etc.
also, harmonics come into play of the human body, and you want the frequency to be about 1.5(IIRC) for oscillations, too much lower than that, the car will feel "like a marshmallow" to much higher and it feels like a rock.
other things to consider, a higher spring rate does more thanremove body roll, etc when you hit a bump, the wheels get pushed up, and via the spring thery push up on the body, the body, via gravity, pushes back down..forcing the spriing to compress, then push bac down on the suspension.
why is that important? because the ratio of sprung/unsprung weight and spring stiffness modifys how that process works.
the lighter the unpsprung assembly, the less work the spring has to do to keep the wheels in contact with the road(and the less you feel jounces on the road in the car body! bonus!)
this is one of the many reasons you hear people talking about the importance of unsprung weight savings.
this is also why if you lighten the chassis a lot, without lighteting the unsprung weight, you can get a much, much harsher ride feeling, with no change in spring rate.
and like fred noted, the ligheter the car, the stiffer the spring rate beacomes effectively, because there isnt as much weight to compress it.
*hew* forgive any tyops, I'm about to goto work.in a little bit of a rush, I'll come back and double check this tonight-chet
