Hey all, I'm needing some input on direction to go with front sway bars. I know this is a question that has been done to death and I've read some old threads however none that really had input specifically on my concerns.

So right now I've got an '00 AP1 in half baked STR trim. I'm running 255 nonstagger with Ohlins w/ 10/8K springs, stock sway bars. Alignment is camber -3.2*F/-3.0*R, 0 front toe and .10* total rear toe in. No aero, stock weight. Currently on RS4s however they're on the way out so I'm planning for RT660s. I've been autocrossing the car and have gotten to a point where it feels fairly neutral. Initially the car felt slightly pushy after installing the ohlins however I think I've gotten that ironed out after messing around with alignment, rebound settings, and tire pressures. At my last outing I'm finding that my car is too lazy in slalom and corner transitions and it's killing my confidence. I'd like to get that squared out with a new front sway bar however I am unsure about which one to get.

I am interested int he Karcepts bar with the .188 core however I am concerned that it will induce too much understeer or that it will be too stiff for any future track based driving I want to do. Based on the STR setup threads it seems like people run even more front stiffness than I'm planning and I've also read that the calculations for the bar's stiffness is approximate and may actually be less; so that's reassuring however I'd still like some additional input from those who have run similar setups. I am also informed that they're .120 core is out of stock at the moment so they're softest bar is not a current option. They other bar I'd consider is the SBG bar however it seems like it might be too soft as it is a 32 mm hollow bar. The Moddiction/saner bar seems to have completely disappeared?

So really my question boils down to two parts:
1) For those with similar setups how did the karcepts bar work out?
2) Is anyone using the Karcepts bar at the track, and if so what is your setup?

Thanks in advance.

 

Honda S2000

I used the 1.25" x .25" hollow bar on my S2000 at about 416 lbs also run the CR rear sway. Both front bars would be a great upgrade for the car.

 

The Gendrons were very nice. Even more spendy than the Karcepts. I have a moddiction that I later changed to the Karcepts front bar. I run the .250 wall Karcepts on the 2nd setting (1 from full soft) and it works well with my setup. when the tires get a bit heat cycled out or worn out it will get more pushy as there is not enough front grip then to work as well with the stiffer bar. But otherwise feels about perfect. And even though it seems hard to believe with 1" of drop on an s2k, you absolutely can adjust the Karcepts with one hand at ride height just like he says in his documentation. It is a super nice bar.

As note, I am running 750F/600R spring rates with -3.5 degrees of front camber and -2.8 in the rear and 7.8 degrees of caster. 0 toe front and rear

 

I run 700F/650R with the gendron 1.25 bar and karcepts rear bar. -3.4 front - 2.9 rear, with about 12.75" hub to fender ride height front 12.5 rear. 245 a052's on 9's.
Karcepts bar is about set half way to full stiff and gendron bar at about 416lbs too.
Car is pretty neutral to me.
the real key to balance for me is the rear bar, i set the front bar to where i like it, then fine tune the rear with the karcepts bar. the karcepts bar rear is really good and easy to adjust on the fly for differing surfaces/conditions

 

On the gendron rates I notice they’re softer than the karcepts but also that they mark a softer rate for the oem bar as well. Presume that this is because the rate is derived from a different calculation, particularly since they note that this is for wheel rates.

Do any of you think tire will play a big roll. I was on RS4s which already wasn’t the most grippy however they definitely were on their way out so maybe that contributed to the cars push I was. I recall once my buddy had a legacy gt and it was pushy as hell however it became a lot more neutral after switching from mpss to re71r.

 

From my experience with autox, a worn out/old tire makes an STR s2000 push on entry, wander mid corner, then oversteer on exit when riding the limit.
I wouldnt tune a car based on old tires. As my tires get old typically i have to take out a half step of front bar.

