S2000 Stock class autocross information
06-14-2016, 02:53 AM
#133
08-25-2016, 02:50 PM
#134
Probably won't know till next year once tire rack tests them or a couple people try them out. Everyone's running RE71Rs.
09-06-2016, 08:02 AM
#135
Hello All,
Can’t say I’m crazy experienced having only 2 years Autocrossing the s2000 being locally competitve and 3 years in the hobby, but a lot has changed since this FAQ was last updated and thought it would be good to update for people who are interested in getting into the Hobby and making it easier for them to get started. I also hate to see this thread stagnant as I find myself in one of the most fun and competitive classes in the sport.
I’ve found myself in a class of 10-15 cars locally on occasion with 8 dedicated competitors in my class who come out including several s2000s.
I did not write this originally but I would like to see PedalFaster’s work not go to waste so let’s get started!
Feel free to comment on your experiences and I’ll go back and add them in!
I will need to go back manually using the web editor to add many of the hyperlinks so bare with me.
S2000 STREET CLASS AUTOCROSS SETUP FAQ, v3.00
Last updated: August 30, 2016
-----
TABLE OF CONTENTS
1. INTRODUCTION AND SCCA CLASSIFICATIONS
2. STREET-LEGAL MODIFICATIONS
2.1 Essential setup items
2.1.1 TIRES
2.1.1.1 Tire sizes
2.1.1.2 Bridgestone RE71R
2.1.1.3 BF Goodrich Rival S
2.1.1.5 Other tires
2.1.2 SWAY BAR
2.1.2.1 Small Fortune Racing / Gendron
2.1.2.2 Saner Performance Fabrication
2.1.2.3 Ankeny Racing Enterprises
2.1.2.4 Comptech
2.1.2.5 Karcepts
2.1.3 ALIGNMENT
2.2 Nice-to-have setup items
2.2.1 BRAKE PADS
2.2.2 SHOCKS
2.2.3 WHEELS
2.2.4 EXHAUST
2.3 Personal preference setup items
2.3.1 HARNESS
2.3.2 ENGINE MODIFICATIONS
3. WHAT'S THE BEST YEAR S2000 TO BUY FOR AUTOCROSS?
4. RECOMMENDED READING
-----
1. INTRODUCTION AND SCCA CLASSIFICATIONS
Having seen a bunch of threads like this one go by on the Racing and Competition forum, I figured it was high time that someone wrote an autocross setup FAQ to get the commonly-asked stuff out of the way. Since I was bored, I wrote it myself.
This document is a mix of personal experience autocrossing S2000s at the national level for two years, ongoing correspondence with people still running S2000s nationally, and information gleaned from various posts on this board.
This FAQ covers setup for the current SCCA Solo 2 Street class autocrossing. The S2000 is eligible for the following classes in SCCA national-level competition:
• A Street (CR only) (AS)
• B Street (AP1 and AP2) (BS)
• B Street Prepared (BSP)
• F Prepared (FP)
• D Modified (AP1 motor) (DM)
• E Modified (AP2 motor) (EM)
• Street Modified (SM)
• Street Touring Roadster (STR)
This FAQ does not cover setup for SCCA autocross classes other than Street, nor does it cover setup for track days or performance street driving, although some information here may be useful for those applications.
Differences in setup between the AP1 ('00 - '03), AP2 ('04 - '08), and CR models are noted where applicable.
Stock Class died out in 2014 and was replaced officially in 2015 with Street Class.
-----
2. STREET-LEGAL MODIFICATIONS
I'm going to somewhat arbitrarily divide the allowed changes into three categories -- the essentials, the nice-to-haves, and the personal preference items.
The essentials -- tires, a sway bar, and an alignment -- are the still the things you must have to be competitive. If you're on a tight budget or not concerned about the last couple of tenths, you can end your list of changes here without feeling like you're leaving a ton of time on the table; both Tours and Pros have been won in cars with just these essential changes made. If you've ever heard of the 80/20 rule (the first 20% of the cost nets 80% of the benefit, and the last 20% of the benefit is responsible for 80% of the cost), the essentials constitute that first 80% of benefit.
The nice-to-haves -- brake pads, shocks, wheels, and exhaust -- are the remaining 20%. These changes are each worth at most a few tenths on a sixty second course. That being the case, while there is benefit to making these changes, they're not necessities; the cost-to-benefit ratio for this category is rather worse than that of the essentials.
Last and least as well are the personal preference items -- harness and engine modifications. A harness may not pay off directly with faster times, but some people prefer them, and those people may go faster because of it. Engine modifications could provide small time improvements, but the cost-to-benefit tradeoff just doesn't make sense.
2.1 Essential setup items
2.1.1 TIRES
Since this was last updated R-compounds have been banned from Street Class. R-compounds are allowed in Street Prepared Classes and up, but those classes are not this FAQ’s purpose. The most significant change that you can make to any street car destined for autocross use is switching to Extreme performance summer tires. Extreme performance Summer tires use softer, stickier rubber for the tread but keep stiffer sidewalls of street tires driven properly, can net huge (multiple seconds on a sixty second course) time improvements over the OEM Summers. They give up wear rate to put down good times. I had a set only last me 7000 road miles plus about 100 autocross runs and used purely for autocross you get maybe 150-200 runs.
This is still a lot better than the 50-60 runs of the R-compounds, and that was one of the reasons why the R-compounds have been banned from Street class. SCCA decided it wants this hobby to be accessible to more people and not have to make people spend as much money to be competitive and have fun.
2.1.1.1 Tire sizes
There are two approaches to tire sizing on the S2000 -- staggered and equally-sized (or "square").
For AP1s a typical staggered setup is now 205 front/ 225 rear. Thanks to wider wheels the AP2s run 225 or 245 front/ 245 or 255 rear.
The current preferred setup is to run an extremely stiff front sway bar to reduce wheelspin, which in turn requires running equally-sized tires front and rear to maintain handling balance. The preferred square tire sizes are 225 all-around for AP1 cars, and 245 all-around for AP2s and 255 square for CRs. Note that non-CR AP2s may experience tire rubbing on the front fender liners if 255s are used.
2.1.1.2 Bridgestone RE71R
The vast majority of top national-level Street-class autocrossers use RE71R tires. The RE71R's advantage over its primary competitor, the Rival S right now, is its stiffer sidewall that makes it more responsive in the slaloms from what I’ve seen and run lower tire pressures which can also give slightly better compliance. The AP1 tire sizes aren’t as easy to get anymore and they don’t make a 245 wide in 16” size for the AP1s so they are limited to the 225 size.
Optimal for an AP2 RE71R tire pressures are in the Low to Mid 30s for the front and Upper 20s in the rear.
The cost of these tires will range from $150-$180 depending on the size.
