I've got myself wrapped around the axle trying to decide what to do about my anti-roll bar(s), mainly due to my inquisitive engineering brain, and reading this thread: Suspension threadI have a 2004/5 S2000, which I found to be too soft on track (and round roundabouts!). I upgraded to Meister R coilovers with 10kg spring rates all round. It works pretty well as a compromise, although it's a touch hard at the back end for the road and I end up with the damping wound up high on track to resist body roll.

I'm aiming at a (probably) unattainable panacea of supple on road and composed in roll on track. I know I'm probably thinking far too hard about it for my given skill level, but it's got the geek in me wound up and interested! So, the main influences so far on my decisions about what to do next are as follows:

• I want to increase ARB stiffness (new ARBs) to reduce roll and reduce the need to crank up the damping
• I don't want to increase the rear ARB stiffness much (if at all), due to multiple comments by a few people regarding rear wheel articulation, skipping, spinning etc.
• I don't want the upset the balance of the car. It seems to respond well to trail braking into corners (and it's very much required in slower corners), although I find power oversteer is pretty difficult to obtain unless I'm really trying hard, so I'd have thought it's erring on the side of understeer at the moment, although I don't mind a bit of stable 'push' in high speed stuff, for confidence's sake.

Using the information in the aforementioned thread, I created myself a spreadsheet, to characterise any potential changes against the various OEM setups (see here). I calculated the total rates at the wheel (coil plus ARB, taking motion ratio into account) for both front and rear, the stiffness relative to 04 OEM values, and the stiffness 'balance' front to rear (overall, and coil/ARB components). What is interesting is that the overall balance has steadily become stiffer towards the front (apart from 02/03), even for the CR, thus theoretically becoming more understeery (although I realise there may be other influences at work). So, is the CR seen as the pinnacle just because it's stiffer and more predictable (safe/understeery)?

So, what does this mean for my car? Well, with the Meisters on it, there has been a very small shift towards being relatively stiffer at the rear (see line 16 of the spreadsheet - mainly due to the effect of the motion ratios, I assume, because the relative stiffness of the coils on their own would lead you to think it would be the other way around), but not at a noticeable level at my skill level. With the combination of wanting to increase ARB stiffness, and not wanting to increase rear ARB stiffness, naturally this means an increased front ARB stiffness. This would make the balance move further to the front though, and promote understeer. On the one hand, I don't want this, but on the other hand, people seem to extol the virtues of the CR and I'd be closer to those values.

I've also read about roll centre adjusters, and roughly understand their effect, although mostly with respect to lowered cars (mine is only a tiny bit lowered, probably 10-15mm). So maybe I could use RCAs at the rear to raise the roll centre closer to the CG and balance the ARB at the front? Or I could soften the front coils to 9kg to reset the balance?

So, what do I do?!

Any thoughts welcome and appreciated (apart from "just drive it"! I've had to be in the house this evening, so I'm doing this research to avoid spending anything more on the car!).

Rgds
Chris

 

IMO a road and track S is always quite a big compromise.

But in general, let the ARBs control body roll, and let the dampers do the damping. I've actually reduced spring and damping rates a lot but gone stiffer on the bars over the last 2 years. As much as I'm giving away though

I'd also say you can spend hours on theory, but unfortunately as I've found, you have to try different things to suit your driving and the tracks you go on.

You'd have to be a very serious track day user to warrant making lots of changes though. Trackday are about having fun and mastering your car, not lap times.

 

Interesting thread.

What is your alignment settings though before worrying about spring rates / ARBs?

You might be able to fine due it via camber and toe.

Agree with MB though, it does look like you have gone a bit OTT on the spring rates. But I guess it depends what you drive on. Using ARBs is fine on the track but you lose the nature of independant suspension which is very useful on the road.


Mine is used on B roads and with std springs, Koni dampers and a nice WIM setup (2deg camber all around) it is very capable as it soaks up bumps very well. It's ok on the track too - a little bit of roll but again its always going to be a compromise with it being a daily drive.

 

Stiffer front anti roll bar transformed my 2006 S2000. It made a much bigger difference than the coilovers did to the handling of the car. I opted for the whiteline as its one of the stiffest bars you get before upgrading to one of the top of the line adjustable ARBS.

It weighs a ton thou which isn't ideal but i love it on track, i feel very little in the way of downsides on the road but on the track it pays dividends.

Yesterday after 7 weeks of waiting my Eibach adjustable rear anti bar arrived. I plan to put it on the softest setting so that i keep the front a fair bit stiffer than the rear. In hindsight i probably shouldn't of ordered it but i wanted to keep some balance. I will see how i get on with it and go from there.

In terms of what ive read on here all the racers in the US run very thick very strong front bars and little or no rear bar. The main reason being they are worried about the rear wheel lifting when cornering.

Front bar gets a big thumbs up from me!

 

Get some sticky tyres for it. I have Michelin Pilot Sport Cups. A good geo and some trackday time with tuition. You just need to get used to driving the car on absolute limit and feel comfortable in regaining control when it oversteers.

 

Agree with Tomy,,and as I hinted at before, you need to be pretty competent before you start fiddling too much. I'd say I worried to much about this early on rather than driving the car. There's a risk you can mod your way around big errors in your driving.

I make only a few clicks of changes, if any between different circuits now. Example being Rocky this weekend, I found understeer in, and oversteer out. Easy to blame this on setup? Or was it going in too fast?

 

From many years on here, be wary of threads from the US! I've not found any issues on lifting a rear wheel on UK circuits.

 

I must admit when i first read this i thought that there tracks must be pretty uneven to cause a wheel to lift due to ARB stiffness. Im hoping my Eibach makes a noticeable difference without overdoing it. The main reason i chose the eibach for the rear is that its not much stiffer than the 99-01 ARB when on its softest setting.

I assume you run both Rear and Front ARBS with no problems Mark? Do you mind if i ask what brand you use? Once ive fitted my rear one i wont be doing anything other than realignment and then keep the car as it is.

 

Blimey; fine for track, but a tad like a springboard for the road!

At the risk of wrecking it, I'd go for the higher-rate ARBs and back off the springs a bit plus CR ARBs all round? That ought to make it road-compliant, but you might introduce a bit of rear-wheel hop in the bumpy corners. But I'd have thought it would be skittish with 10s at the rear now.

The trouble is, the only way to find what works for you is to change one set of variables at a time. That's what the engineers end up doing in the final testing stage.

A s/h 00-01 front ARB would be a cheap and easy change; a CR rear might be more expensive. New springs more so...

 

You get a nice compromise between an 01 and a CR like that with 8Kg front and 9Kg rear and a 362 RARB; the allegedly best-handling versions.

You'll probably find it's shit but theoretically...