imstimpy

I'm Jon. Sorry I didn't get a good chance to talk. We are actually really friendly

sirbunz

While the SSM car is down for repairs, Dave and I brought our AP1s out. I feel we made another break through in the rear stability of the car.

2003 S2000 (I,H,E, no tune)
-900/700 Springs (a bit high Rear for street tires)
-13.5" F/R Ride Height (measurement fender to hub center, much higher than most)
-Ohlins TTX Shocks (simply pimp ... low compression F/R, medium rebound R, low rebound F)
-OEM "CR" Front Bar/Adjustable End-Links (Much softer than most ... I HATE pushy cars)
-Small Gendron Rear Bar (full Soft ... NEW "preferred" setting is disconnected)
-OEM Torsen Diff (not convinced of gains from the OSG if suspension is tuned right)
-245/40/17 Dunlop Z2s (older, take offs from early 2013, decided not to use)
-255/40/17 Rivals (purchased new summer 2013, <75 runs). We ran 34f/32r on my gauge, 36f/34r on Dave's gauge.
-Front ... "0" Toe, -3.5 Camber, 6' caster (higher camber than most, use offset bushings on UCA))
-Rear ... 1/16 Toe-In L/R, 1/8 Total Toe-In, -3' Camber (less toe, higher camber than most)

I haven't driven mine at an event in a while, but assumed the setting/alignments were the same as last time and hopefully hasn't changed in 5k mile of street driving. The courses were at the big concrete Pad in Wilmington and the courses were large, 60 second courses with a few fast pace, but mostly low-mid speed switchbacks, sweepers, digs, etc ... so pretty much a variety of elements. Wilmington is very similar to concrete in Toledo (high grip/fresh), but has more bumps to deal with. Temps were cold (approx 45-50 high). I brought my daily driven 245 Z2s on 17x9 wheels and ran the test & Tune with them. Dave brought his car and the 255/40/17 Rivals on 17x9 949s.

Saturday was the TnT, Sunday was a Divisional event. After Dave drove my car, he liked the Turn-In much better than his car, so we decided to co-drive my AP1. Sundays course was about 1/3 slow digs and straights (AP1 nightmare), 1/3 tight inset switchbacks/lane changes (S2000s love these), a high speed sweeper followed by a mid sweeper that integrated 2 outside entry Chicago boxes (tire killers), and a sweeping finish with a pinch cone. We decided on the 255 Rivals despite the cold conditions because they were newer and the Z2s seemed to no longer heat up due to age. Needless to say, rear stability was really going to be tested on this course.

Dave liked the car, I did not ... but it is much better than my late, fully built STR CR I won the Pro Finale and 2nd at Solo Nationals with in 2012. As many of you know, I really push the corner exits and try to hold as much momentum as possible. The rear was fine unless you got on the throttle early. Initial corner entry was stable, but corner exit was not. Shock changes did not help in the slightest for my 2nd run. On my 3rd run, I disconnected the rear bar entirely (something I always said not to do). I was amazed after my 3rd run. The car, without any other changes went from high oversteer power out corner exit to mild oversteer, early power out corner exit with just this change. Looking at the wear on the tires, less rear camber could be used. The fronts were rolling over to the indicators even with the high camber. My final run was a really strong run compared to the National talents at the event and my normal STR finishes. I feel this setup is ideal for the S2000 and the easiest STR car I have driven to date outside of the MX5 and capable of some amazing times! Feel free to use these settings or ask questions. My goal is to continue to make this car faster and simplify the STR settings (aka chaos) for everyone!

-Marc

iamxpl

Thank you for this valuable information. I am currently on older used Rivals, my settings are close to what you have.
-3.0 front, 6.5 caster and 0 toe. -2.5 camber and 1/16th total toe.
Spring rates are 800f/650r
Koni DA custom valving
Gendron 1.25 hollow on 5th setting.
Disconnected rear bar.
255/40 rivals

I am new to the class but compared to my previous set up with the HKS hipermax 3 and rear bar, the new set up is way more accepting with the earlier input on the gas. I dont have my current video from yesterdays test and tune but i have the last event up on my thread. see my sig link.

sillyboybmxer

Is at least a 100lb spring bias F to R the general rule here? I'm ordering some new springs this week and want to make sure I get it right. Thinking 700/600 for a "dual purpose" car but I could care less about street comfort, I'm here to

ConeKiller2

You guys are likely getting better rear grip with no bar due to the heavier rear springs and smaller f/r bias difference. If you went lighter I'm rear spring and used a small bar you would still have adequate mid corner stability and better slalom transision. The no rear bar will be more stable but compromise response in transitions. Marc I believe smallest gendron rear is still more than miata bar. Also cr front is less than smallest front gendron. Again using higher springs with less bar. It comes down to preference. Either lower springs with more bar or less springs more bar.

Sent from my SAMSUNG-SM-N900A using Tapatalk

sirbunz

I agree ... Certainly everyone has a preference and to each their own. This is hardly a stab in the dark though...