2.1.1.3 BFG Rival S
The BF Goodrich Rival S is an alternative to the RE71R. Consensus is that the RE71R is a slightly faster tire for most applications, but the BFG is slighty cheaper and better for street use but is almost as fast. They use slightly softer sidewalls and that makes them easier to drive at the limit althought the S2000 is so sensitive I don’t know it matters much. I have never driven them, but have seen reviews for them done by Blacktop Racing using the ND miata which they reported were good but not quite with the RE71Rs.
Optimal Rival S tire pressures are in the Mid 30s for the front and Low 30s in the rear.
2.1.1.5 Other tires
There are many other Extreme Summer tires available in sizes suitable for the S2000, including the Dunlop Direzza ZII Star Spec, the Hankook RS3 V2, Nitto NT555 and the Toyo R1R.
All of these tires tend to work well in the rain with the exception of the Hankooks which like a lot of heat. Some of the other tires also will have longer tread life as the top two tires have managed to give up tread life for grip without failing the government tests for 200 tread wear. I expect for the 2017 season a lot of these other companies will come up with new tires of their own to fight back. In years past there have been 3 or more competitive tires while currently the RE71R is top dog.
If you have other tire selections or would like to include to add your experiences regarding some of these tires.
2.1.2 SWAY BAR
A sway bar is important on the S2000 for two reasons. The first is that, with R-compound rubber and even with Extreme Summer rubber, the S2000 rolls enough in corners to lift its inside rear wheel off of the ground or nearly off the ground. The S2000's limited-slip differential is a Torsen unit; one characteristic of the Torsen is that when one wheel has no traction, it acts as an open differential. What this translates to in an autocross is wheelspin, and lots of it. A bigger front sway bar reduces body roll and plants the rear end, allowing you to power out of corners instead of spinning the inside rear wheel helplessly.
The second reason for a big front bar is that the S2000, particularly the AP1, is more prone to oversteer than pretty much any other recent mass-produced car. This makes the stock car a lot of fun on the street, but throw in rapid transitional maneuvers and the added grip of Extreme performance tires, and the results get a little too exciting when driven at the edge. The tire setups usually used in autocross narrow the width differential between the front and rear contact patches, exacerbating this tendency towards oversteer. A big front sway bar tames the rear end, making driving the car less of a white knuckle experience, especially in slaloms.
The demands of autocross and the fact that spring changes are not allowed in Street dictate the use a stiffer front sway bar than is optimal for performance street or even track use. There are a number of front sway bars (e.g. Mugen, Muz, etc.) available for the S2000, but bars not specifically designed for autocrossing aren't stiff enough for Solo competition. You typically want at least twice the stock stiffness for optimum performance.
The five sway bars that are designed with autocross in mind are built by Small Fortune Racing (aka "Gendron"), Saner Performance Fabrication, Ankeny Racing Enterprises, Comptech, and Karcepts. Each has its own pros and cons:
2.1.2.1 Small Fortune Racing / Gendron
The Gendron bar is a NASCAR-style adjustable sway bar which is adjusted by varying the point where the endlink attaches to the bar arm. It has a fairly broad adjustment range via six endlink mounting holes spanning a few inches of the arm. Because it's a modular bar (the arms bolt to a tubular center section), its stiffness can also be changed by substituting a different center section -- Gendron sells hollow 1.375" center sections as well as solid and hollow 1.25" center sections. The 1.375" bar is generally necessary to control wheelspin on non-CR cars; the 1.25" bars are sufficient for CRs.
The drawback of the Gendron bar is that the bar ends are rather thick, which, like the Saner, can lead to interference between the endlinks and the shock bodies. This can be addressed by machining some material off of the arms to make them narrower and/or using lower profile endlinks (the ones linked here also require drilling out the adjustment holes to accommodate their larger stud diameter).
The Gendron bar is available only through Small Fortune Racing, a small shop run by autocrosser Bill Gendron. The bar costs around $900.
2.1.2.2 Saner Performance Fabrication
The Saner bar is a conventional 1.25" solid three-way adjustable sway bar. Its great benefit is that, at $275, it's significantly less expensive than the other options. The Saner bar's range of adjustment is narrower than either the Comptech's or the Gendron's, though; its stiffest setting isn't stiff enough for maximum performance on non-CR cars.
The Saner bar has its share of problems as well. There are spacers between the bar and the endlinks to ensure sufficient endlink articulation, but these deform quickly. The Saner is also prone to making harmless but annoying clicks and clunks. Because of the use of endlink spacers, it has clearance issues with aftermarket shocks with larger-than-stock bodies -- the endlinks may scrape against the shocks, but this can usually be alleviated by careful alignment of the bar. Lastly, but perhaps most importantly, availability of the Saner bar is extremely variable, subject to the whims of its manufacturer; several people have endured months-long waits for their bars. Plan your order timing accordingly.
The Saner Performance website is http://www.sanerperformance.com. Saner's phone number is (772) 324-1339.
2.1.2.3 Ankeny Racing Enterprises
Ankeny Racing Enterprises ("ARE") has begun producing 1.5" blade-adjustable sway bars for the S2000. These haven't seen widespread use at the national level yet, but their specifications suggest that they should be a good, easily-adjusted alternative to the Gendron and Saner bars.
The ARE bar costs around $900 with one adjustable blade, with a second adjustable blades costing an additional $125.
The Ankeny Racing Enterprises website is ankenyracingenterprises.com. ARE's phone number is (805) 527-1137.
2.1.2.4 Comptech
Comptech used to produce an autocross-specific sway bar for the S2000. Comptech went bankrupt in 2007 and was reconstituted as a race and engine-only shop; it no longer builds S2000 sway bars. Comptech bars still appear for sale occasionally, though.
The Comptech has an unusual design. I started writing a description of the mechanics of its operation, but a few paragraphs later, decided that they're beyond the scope of this FAQ. Suffice it to say that, unlike a conventional sway bar, the Comptech is adjusted by moving a bolt between a series of holes in the bar's center section, thus varying its stiffness (click here for an image of the bar and holes). The process for making adjustments on the Comptech bar is rather more involved than that for a conventional bar. The Comptech's real drawback, though, is its price -- just under $1000. What you get for your money is a broad range of adjustment and a beautiful set of anodized aluminum mounting brackets.
Be aware that there have been two generations of the Comptech bar. The first generation bar had an unfortunate tendency to snap in two (for the visually-minded, there's a picture here). The second generation bar shares the same basic design, but was redesigned to be more durable. To my knowledge there have been no reports of failures of the second generation bar, although it should also be noted that relatively few people have used it. The bottom line is buyer beware when buying a used Comptech bar, although since the first generation bar has not been produced in years, the risk of finding one on the used market is slim.
