Looking for any experience to guide me on this mod. I posted this in a different thread but it attracted none so I thought I

 

[QUOTE]Originally posted by cdelena
[B]..........
After a day at the track, and two opinions from more experienced drivers, I am pretty much convinced that improved coilovers are something I want to do.

 

No doubt the S2K suspension is quite good from the factory. I'm actually pretty happy with the spring rates, although a lower ride height is almost always helpful.

Where I feel improvement is really needed (and I think the auto-x guys will agree) is in the shocks. In high speed corners (80-100 mph) the back end feels a little mushy. At the Streets of Willow (Rosamond, CA) going into turn one there are some undulations in the road and the back end does not feel particularly good. It isn't that the car is loose, but the back end doesn't feel planted and I'm convinced it's shock tuning - probably rebound IMO.

cdelena, spend some time talking with the auto-x guys when they get back from Florida. Road course issues are different than auto-x (usually you'll want to be a little softer and understeer more because of the higher speeds and bumpier conditions), but they'll give you a good start.

Based upon the stock handling characteristics and what the auto-x guys have found to date, if you add springs, you definitely want the fronts to add proportionally more stiffness than the rear. How much more is up to you, but all it should do is increase understeer and decrease oversteer. I wouldn't want to add too much, preferring instead to fine tune with front swaybar and adjustable shock damping. Check the King Motorsports page for stock spring rates and their upgraded spring rates.

UL

 

ultimate lurker, your comments are very much in line with my observations and the conversations with the more experienced drivers that have tried my car One of them, an instructor that has driven the same track for many years in many cars, did a number of laps and commented,

 

ultimate lurker is right on the understeering tuning.
You don't want to have to worry about going oversteer at 100mph in racing.
S2000 rear and feels light and don't give you confidence in high speed corner. I always have a feeling that the rear end going tocome around on me and goto a spin but once you come over that feeling. you can go fast and the rear would never come around.
Lowing your car may not have that much effect.
It lower the C.G. but reduce the suspension travel that
is needed on a rough track.

 

I agree with ultimate lurker. The car definitely needs more rebound damping at the track. If you're going to spend money on new coilovers, spend more and look at the best, maybe the Penske's or JRZ's. You'll want something that's 3 way adjustable - rebound, low speed compression and high speed compression. I'm sure the Penske's are rebuildable, I don't know about the others.

There are some shock threads, some with Jason's comments.
Like me, you're getting sucked into making the car a racecar. Unfortunately, that middle ground of a street/race car is not nirvana - it won't be as fast as it could be at the track, and may be uncomfortable on the street.

P>S> I think the stock shocks are KYB's

 

I would really love to learn how to correctly "read" handling and correct for issues using shock damping & spring tension. I have Ohlin's on my BMW motorcycle (more or less the best available alongside Penske's) and screw around with the damping and preload adjustments, but really am not skilled at setup. And that's only two "corners" instead of four!

Without the proper tuning skills, or a talented cohort, I wonder if investment in highly adjustable coil-overs might cause more problems then they solve...

 

That's a good point pfb, on my other car I sometimes wonder if I wouldn't have been better off just buying a well sorted out, non-adjustable system - it's a lot of work.

But, you do learn a lot, and when you get a tuning change right, it's awesome because you made the car faster.

Personally, if I'm looking at developing a suspension for a street car that sees some lapping days, but no competition, I wouldn't bother with the super expensive JRZ or Penske shocks. Extra adjustments are extra variables, and you should be measuring tire temps, segment times and have an experieneced driver to tune those.

Rather, a rebound adjustable only set of coilovers, perhaps custom valved might be better for the average person. It would keep the costs under $2000 for the whole car too.

UL

 

First off, I agree that I have found the back end a little unsettled on rough tracks at high speed. However, if you're running race tires, I might look to those as a possible source of some of the problem. When I ran 225/50 s-02's in the front and 245/45 AVS-Sports in the rear (yes, I know it's a bad idea to mix brands), I found this amplified the problem severely. Of course this was largely due to the different compounds front and rear, but I think the size combination also makes the car twitchy. Anyway, just something to consider.

Be careful what other people will tell you is and is not streetable. Everyone has a different definition. I usually find my definition of streetable is too harsh for at least 90% of the people I encounter, so I'm probably more likely to err in the way of too harsh for the street. I have one friend who drives his RX-7 with no interior, bald A-032R's and no windshield wipers (to save weight) on the street. Someday I should post the story about the time I borrowed his car and encountered an unexpected total downpour of rain... but anyway, he's about the only person I know of who has a looser definition of streetable than I do.

I think you will be unhappy with 10/6 kg rates because I think they're trying too hard to use messed up spring rates to save the world. The car just isn't that far out of balance that you need to throw so much bias into your spring rates to make it handle right. Besides, I don't consider 10 kg/mm streetable for this car, so even the 10/8 combo is too stiff, in my opinion.

My HKS springs are 5.1 kg/mm front and 6.5 kg/mm rear. They lower the front 27mm and rear 29mm. Like I said before, there isn't much that I wont call streetable, but really the car is not very streetable already with this setup. My girlfriend is quickly losing her patience with me having to go into EVERY driveway totally sideways, still scraping, and often having to just park somewhere else because I just can't clear the dip. And that's only 1.1 inches lower than stock. As for stiffness... when I feel like driving hard, I wouldn't mind them being a little bit stiffer, but when I'm tired and just trying to get home, they are already too stiff. On bumpy roads or bad freeways I damn near get a concussion and I'm constantly worrying about bending a rim. So this is probably a good setup for street/track since it's livable on the street, but not by too much margin. I would say even for the most die-hard street warrior, anything over 7.5 maybe 8 kg/mm on either end is really not streetable anymore. I don't really consider my ride height streetable anymore, and I'm only down 1.1 inches, so certainly more would be out of the question for the street.

I understand your concerns to build a good street/track car, but if this is your daily driver (unfortunately, it is mine), or if you even drive it a lot on the street, don't get sucked into turning it into a trailor bitch because you went too far with your mods listening to advice from people who don't have to drive your car to work every day.

As for this "you'll want something that's 3 way adjustable"... most of the racers I know will tell you that the more adjustments you have available to you, the harder it is to get the thing to handle right. Keep it simple. You don't have an R&D team to sit down and work out the physics to set it up properly for every situation. 2-way adjustable will be more than enough to keep you busy turning dials all the time in search of that perfect balance. Like pfb said, highly adjustable coil-overs are just going to cause more problems than they solve at your level.

 

Hi Guys:
You guys are true enthusiasts. I read with interest about all of your comments.
I have the following in my car, ( Basically I follow whatever Ron Bauer and Annie Gill, national caliber auto-x drivers, put into their car, at least the ones that I know of):>))
JRZ shocks, Comptech prototype front sway bar, which is at least 25% stiffer than the Mugen one, Kumho V700 auto-x tires, 245/225, camber -1.5/-2.5.
I have autoxed the S2000 for 12 months now, and I slowly but surely improved the drivability of the car, with the Mugen bar and the JRZ shocks, it was almost there...., but just not quite. Then I got one of the five front bars that Mike at Comptech produced. The result is such that I could finally put the power down, and the car stayed secure, wheras before I could'nt put it down as early, and the tail would be loose.
In a nutshell, Cdelena, I think you would be pleasantly surprised with just a change to a stiffer front bar.
I found the JRZ shocks helped some, but not too noticable, the Mugen bar was noticably better than the stock one, but the Comptech bar was WOW.
Sorry for the long post.
Cheers,

Eric Cheung
'00 Silver/Black #2616