Looking back, I have tried 8 different spring combos in STR so far, anywhere from 400 to 800 in the rear and 500 to 1000 up front! I have tried tons of alignment settings, the no rear bar, Miata rear bar, 2 different Gendron rear bars, practically every front Bar Honda makes, an Ankeny double blade bar, every Gendron minus the solid, Comptech, Whiteline, Saner, etc up front. I liked the smallest Gendron up front, and the small Gendron in the rear (there is a smaller/thinner available, just have to ask Bill). I have driven many more setups and cars outside my own. This is the first combo that is working for me. Taking a wild guess, I have probably driven 50+ different STR cars since this began. Outside of a well known NC Miata that is no longer driven, this is my favorite so far. The fact that this has works on most the popular tires, even the Z2s which usually like less camber says something. I think its more about ride height than anything. Also, the bar, seems to be doing lots of other things with the typical STR setups than we can predict on paper. Eliminating it as a factor has proven successful so far, particularly in the rear.

Bottom line, my driving style needs the ability to put down power while the suspension is loaded and allow me to quickly catch it on exit without pushing or sliding too far the opposite direction afterwards unless I induce it. This setup was a first, now a second in proving successful, given the limited traction conditions and older tires. You don't have to take my word for it, many others have driven my cars as well, been a passenger with me, had me as a passenger/instructor, etc! Also, this car is a pain in the rear driving on public roads. This alignment makes the car wonder all over unlevel roads at speed.

-Marc

sirbunz

If I were to continue, I would try 900/600-650 again with my current setup. The last I tried that, I was much lower, had the OSG, and a rear bar. So the 100 different rule is more like 2/3rds to 3/4ths of the front for me! Probably personal preference here. I also love the new Swift springs. You dont have many options in 2.25" width equivalents, but the 2.5x8" has lots of options. They are also lighter for you weight mod guys! Patrick @ URGE got me hooked on them.

My info is here for those wanting to try something new. Many of you have it figured out and im not implying those settings are wrong. As I did with my Stock class CR after I won Nationals with it, I have no problem sharing my setting when I feel they work and make driving the car easier.

-Marc

hinduboy74

Car: 2004 S2000 AP2

Ride height: Still trying to find best height with current setup
Springs: 650f/650r
Front Bar: Stock Bar (Waiting for Moddicitions bar which has same 3 way settings as Saner)
Rear Bar: Currently Disconnected
Alignment: Researching as well
Tires: 255 square Z2s
Wheels: TR Motorsports 17x9
Bushings: OEM
Differential: OE torsen

A little background on my setup, I ended up going with the Eibach Multi-Pro R2 Double Adjustable coil overs with 650 square springs. I know most people go quite stiff up front but I got an amazing deal that I couldn't pass up on a new set and I wanted a more streetable setup as well. How will the car react and can I compensate with the lack of stiff front springs with a stiff bar setting or more compression/rebound? I know an option is to get stiffer springs and swap the fronts but I want to know if I can get away with not doing that.

I have an appointment with the go to shop to get the car aligned and corner balanced next week so still have time to decide on ride height and specs.

Let me know your thoughts.

imstimpy

To continue with what Marc said, a rough rule of thumb is 2-2.5Hz natural frequencies, then .2-.4Hz separation between front and rear. On track, theoretically the rear should be higher to give it a head start in reacting to the bump but autocross tends to run the stiffer NF on the opposite of the drive wheels. I know of at least one national championship car that runs a higher NF on the rear with RWD. There are ways to calculate the NF but it serves only as a starting point for testing. By that math, anywhere between 500 and 900 is a mathematically "correct" spring rate for the S2000.

For example, 900F/700R puts the NF at roughly 2.71 and 2.37Hz. Decreasing to 700F/550R puts the NF at roughly 2.39 and 2.10Hz. The seat of the pants difference should be more compliance with a lower NF and that is what I'm testing this weekend.

Ideally, springs are chosen to match the car's chassis, then bars are added to decrease roll and offer an easy way to tune balance. A topic of much debate here has been what, exactly, is the correct spring rate for the chassis, the tires, the driver, the alignment, the surface (and a million other variables). As you can see, there is a lot that goes into a spring selection and what one person likes, or tests to go fast, might be another's slowest setup.

I haven't seen many people properly compensate the removal of the rear bar but there have been a few people running near square springs and no rear bar. If my car is balanced with 700F/550R, some stiff front bar and some soft bar, I can achieve similar roll bias (read: balance) by disconnecting the rear bar and adding around 150lbs to the rear spring rates. The primary difference between the two setups would be relative stiffness of the springs over the rear (suspension compliance, squat, and shock loading) and the amount of connection the inside and outside rear tires have under cornering load. I've been curious about how the car drives since Nick Jackson did it a few years ago, and since Marc is trying it as well.

Here is a link to my spreadsheet. It is read-only, but it hopefully has some useful information within.
https://docs.google.com/spreadsheets...it?usp=sharing

I personally use Hyperco springs for two reasons: 1) they produce consistent, quality springs (Swift does, as well) and 2) I can get them cheaply so I can test.

hinduboy74

Anyone have any insight on the question I posed in the previous post?