2.1.2.5 Karcepts
The Karcepts bar is relatively new only being available the past few years. This bar works similarly to the Gendron bar, but has been optimized further for the s2000 application. It has 6 positions on the endlinks and has 5 different center sections you can install, but it is easier to adjust and was designed to be adjustable between runs. Stiffnesses vary from twice the stock stiffness to over six times stock stiffness depending on which of the 5 center sections sizes and position you choose. People commonly choose the 0.25” thick wall and use the first (minimum stiffness) position for B street use. This fixes the stock twitchiness but without causing unwanted amounts
If you have stock shocks you will need to swap shocks side to side to get clearance to make that possible, but it won’t prevent you from using any of the settings you just will need to jack up the car to get clearance to move the endlink. You will also need to zip tie brake lines out of the way.
This bar is also cheaper than some of the other higher end stiffer bars at $675 shipped from the Karcepts website. Stiffnesses vary from twice the stock stiffness to over four times stock stiffness. People commonly choose the 0.25” thick wall.
From DavidNJ: "The Karcepts is a very clever design. It has a quick broad range of adjustment. The spined torsion bars are available in a broad range of stiffnesses. I'm on the 0.188" wall thickness hollow bar one hole from the stiffest setting. It is also available with 0.120" wall thickness, .250" wall thickness, solid, and solid stepped up to 1.375" in the center (the spines are all 1.25
. The range is 25% stiffer than the CR bar on the softest setting of the softest bar, to 500% on the stiffest setting of the stiffest bar. My setting is about 265% stiffer.
The arms are gorgeous machined aluminum. While the kit is $675, additional torsion bars in different sizes are $150 each. A rear bar is also available if moving to a modified class."
2.1.3 ALIGNMENT
A proper alignment is important for autocrossing, and compared to the other changes you'll be making, a bargain at less than $100-$150. Individual alignments vary, but the general consensus falls in the following ranges:
• Front toe - 0" to 1/8" total toe out
• Front camber - maximum available (generally between -1.5 to -1.8 degrees)
• Rear toe – For AP1s is 1/16" to 1/4" total toe in and For AP2s the norm is now 0” to 1/16” total toe in
• Rear camber - -0.2 to -0.5 degrees more than the front camber
Drivers with stock shocks or front sway bar may want to consider more conservative settings (e.g. more rear toe-in or less front camber).
2.2 Nice-to-have setup items
2.2.1 BRAKE PADS
The S2000's stock brake pads have difficulty getting the most out of R-compound tires, especially on concrete surfaces. For this reason, most people run grabbier, more fade-resistant brake pads. See this thread and this thread for discussion of brands and models which have been used successfully.
R compounds though are no longer legal for street class so the stock pads are a good budget pad since they are $60 a pair for each end of the car instead of the $150+ per end many of the aftermarket pads cost. I like the progressiveness of the engagement of the stock pads, but many like the grabbier feel of the aftermarket pads. Many of the aftermarket pads do last longer though. I replace my stock front pads every year or every 300 runs or so plus 20k miles of street driving. The stock AP2 pads dust nearly as much as some of the aftermarket pads anyway so you are not saving yourself any cleaning effort there.
Note that you should avoiding using full-race brake pads like Hawk Blues on an autocross car. Race pads need a few laps to come up to working temperature before they stop well; you'll never have that opportunity at an autocross.
From DavidNJ " The Hawk Street/Racer pads are the street version of the DTC30 and work from low temperatures. Very controllable with a high coefficient of friction for a street pad, they can easily handle anything an RE71r can deliver. Both my feedback and from nationally competitive drivers who have driven my car."
2.2.2 SHOCKS
There's only one off-the-shelf performance shock available for the S2000 -- the Koni Sport (also known as the Koni Yellow). There's some debate over whether the Konis are an improvement over the stock shocks. The Konis have stiffer rebound damping but softer compression damping than the stock shocks; some feel this makes the car easier to drive at the limit, while others believe it slows the car's reflexes, but the differences are fairly subtle either way. One indisputable benefit of the Konis is that they're adjustable at all four corners, which gives you some options for fixing handling problems. Unlike some other Koni fitments, the rears can be adjusted with the car on the ground. Konis run a bit over $600 for a set.
Non-CR S2000s benefit significantly from shocks with autocross-specific valving, which make the car much more controllable at the limit. Koni Yellows can now be revalved to autocross-specific specs by Koni North America; see this thread for more information.
Before Koni began offering autocross-specific valving, many national-level competitors used custom high-end shocks (Moton, Penske, JRZ, etc.). These are still an option for people willing to pay out the nose (expect to pay $2000 - $5000 for a set) for shocks that can be custom-valved to the driver's specifications, and which may perform incrementally better as a result. When shopping for high-end shocks, be sure to work with a vendor with S2000-specific autocross knowledge.
From DavidNJ:"The stock shocks are mono-tube designs. The Koni's are twin-tube with valving, according to Angelo Zarra of ANZE Engineering, dates from 1946. Given the stock ride height and springs of the Street classes, do they really have an advantage?
Penske 7500 Double Adjustables should be under $3400 and should work at stock ride heights. I believe ANZE, Penske, Kaz Technologies, and Ankeny all can valve them for autocross. Ankeny has also valved relatively inexpensive Bilstein PSS shocks for autocross. I believe Bilstein will also revalve them."
2.2.3 WHEELS
The only Stock-legal, (somewhat) off-the-shelf lightweight wheel options for the AP1 cars are the six-spoke forged BBS wheels that were available as a factory option in Japan. Four of these shave off about nineteen pounds of rotating weight. Unfortunately, the JDM (Japanese domestic market) six-spoke wheels are hard to come by in North America -- used wheels occasionally appear on s2ki.com's For Sale and Wanted forum or on eBay, and quickly sell in the $1000-$1500 range. Some stores specializing in JDM products may be able to get them, but expect to pay $2000+ and wait several months for the privilege.
The Tire Rack generally carries at least one lightweight wheel model appropriate for the AP2, but the specific manufacturer and model varies, so check their website for details. The current popular wheel for the AP2s is the OZ Alleggeritas which are $1300 shipped from Tirerack plus the cost of tires.
The S2000's wheels have very large offsets, and in addition, the front brake clearance is very tight; as a consequence, most custom race wheel manufacturers (e.g. Fikse, Complete Custom Wheel) have difficulty fabricating Stock-legal front wheels.
The '00-'03 stock sizes are 16" x 6.5" +55 mm front, 16" x 7.5" +65 mm rear. The '04-'08 stock sizes are 17" x 7" +55 mm front, 17" x 8.5" +65 mm rear.
2.2.4 EXHAUST
The S2000's stock exhaust is very efficient, so power gains from aftermarket exhausts are at best incremental -- the only justification for getting an aftermarket exhaust for an autocross car is weight savings. The stock exhaust weighs over fifty pounds; relatively inexpensive single exhausts like those from Spoon, Speed, or JIC save over thirty pounds off of the back of the car, and extremely lightweight titanium exhausts like the Amuse single can shave over forty pounds. Autocrossers on a budget can also fabricate their own lightweight single exhaust by sawing off the stock mufflers and welding in a lightweight universal race canister. Either way, bring earplugs -- lightweight single exhausts are deafeningly loud without silencers, and using a silencer noticeably reduces high-end power.
