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Another thread has my CRs spring rates (according to SCC Magazine) at:
CR 392 lb/in (7.00 kg/mm) 342 lb/in (6.22 kg/mm)
I also know that a lot of S2k owners go with KW Variant 3's which are:
Front Spring Rate (lbs/inch): 515
Rear Spring Rate (lbs/inch): 515
Basically what's the impetus for setting spring rates?
In the case of the CR, Honda has gotten driver feedback over the course of a decade to make adjustments.
But how do they decide on rates? Why not 507 front / 442 rear?
And is there any math/science involved when an aftermarket company decides on 515/515?
Are these rates arbitrary, or are there other considerations involved, ie: vehicle weight, weight distribution, or do they make assumptions that people who are in the aftermarket for coilovers will be doing a certain type of driving?
Right now I'm on the fence about what direction to go with my car. I love auto-x (and the idea of prepping it for STR is very appealing once the rules are finalized). But I had a track day recently, and they got their hooks in me now, as well.
So I'm just trying to gather info at this point and would like to know a little bit of the concepts, and thought process that goes into decision making (like spring rates), so when i do start making choices, they'll be based on something more substantial other than some guy saying, 'Go with the KWs, I have them and they're awesome.'
I read through your post several times, and I have yet to understand the problem. What's preventing you from tracking your car with the current suspension? Why do you want to swap? What do you hope to gain?
If you want to learn about suspension theory, there are a number of options. Even old books are generally still valid, since the concepts haven't changed.
I'm partial to Race Car Engineering by Van Valkenburgh, but Carroll Smith's books are entertaining and there is always Milliken and Milliken if you want the theory.
Originally Posted by mikegarrison,Jun 9 2009, 12:33 PM
I read through your post several times, and I have yet to understand the problem. What's preventing you from tracking your car with the current suspension? Why do you want to swap? What do you hope to gain?
If you want to learn about suspension theory, there are a number of options. Even old books are generally still valid, since the concepts haven't changed.
I'm partial to Race Car Engineering by Vanvalkenburg, but Carroll Smith's books are entertaining and there is always Miliken and Miliken if you want the theory.
Oh, that's simple, I hope to gain knowledge. I'll never live in Ancient Rome, but that doesn't mean I don't want to know the history. So, I may decide to never actually go with an aftermarket coilover, but that's not going to stop me from wanting to understand the motivations for how/why people set their cars up the way they do.
The automotive aftermarket is driven by car enthusiasts who love to tinker with their rides. I'm just curious to know the motivation for person 'x' to go out and spend $2k on coilovers. Is it because they want to put the sticker on their car? is it because they think purlpe and yellow is a cool color combo? Or is there a distinct performance advantage going with a 515/515 spring stiffness?
Unfortunately my copy of 'Tune To Win' has been loaned out, and probably will never return. But if the Milliken books are good for theory, I'll give them a look.
Originally Posted by Boyracer40,Jun 9 2009, 01:48 PM
Or is there a distinct performance advantage going with a 515/515 spring stiffness?
In general, there is a performance advantage to going stiffer and stiffer on the track. But it makes the car less and less streetable and also less and less forgiving of drivers who are not smooth.
KW in particular has a very expensive 7-post rig to help them tune/determine their valving and spring rates for the platform.
Most good aftermarket suspension companies, and OEM manfuacturers all look at everything from unsprung weight, tire sizing, motion ratios and corresponding wheel rates, etc... to determine what to do. The smaller aftermarket companies put general shock/damping curves and a 'best guess' for spring rates for various applications.
Stiffer springs reduce body roll/travel - reducing bumpsteer, especially when cars that are lowered. Their are tons of explanations to your question so like Mikegarrison said, it's hard to answer such a general question.
And there are 2 versions of KW V3s, one with 456/456 spring rates and another with 515/515.
[QUOTE=Billj747,Jun 9 2009, 01:52 PM]KW in particular has a very expensive 7-post rig to help them tune/determine their valving and spring rates for the platform.
Most good aftermarket suspension companies, and OEM manfuacturers all look at everything from unsprung weight, tire sizing, motion ratios and corresponding wheel rates, etc... to determine what to do.
Originally Posted by Boyracer40,Jun 9 2009, 02:16 PM
so shall i assume Honda would choose a softer set up, when compared to the KWs for marketablilty reasons (a car that's track worthy, but not so stiff that it compromises ride comfort to the extent that it would dissuade the daily driver from buying it?)
And conversely, the KW's are set up with the competitive driver in mind?
Also, the adjustable perch on the KW's is for lowering/raising ride height, correct?But does a more compressed spring translate to a stiffer ride?
Of course Honda has to balance ride quality and performance for any of their products. KW tends to have softer springs compared to their competitors for a ride quality and grip standpoint and use the dampers to control the body roll rather than the spring (which is better in many ways).
No offense, but it sounds like there is room for knowledge improvement about suspension systems.
Aftermarket coilovers have a threaded shaft and corresponding spring perch that the spring sits on. You can raise or lower the spring perch to raise or lower the ride height. Raising the ride height too far for that spring length with start to compress the spring, also known as "pre-load". Pre-load can affect the ride quality slightly.
As you lower the spring perch, you are putting less tension on the spring (or in KW's case, the softer helper spring), this does not affect ride quality from a spring stand point but can reduce the compression travel (making bottoming out the suspension more prone depending on the suspension) and adding more droop travel. KW's are a double-adjustable damper with separate compression from rebound damping. You can adjust the ride quality and handling in 2 ways (compression & rebound) which can fine-tune/tailor the handling or ride quality of the car.
Read up on some of said books, and talk to more people at the track.
Spring stiffness
