With a stiff suspension, there's less movement from the car in a turn, The majority of the "force" is placed on the tires, therefore the tires will break loose quicker. With a soft suspension the car will roll more, the suspension will travel more, essentially the car will be absorbing more of the force which allows the tires a better opportunity to grip.

 

Thats exactly what I thought, thanks!

But what does this mean in terms of companies who actually R&D their products? Is it simply that KW has done the research to determine how stiff is too stiff and they have applied this knowledge to their coils? And that BC has just thrown together some stiff springs and shocks and called them coils?

 

Diggressive means that the curve starts out steep at low values, then flattens out at high. For shocks, it means that you get a higher critical damping rate for low speed movements (ie body roll and pitch), and lower critical damping rate for high speed movements (ie bumps), which is what you want.

Everyone knows this, but making good shocks with good properties (and low hysteresis) isn't cheap. It's much easier to make linear shocks, then market them well. So the cheap linear shocks usually match the low speed damping, but then don't drop off for the high speed damping, so you get a needlessly harsh ride, which people take as being evidence of a "sports" suspension. They also many times have high compression damping rates, which makes the car feel more nimble, because it decreases the response time from when you turn the wheel to when the car moves, because it transmits the forces faster before the car completely settles on the springs. But this is minimally useful on a track, because you usually already compressing your front tires with hard braking, and then gradually rolling to the side as you gradually get off the brakes. When you have too much low speed compression, your car feels responsive, but, from penske, "A car with too much low speed damping will usually lack grip in change of directions, cannot put power down in
slower corners (wheel spin) and lack overall grip after initial turn in."

further reading:
http://farnorthracing.com/autocross_secrets6.html
http://www.optimumg.com/docs/Springs...Tech_Tip_4.pdf
http://www.penskeshocks.com/files/Adjustable_Manual.pdf

Don't think many people use fortune auto, but the few graphs out there i thought showed they were pretty linear. Bilsteins are good value because they are a huge company, and can reuse many parts.

It's not really a secret what makes good dampers, its just that doing it costs money and has to have a good degree of manufacturing precision. I think part of it is the nature of the import car scene. The vast majority of the kids who modify their car don't track regularly. Even those that track regularly don't necessarily know what is good in terms of performance. So people go by their subjective feel, which is completely uninformed. But when people buy a set of coilovers, then slap them on their cars, they expect a difference in how the car drives. I think that's probably why bilstein/konis aren't that popular, because they don't feel that much different. So people throw some ridiculously high damping rates on cheap linear shocks, with cheap springs, knowing probably full well it sucks for performance, but the consumers gobble them up because they feel sporty, look shiny, and have all the bells and whistles, and are affordable.

you should reconsider your idea about getting and adjustable damper. unless you can test it on the track and are a pretty awesome driver(like professional level), or have a shock dyno, you probably don't know what is good. But if you must, a set of koni yellows and whatever springs (swift, does hyperco make them for g35?) will get you there.