2.3 Personal preference setup items
2.3.1 HARNESS
Some people prefer to be fastened tightly to their seat when autocrossing. If you're one of these people, you may want to consider a harness, but be aware that SCCA rules prohibit the use of full harnesses in convertibles not equipped with roll bars. As such, if you want a harness, make sure you get a roll bar as well, or alternately, get just a lap harness belt.
The CG-Lock is an inexpensive and easy-to-install alternative to a lap harness, but can wear seatbelts prematurely.
2.3.2 ENGINE MODIFICATIONS
SCCA Street class rules permit very minimal internal engine modifications -- effectively just rebuilding the engine to stock specs, except for the use of the manufacturer's first standard overbore, not to exceed 0.020". Given the tiny potential gains and large cost of rebuilding the engine (Grassroots Motorsports on their Project Celica: "Our $3500 rebuild has netted us 4 horsepower"), not to mention the extreme length of this FAQ, it's not really worth discussing here.
No one has measured power gains from aftermarket air filters exceeding a dyno's range of error, so only install one if you feel like making a change for change's sake.
-----
3. WHAT'S THE BEST YEAR S2000 TO BUY FOR AUTOCROSS?
If you are considering buyig an S2000 specifically for Autocross, at this point it’s clear the AP2s are more competive on a national level today because of the lack of tire width available to the AP1s. 245s are not available with the right sidewall aspect ratio limiting the AP1s to 225s. For the FRSs tire size discrepancies are not an issue as I know people who ran 215s in a field of people running 225s , but because of the AP2’s wider rear wheels it can take advantage of wider tires all around. AP1s are still locally competitive. Amongst AP2s there is little difference in competiveness because they all have the same larger wheel sizes. Although there are significant differences in suspension, wheel and tire size, powerband, and gearing between the various years and variants of the S2000, examples of each generation and variant have been campaigned with success at the national level. Buy the car that suits your budget and personal preferences as all S2000s make fun autocross cars requiring little modification to go out and be competitive.
-----
4. RECOMMENDED READING
SCCA 2016 National Solo Rules - The SCCA Solo rulebook is available online at http://cdn.growassets.net/user_files...pdf?1471970253
A-arm bracket thread - The brackets attaching the front upper A-arms to the chassis on AP1 cars tend to crack and pull away from the frame under heavy use. See this thread for more information. The brackets were strengthened in the AP2 update, and there have been no reports of them failing on AP2s.
s2k2fast4me's 2002 Year in Review - s2k2fast4me won Nationals in a Boxster in 2001, then bought an S2000, built it up over the course of the 2002 season, then drove it to a second national championship at the end of the year. His detailed account of his car development process is informative for anyone considering doing the same.
-----
VERSION HISTORY
v1.0 - FAQ created - 04.01.01
v1.01 - Added Recommended Reading section, table of contents, and section numbering; performed general cleanup but probably introduced several jet-lag induced errors as well - 04.01.15
v1.1 - Added '04+-specific commentary where appropriate, revised Tires section to reflect the 2004 season's tire choices, added the "What's the best year?" section, and made numerous minor content and formatting revisions - 04.09.06
v1.2 - Incorporated lessons learned during the 2004 season and feedback received from other members; added information on the 2005 R-compound tire choices - 05.02.05
v1.3 - Updates to reflect new tire options, AP2 setup, and new setup trends from the 2005 and 2006 seasons - 07.02.11
v1.31 - Added note about 245/45R17 Kumho V710 rubbing on the front fenderwell - 07.09.03
v1.32 - Fixed broken link to Jason Saini's alignment - 08.08.19
v1.33 - Changed title from "S2000 autocross setup FAQ" to "S2000 Stock class autocross setup FAQ" and added link to 2009 rulebook - 09.03.14
v1.34 - Updated the URL for the Saner website - 09.03.16
v2.0 - First major update in two and a half years; updated every section to reflect the current state of the art - 09.09.13
v2.01 - Corrected the prices of the Gendron and ARE sway bars and noted that one national championship has been won on a square tire setup - 09.09.16
v2.02 - Fixed some characters that weren't rendering correctly that were introduced in the v2.0 update - 09.12.06
v2.03 - Updated SCCA Solo rule book link to point to the 2010 rule book and removed the white space from the version history section - 10.08.17
V3.0 – FAQ updated for Street Class – 08.30.16
Can’t say I’m crazy experienced having only 2 years Autocrossing the s2000 being locally competitve and 3 years in the hobby, but a lot has changed since this FAQ was last updated and thought it would be good to update for people who are interested in getting into the Hobby and making it easier for them to get started. I also hate to see this thread stagnant as I find myself in one of the most fun and competitive classes in the sport.
I’ve found myself in a class of 10-15 cars locally on occasion with 8 dedicated competitors in my class who come out including several s2000s.
I did not write this originally but I would like to see PedalFaster’s work not go to waste so let’s get started!
Feel free to comment on your experiences and I’ll go back and add them in!
I will need to go back manually using the web editor to add many of the hyperlinks so bare with me.
S2000 STREET CLASS AUTOCROSS SETUP FAQ, v3.00
Last updated: August 30, 2016
-----
TABLE OF CONTENTS
1. INTRODUCTION AND SCCA CLASSIFICATIONS
2. STREET-LEGAL MODIFICATIONS
2.1 Essential setup items
2.1.1 TIRES
2.1.1.1 Tire sizes
2.1.1.2 Bridgestone RE71R
2.1.1.3 BF Goodrich Rival S
2.1.1.5 Other tires
2.1.2 SWAY BAR
2.1.2.1 Small Fortune Racing / Gendron
2.1.2.2 Saner Performance Fabrication
2.1.2.3 Ankeny Racing Enterprises
2.1.2.4 Comptech
2.1.2.5 Karcepts
2.1.3 ALIGNMENT
2.2 Nice-to-have setup items
2.2.1 BRAKE PADS
2.2.2 SHOCKS
2.2.3 WHEELS
2.2.4 EXHAUST
2.3 Personal preference setup items
2.3.1 HARNESS
2.3.2 ENGINE MODIFICATIONS
3. WHAT'S THE BEST YEAR S2000 TO BUY FOR AUTOCROSS?
4. RECOMMENDED READING
-----
1. INTRODUCTION AND SCCA CLASSIFICATIONS
Having seen a bunch of threads like this one go by on the Racing and Competition forum, I figured it was high time that someone wrote an autocross setup FAQ to get the commonly-asked stuff out of the way. Since I was bored, I wrote it myself.
This document is a mix of personal experience autocrossing S2000s at the national level for two years, ongoing correspondence with people still running S2000s nationally, and information gleaned from various posts on this board.