 

You know, this pretty much describes my experience last weekend to a T. I kind of first attributed this to being rusty, over driving the car, and having new parts in the car. The last time I autocrossed the car 3 yrs ago it was all stock except 255 square RE71R. Then I got busy with my job and then the pandemic hit. Since then I put in ohlins, lowered the car, re did alignment, brakes, etc.... But when I autocrossed the car last weekend I was surprised since the car would plow on entry more than I expected and then over steer on exit if I whipped it around too fast. I kind of associated this behavior combo with overdriving cars from autocrossing a NA Miata previously but I was kind of surprised at how much it plowed since with the RE71R I only had oversteer and I hadn't even put a big front bar in yet. I managed to tame this by adjusting tire pressures and rebound settings and being more conservative on corner entry. Felt pretty neutral by the end of the weekend and it would turn in like I expected it to. The one thing that stayed consistent between now and 3 yrs ago was that the car felt lazy in the slaloms. In between slaloms it would feel like it took a moment for the front to settle before the next cone which made it feel less stable and on the sweeper entering the slalom at high speed the steering input felt vague and it was kind of hard to place the car exactly where I wanted for the slalom entry. That's why I chose front sway bars as my next step. Looking back and reviewing the weekend it came to mind that maybe my tires were really on the way out. I was still 5 seconds behind the usual PAX leader in a STU evo, which is my usual differential from 3 yrs ago, and it was kind of disappointing after all these mods but also some what reassuring since I was on much slower tires (I think he was on Yokos). I know tires alone won't make up that differential so I know I need driver mod and to tidy up the suspension.

 

I'll echo the sentiment that on lower grip surfaces, I typically like less front bar and/or more rear. I'm on karcepts bars both ends and highly value the adjustability. I am comfortable adjusting either bar mid-heat with a single driver and would do bigger events with a dual driver. I think you could also adjust between track/autocross duty well but can't speak to the absolute rates you'd want for track. Generally speaking, front bar has more influence on corner entry, rear bar on exit. I mention that mainly to point out that your exit oversteer would likely be best addressed by less rear bar. Also depends on the driver though. If you understeered in and then the front caught and caused exit on oversteer, I'd have to know the driver inputs before guessing at setup. Front swaybar should help make the front end quicker to respond to inputs and stabilize the car a bit in slaloms. If you're turning the wheel too quickly, you're going to overload the outside front tire and cause it to understeer. Front bar will also make the car more pushy in sweepers. It's a give and take but again, driver is a significant factor.

I used to think my car was too pushy under most recommended setups but have been working more on being efficient under braking. That typically means trail braking into things with a smooth release and transferring to throttle smoothly again. It seemed most the fastest guys liked setups that I considered pushy and I realized that was likely the difference. I was not good at braking zones and typically over-used maintenance throttle as too much of a crutch. Just saying that setup is dependent on driver style. I try to be flexible in my style until I'm nearer the top.

 

Tire is everything. I hate to say it, but all the work you did to make your car feel neutral will be useless once you throw on new tires.
Get the tires you're going to compete with, then see how you feel about the responsiveness of your front end. Then make changes IMO.

It sounds like you already know what you gotta do and get those RT660's.

As for your questions, I used the Saner Bar & NC Miata bar combo. I loved this bar set up, but Im a hotboi and I wanted more so I went with Karcepts bars. Now I run 1370lbs 6/6 up front and 129lbs 1/7 in the rear. I use the settings from autocross at the track because that's predictable to me but I could always increase the rear swaybar easily. Not cheap but awesome.
I also noticed you didnt list your ride heights. Those matter too. The reason why many STR guys use a positive front rake is so more weight sits on the rear wheels to prevent wheel lift. The S2000 rear has such little travel already.

 

Question to the OP. What is the reasoning for going to the 660's? I think cost and wear are better so that may be it. If wanting to be more competitive I think you will be a lot happier with the A052s. They do suck for $$ and wear reasons though, but less so with plenty of camber. I run RS4s for track nights and throw on the A052s for a fast session at those and for autox events.