This FAQ covers setup for the current SCCA Solo 2 Street class autocrossing. The S2000 is eligible for the following classes in SCCA national-level competition:
• A Street (CR only) (AS)
• B Street (AP1 and AP2) (BS)
• B Street Prepared (BSP)
• F Prepared (FP)
• D Modified (AP1 motor) (DM)
• E Modified (AP2 motor) (EM)
• Street Modified (SM)
• Street Touring Roadster (STR)
This FAQ does not cover setup for SCCA autocross classes other than Street, nor does it cover setup for track days or performance street driving, although some information here may be useful for those applications.
Differences in setup between the AP1 ('00 - '03), AP2 ('04 - '08), and CR models are noted where applicable.
Stock Class died out in 2014 and was replaced officially in 2015 with Street Class.
-----
2. STREET-LEGAL MODIFICATIONS
I'm going to somewhat arbitrarily divide the allowed changes into three categories -- the essentials, the nice-to-haves, and the personal preference items.
The essentials -- tires, a sway bar, and an alignment -- are the still the things you must have to be competitive. If you're on a tight budget or not concerned about the last couple of tenths, you can end your list of changes here without feeling like you're leaving a ton of time on the table; both Tours and Pros have been won in cars with just these essential changes made. If you've ever heard of the 80/20 rule (the first 20% of the cost nets 80% of the benefit, and the last 20% of the benefit is responsible for 80% of the cost), the essentials constitute that first 80% of benefit.
The nice-to-haves -- brake pads, shocks, wheels, and exhaust -- are the remaining 20%. These changes are each worth at most a few tenths on a sixty second course. That being the case, while there is benefit to making these changes, they're not necessities; the cost-to-benefit ratio for this category is rather worse than that of the essentials.
Last and least as well are the personal preference items -- harness and engine modifications. A harness may not pay off directly with faster times, but some people prefer them, and those people may go faster because of it. Engine modifications could provide small time improvements, but the cost-to-benefit tradeoff just doesn't make sense.
2.1 Essential setup items
2.1.1 TIRES
Since this was last updated R-compounds have been banned from Street Class. R-compounds are allowed in Street Prepared Classes and up, but those classes are not this FAQ’s purpose. The most significant change that you can make to any street car destined for autocross use is switching to Extreme performance summer tires. Extreme performance Summer tires use softer, stickier rubber for the tread but keep stiffer sidewalls of street tires driven properly, can net huge (multiple seconds on a sixty second course) time improvements over the OEM Summers. They give up wear rate to put down good times. I had a set only last me 7000 road miles plus about 100 autocross runs and used purely for autocross you get maybe 150-200 runs.
This is still a lot better than the 50-60 runs of the R-compounds, and that was one of the reasons why the R-compounds have been banned from Street class. SCCA decided it wants this hobby to be accessible to more people and not have to make people spend as much money to be competitive and have fun.
2.1.1.1 Tire sizes
There are two approaches to tire sizing on the S2000 -- staggered and equally-sized (or "square").
For AP1s a typical staggered setup is now 205 front/ 225 rear. Thanks to wider wheels the AP2s run 225 or 245 front/ 245 or 255 rear.
The current preferred setup is to run an extremely stiff front sway bar to reduce wheelspin, which in turn requires running equally-sized tires front and rear to maintain handling balance. The preferred square tire sizes are 225 all-around for AP1 cars, and 245 all-around for AP2s and 255 square for CRs. Note that non-CR AP2s may experience tire rubbing on the front fender liners if 255s are used.
2.1.1.2 Bridgestone RE71R
The vast majority of top national-level Street-class autocrossers use RE71R tires. The RE71R's advantage over its primary competitor, the Rival S right now, is its stiffer sidewall that makes it more responsive in the slaloms from what I’ve seen and run lower tire pressures which can also give slightly better compliance. The AP1 tire sizes aren’t as easy to get anymore and they don’t make a 245 wide in 16” size for the AP1s so they are limited to the 225 size.
Optimal for an AP2 RE71R tire pressures are in the Low to Mid 30s for the front and Upper 20s in the rear.
The cost of these tires will range from $150-$180 depending on the size.
2.1.1.3 BFG Rival S
The BF Goodrich Rival S is an alternative to the RE71R. Consensus is that the RE71R is a slightly faster tire for most applications, but the BFG is slighty cheaper and better for street use but is almost as fast. They use slightly softer sidewalls and that makes them easier to drive at the limit althought the S2000 is so sensitive I don’t know it matters much. I have never driven them, but have seen reviews for them done by Blacktop Racing using the ND miata which they reported were good but not quite with the RE71Rs.
Optimal Rival S tire pressures are in the Mid 30s for the front and Low 30s in the rear.
2.1.1.5 Other tires
There are many other Extreme Summer tires available in sizes suitable for the S2000, including the Dunlop Direzza ZII Star Spec, the Hankook RS3 V2, Nitto NT555 and the Toyo R1R.
All of these tires tend to work well in the rain with the exception of the Hankooks which like a lot of heat. Some of the other tires also will have longer tread life as the top two tires have managed to give up tread life for grip without failing the government tests for 200 tread wear. I expect for the 2017 season a lot of these other companies will come up with new tires of their own to fight back. In years past there have been 3 or more competitive tires while currently the RE71R is top dog.
If you have other tire selections or would like to include to add your experiences regarding some of these tires.
2.1.2 SWAY BAR
A sway bar is important on the S2000 for two reasons. The first is that, with R-compound rubber and even with Extreme Summer rubber, the S2000 rolls enough in corners to lift its inside rear wheel off of the ground or nearly off the ground. The S2000's limited-slip differential is a Torsen unit; one characteristic of the Torsen is that when one wheel has no traction, it acts as an open differential. What this translates to in an autocross is wheelspin, and lots of it. A bigger front sway bar reduces body roll and plants the rear end, allowing you to power out of corners instead of spinning the inside rear wheel helplessly.
The second reason for a big front bar is that the S2000, particularly the AP1, is more prone to oversteer than pretty much any other recent mass-produced car. This makes the stock car a lot of fun on the street, but throw in rapid transitional maneuvers and the added grip of Extreme performance tires, and the results get a little too exciting when driven at the edge. The tire setups usually used in autocross narrow the width differential between the front and rear contact patches, exacerbating this tendency towards oversteer. A big front sway bar tames the rear end, making driving the car less of a white knuckle experience, especially in slaloms.
The demands of autocross and the fact that spring changes are not allowed in Street dictate the use a stiffer front sway bar than is optimal for performance street or even track use. There are a number of front sway bars (e.g. Mugen, Muz, etc.) available for the S2000, but bars not specifically designed for autocrossing aren't stiff enough for Solo competition. You typically want at least twice the stock stiffness for optimum performance.
The five sway bars that are designed with autocross in mind are built by Small Fortune Racing (aka "Gendron"), Saner Performance Fabrication, Ankeny Racing Enterprises, Comptech, and Karcepts. Each has its own pros and cons:
2.1.2.1 Small Fortune Racing / Gendron
The Gendron bar is a NASCAR-style adjustable sway bar which is adjusted by varying the point where the endlink attaches to the bar arm. It has a fairly broad adjustment range via six endlink mounting holes spanning a few inches of the arm. Because it's a modular bar (the arms bolt to a tubular center section), its stiffness can also be changed by substituting a different center section -- Gendron sells hollow 1.375" center sections as well as solid and hollow 1.25" center sections. The 1.375" bar is generally necessary to control wheelspin on non-CR cars; the 1.25" bars are sufficient for CRs.
The drawback of the Gendron bar is that the bar ends are rather thick, which, like the Saner, can lead to interference between the endlinks and the shock bodies. This can be addressed by machining some material off of the arms to make them narrower and/or using lower profile endlinks (the ones linked here also require drilling out the adjustment holes to accommodate their larger stud diameter).
The Gendron bar is available only through Small Fortune Racing, a small shop run by autocrosser Bill Gendron. The bar costs around $900.
2.1.2.2 Saner Performance Fabrication
The Saner bar is a conventional 1.25" solid three-way adjustable sway bar. Its great benefit is that, at $275, it's significantly less expensive than the other options. The Saner bar's range of adjustment is narrower than either the Comptech's or the Gendron's, though; its stiffest setting isn't stiff enough for maximum performance on non-CR cars.
The Saner bar has its share of problems as well. There are spacers between the bar and the endlinks to ensure sufficient endlink articulation, but these deform quickly. The Saner is also prone to making harmless but annoying clicks and clunks. Because of the use of endlink spacers, it has clearance issues with aftermarket shocks with larger-than-stock bodies -- the endlinks may scrape against the shocks, but this can usually be alleviated by careful alignment of the bar. Lastly, but perhaps most importantly, availability of the Saner bar is extremely variable, subject to the whims of its manufacturer; several people have endured months-long waits for their bars. Plan your order timing accordingly.
The Saner Performance website is http://www.sanerperformance.com. Saner's phone number is (772) 324-1339.
2.1.2.3 Ankeny Racing Enterprises
Ankeny Racing Enterprises ("ARE") has begun producing 1.5" blade-adjustable sway bars for the S2000. These haven't seen widespread use at the national level yet, but their specifications suggest that they should be a good, easily-adjusted alternative to the Gendron and Saner bars.
The ARE bar costs around $900 with one adjustable blade, with a second adjustable blades costing an additional $125.
The Ankeny Racing Enterprises website is ankenyracingenterprises.com. ARE's phone number is (805) 527-1137.
2.1.2.4 Comptech
Comptech used to produce an autocross-specific sway bar for the S2000. Comptech went bankrupt in 2007 and was reconstituted as a race and engine-only shop; it no longer builds S2000 sway bars. Comptech bars still appear for sale occasionally, though.
The Comptech has an unusual design. I started writing a description of the mechanics of its operation, but a few paragraphs later, decided that they're beyond the scope of this FAQ. Suffice it to say that, unlike a conventional sway bar, the Comptech is adjusted by moving a bolt between a series of holes in the bar's center section, thus varying its stiffness (click here for an image of the bar and holes). The process for making adjustments on the Comptech bar is rather more involved than that for a conventional bar. The Comptech's real drawback, though, is its price -- just under $1000. What you get for your money is a broad range of adjustment and a beautiful set of anodized aluminum mounting brackets.
Be aware that there have been two generations of the Comptech bar. The first generation bar had an unfortunate tendency to snap in two (for the visually-minded, there's a picture here). The second generation bar shares the same basic design, but was redesigned to be more durable. To my knowledge there have been no reports of failures of the second generation bar, although it should also be noted that relatively few people have used it. The bottom line is buyer beware when buying a used Comptech bar, although since the first generation bar has not been produced in years, the risk of finding one on the used market is slim.
2.1.2.5 Karcepts
The Karcepts bar is relatively new only being available the past few years. This bar works similarly to the Gendron bar, but has been optimized further for the s2000 application. It has 6 positions on the endlinks and has 5 different center sections you can install, but it is easier to adjust and was designed to be adjustable between runs. Stiffnesses vary from twice the stock stiffness to over six times stock stiffness depending on which of the 5 center sections sizes and position you choose. People commonly choose the 0.25” thick wall and use the first (minimum stiffness) position for B street use. This fixes the stock twitchiness but without causing unwanted amounts
If you have stock shocks you will need to swap shocks side to side to get clearance to make that possible, but it won’t prevent you from using any of the settings you just will need to jack up the car to get clearance to move the endlink. You will also need to zip tie brake lines out of the way.
This bar is also cheaper than some of the other higher end stiffer bars at $675 shipped from the Karcepts website. Stiffnesses vary from twice the stock stiffness to over four times stock stiffness. People commonly choose the 0.25” thick wall.
From DavidNJ: "The Karcepts is a very clever design. It has a quick broad range of adjustment. The spined torsion bars are available in a broad range of stiffnesses. I'm on the 0.188" wall thickness hollow bar one hole from the stiffest setting. It is also available with 0.120" wall thickness, .250" wall thickness, solid, and solid stepped up to 1.375" in the center (the spines are all 1.25
. The range is 25% stiffer than the CR bar on the softest setting of the softest bar, to 500% on the stiffest setting of the stiffest bar. My setting is about 265% stiffer.The arms are gorgeous machined aluminum. While the kit is $675, additional torsion bars in different sizes are $150 each. A rear bar is also available if moving to a modified class."
2.1.3 ALIGNMENT
A proper alignment is important for autocrossing, and compared to the other changes you'll be making, a bargain at less than $100-$150. Individual alignments vary, but the general consensus falls in the following ranges:
• Front toe - 0" to 1/8" total toe out
• Front camber - maximum available (generally between -1.5 to -1.8 degrees)
• Rear toe – For AP1s is 1/16" to 1/4" total toe in and For AP2s the norm is now 0” to 1/16” total toe in
• Rear camber - -0.2 to -0.5 degrees more than the front camber
Drivers with stock shocks or front sway bar may want to consider more conservative settings (e.g. more rear toe-in or less front camber).
2.2 Nice-to-have setup items
2.2.1 BRAKE PADS
The S2000's stock brake pads have difficulty getting the most out of R-compound tires, especially on concrete surfaces. For this reason, most people run grabbier, more fade-resistant brake pads. See this thread and this thread for discussion of brands and models which have been used successfully.
R compounds though are no longer legal for street class so the stock pads are a good budget pad since they are $60 a pair for each end of the car instead of the $150+ per end many of the aftermarket pads cost. I like the progressiveness of the engagement of the stock pads, but many like the grabbier feel of the aftermarket pads. Many of the aftermarket pads do last longer though. I replace my stock front pads every year or every 300 runs or so plus 20k miles of street driving. The stock AP2 pads dust nearly as much as some of the aftermarket pads anyway so you are not saving yourself any cleaning effort there.
Note that you should avoiding using full-race brake pads like Hawk Blues on an autocross car. Race pads need a few laps to come up to working temperature before they stop well; you'll never have that opportunity at an autocross.
From DavidNJ " The Hawk Street/Racer pads are the street version of the DTC30 and work from low temperatures. Very controllable with a high coefficient of friction for a street pad, they can easily handle anything an RE71r can deliver. Both my feedback and from nationally competitive drivers who have driven my car."
2.2.2 SHOCKS
There's only one off-the-shelf performance shock available for the S2000 -- the Koni Sport (also known as the Koni Yellow). There's some debate over whether the Konis are an improvement over the stock shocks. The Konis have stiffer rebound damping but softer compression damping than the stock shocks; some feel this makes the car easier to drive at the limit, while others believe it slows the car's reflexes, but the differences are fairly subtle either way. One indisputable benefit of the Konis is that they're adjustable at all four corners, which gives you some options for fixing handling problems. Unlike some other Koni fitments, the rears can be adjusted with the car on the ground. Konis run a bit over $600 for a set.
Non-CR S2000s benefit significantly from shocks with autocross-specific valving, which make the car much more controllable at the limit. Koni Yellows can now be revalved to autocross-specific specs by Koni North America; see this thread for more information.
Before Koni began offering autocross-specific valving, many national-level competitors used custom high-end shocks (Moton, Penske, JRZ, etc.). These are still an option for people willing to pay out the nose (expect to pay $2000 - $5000 for a set) for shocks that can be custom-valved to the driver's specifications, and which may perform incrementally better as a result. When shopping for high-end shocks, be sure to work with a vendor with S2000-specific autocross knowledge.
From DavidNJ:"The stock shocks are mono-tube designs. The Koni's are twin-tube with valving, according to Angelo Zarra of ANZE Engineering, dates from 1946. Given the stock ride height and springs of the Street classes, do they really have an advantage?
Penske 7500 Double Adjustables should be under $3400 and should work at stock ride heights. I believe ANZE, Penske, Kaz Technologies, and Ankeny all can valve them for autocross. Ankeny has also valved relatively inexpensive Bilstein PSS shocks for autocross. I believe Bilstein will also revalve them."
2.2.3 WHEELS
The only Stock-legal, (somewhat) off-the-shelf lightweight wheel options for the AP1 cars are the six-spoke forged BBS wheels that were available as a factory option in Japan. Four of these shave off about nineteen pounds of rotating weight. Unfortunately, the JDM (Japanese domestic market) six-spoke wheels are hard to come by in North America -- used wheels occasionally appear on s2ki.com's For Sale and Wanted forum or on eBay, and quickly sell in the $1000-$1500 range. Some stores specializing in JDM products may be able to get them, but expect to pay $2000+ and wait several months for the privilege.
The Tire Rack generally carries at least one lightweight wheel model appropriate for the AP2, but the specific manufacturer and model varies, so check their website for details. The current popular wheel for the AP2s is the OZ Alleggeritas which are $1300 shipped from Tirerack plus the cost of tires.
The S2000's wheels have very large offsets, and in addition, the front brake clearance is very tight; as a consequence, most custom race wheel manufacturers (e.g. Fikse, Complete Custom Wheel) have difficulty fabricating Stock-legal front wheels.
The '00-'03 stock sizes are 16" x 6.5" +55 mm front, 16" x 7.5" +65 mm rear. The '04-'08 stock sizes are 17" x 7" +55 mm front, 17" x 8.5" +65 mm rear.
2.2.4 EXHAUST
The S2000's stock exhaust is very efficient, so power gains from aftermarket exhausts are at best incremental -- the only justification for getting an aftermarket exhaust for an autocross car is weight savings. The stock exhaust weighs over fifty pounds; relatively inexpensive single exhausts like those from Spoon, Speed, or JIC save over thirty pounds off of the back of the car, and extremely lightweight titanium exhausts like the Amuse single can shave over forty pounds. Autocrossers on a budget can also fabricate their own lightweight single exhaust by sawing off the stock mufflers and welding in a lightweight universal race canister. Either way, bring earplugs -- lightweight single exhausts are deafeningly loud without silencers, and using a silencer noticeably reduces high-end power.
2.3 Personal preference setup items
2.3.1 HARNESS
Some people prefer to be fastened tightly to their seat when autocrossing. If you're one of these people, you may want to consider a harness, but be aware that SCCA rules prohibit the use of full harnesses in convertibles not equipped with roll bars. As such, if you want a harness, make sure you get a roll bar as well, or alternately, get just a lap harness belt.
The CG-Lock is an inexpensive and easy-to-install alternative to a lap harness, but can wear seatbelts prematurely.
2.3.2 ENGINE MODIFICATIONS
SCCA Street class rules permit very minimal internal engine modifications -- effectively just rebuilding the engine to stock specs, except for the use of the manufacturer's first standard overbore, not to exceed 0.020". Given the tiny potential gains and large cost of rebuilding the engine (Grassroots Motorsports on their Project Celica: "Our $3500 rebuild has netted us 4 horsepower"), not to mention the extreme length of this FAQ, it's not really worth discussing here.
No one has measured power gains from aftermarket air filters exceeding a dyno's range of error, so only install one if you feel like making a change for change's sake.
-----
3. WHAT'S THE BEST YEAR S2000 TO BUY FOR AUTOCROSS?
If you are considering buyig an S2000 specifically for Autocross, at this point it’s clear the AP2s are more competive on a national level today because of the lack of tire width available to the AP1s. 245s are not available with the right sidewall aspect ratio limiting the AP1s to 225s. For the FRSs tire size discrepancies are not an issue as I know people who ran 215s in a field of people running 225s , but because of the AP2’s wider rear wheels it can take advantage of wider tires all around. AP1s are still locally competitive. Amongst AP2s there is little difference in competiveness because they all have the same larger wheel sizes. Although there are significant differences in suspension, wheel and tire size, powerband, and gearing between the various years and variants of the S2000, examples of each generation and variant have been campaigned with success at the national level. Buy the car that suits your budget and personal preferences as all S2000s make fun autocross cars requiring little modification to go out and be competitive.
-----
4. RECOMMENDED READING
SCCA 2016 National Solo Rules - The SCCA Solo rulebook is available online at http://cdn.growassets.net/user_files...pdf?1471970253
A-arm bracket thread - The brackets attaching the front upper A-arms to the chassis on AP1 cars tend to crack and pull away from the frame under heavy use. See this thread for more information. The brackets were strengthened in the AP2 update, and there have been no reports of them failing on AP2s.
s2k2fast4me's 2002 Year in Review - s2k2fast4me won Nationals in a Boxster in 2001, then bought an S2000, built it up over the course of the 2002 season, then drove it to a second national championship at the end of the year. His detailed account of his car development process is informative for anyone considering doing the same.
-----
VERSION HISTORY
v1.0 - FAQ created - 04.01.01
v1.01 - Added Recommended Reading section, table of contents, and section numbering; performed general cleanup but probably introduced several jet-lag induced errors as well - 04.01.15
v1.1 - Added '04+-specific commentary where appropriate, revised Tires section to reflect the 2004 season's tire choices, added the "What's the best year?" section, and made numerous minor content and formatting revisions - 04.09.06
v1.2 - Incorporated lessons learned during the 2004 season and feedback received from other members; added information on the 2005 R-compound tire choices - 05.02.05
v1.3 - Updates to reflect new tire options, AP2 setup, and new setup trends from the 2005 and 2006 seasons - 07.02.11
v1.31 - Added note about 245/45R17 Kumho V710 rubbing on the front fenderwell - 07.09.03
v1.32 - Fixed broken link to Jason Saini's alignment - 08.08.19
v1.33 - Changed title from "S2000 autocross setup FAQ" to "S2000 Stock class autocross setup FAQ" and added link to 2009 rulebook - 09.03.14
v1.34 - Updated the URL for the Saner website - 09.03.16
v2.0 - First major update in two and a half years; updated every section to reflect the current state of the art - 09.09.13
v2.01 - Corrected the prices of the Gendron and ARE sway bars and noted that one national championship has been won on a square tire setup - 09.09.16
v2.02 - Fixed some characters that weren't rendering correctly that were introduced in the v2.0 update - 09.12.06
v2.03 - Updated SCCA Solo rule book link to point to the 2010 rule book and removed the white space from the version history section - 10.08.17
V3.0 – FAQ updated for Street Class – 08.30.16
Last edited by Rhop101; 02-12-2018 at 01:06 PM.
The following 2 users liked this post by Rhop101:
bergi85 (02-01-2017),
indys2kautocrosser (01-05-2017)
09-06-2016, 06:53 PM
#136
On brake pads: I believe the Hawk Street/Racer pads are legal. They are the street version of the DTC30 and work from low temperatures. Very controllable with a high coefficient of friction for a street pad, they can easily handle anything an RE71r can deliver. Both my feedback and from nationally competitive drivers who have driven my car.
On anti-roll bars: The Karcepts is a very clever design. It has a quick broad range of adjustment. The spined torsion bars are available in a broad range of stiffnesses. I'm on the 0.188" wall thickness hollow bar one hole from the stiffest setting. It is also available with 0.120" wall thickness, .250" wall thickness, solid, and solid stepped up to 1.375" in the center (the spines are all 1.25. The range is 25% stiffer than the CR bar on the softest setting of the softest bar, to 500% on the stiffest setting of the stiffest bar. My setting is about 265% stiffer.
The arms are gorgeous machined aluminum. While the kit is $675, additional torsion bars in different sizes are $150 each. A rear bar is also available if moving to a modified class.
On shocks: The stock shocks are mono-tube designs. The Koni's are twin-tube with valving, according to Angelo Zarra of ANZE Engineering, dates from 1946. Given the stock ride height and springs of the Street classes, do they really have an advantage?
Penske 7500 Double Adjustables should be under $3400 and should work at stock ride heights. I believe ANZE, Penske, Kaz Technologies, and Ankeny all can valve them for autocross. Ankeny has also valved relatively inexpensive Bilstein PSS shocks for autocross. I believe Bilstein will also revalve them.
On anti-roll bars: The Karcepts is a very clever design. It has a quick broad range of adjustment. The spined torsion bars are available in a broad range of stiffnesses. I'm on the 0.188" wall thickness hollow bar one hole from the stiffest setting. It is also available with 0.120" wall thickness, .250" wall thickness, solid, and solid stepped up to 1.375" in the center (the spines are all 1.25
. The range is 25% stiffer than the CR bar on the softest setting of the softest bar, to 500% on the stiffest setting of the stiffest bar. My setting is about 265% stiffer. The arms are gorgeous machined aluminum. While the kit is $675, additional torsion bars in different sizes are $150 each. A rear bar is also available if moving to a modified class.
On shocks: The stock shocks are mono-tube designs. The Koni's are twin-tube with valving, according to Angelo Zarra of ANZE Engineering, dates from 1946. Given the stock ride height and springs of the Street classes, do they really have an advantage?
Penske 7500 Double Adjustables should be under $3400 and should work at stock ride heights. I believe ANZE, Penske, Kaz Technologies, and Ankeny all can valve them for autocross. Ankeny has also valved relatively inexpensive Bilstein PSS shocks for autocross. I believe Bilstein will also revalve them.
01-18-2017, 08:11 AM
#137
Id like to bump this awesome thread and add my 2 cents from the last few years of autocross experience in B Stock/Street.
I've listed two links to my local clubs last two months results. AKA Why a new guy or gal wanting to get into this sport should listen.
Summary Results, #1 - CENLA January Autocross - Sun 01-08-2017
Final Raw Time Results - CENLA December Autocross - Sun 12-11-2016
2002 AP1 (195k on the clock) Running in B Street
Number one mod above all: SEAT TIME!
Number two: Seat position! (move it up!)
Current mods: Cat back(cheap ebay),
RE71s(225s on all 4, best tire I've found so far)
Koni Yellows(full hard in front, half turn off full hard in rear)
Karcepts front bar(on third setting)
Hawk hp+ pads
Don't be frustrated when a little red Miata beats you bad first time out. It takes practice and lots of time behind the wheel to shred seconds off. In tight turns remember, brake, turn, gas. After each run, think about what you did wrong and what you can do on the next run to go a little faster. Good luck out there. So much fun!
I've listed two links to my local clubs last two months results. AKA Why a new guy or gal wanting to get into this sport should listen.
Summary Results, #1 - CENLA January Autocross - Sun 01-08-2017
Final Raw Time Results - CENLA December Autocross - Sun 12-11-2016
2002 AP1 (195k on the clock) Running in B Street
Number one mod above all: SEAT TIME!
Number two: Seat position! (move it up!)
Current mods: Cat back(cheap ebay),
RE71s(225s on all 4, best tire I've found so far)
Koni Yellows(full hard in front, half turn off full hard in rear)
Karcepts front bar(on third setting)
Hawk hp+ pads
Don't be frustrated when a little red Miata beats you bad first time out. It takes practice and lots of time behind the wheel to shred seconds off. In tight turns remember, brake, turn, gas. After each run, think about what you did wrong and what you can do on the next run to go a little faster. Good luck out there. So much fun!
Last edited by williamb81; 01-18-2017 at 11:49 AM.
The following users liked this post:
bergi85 (02-01-2017)
02-01-2017, 02:08 PM
#138
Couple of questions. I ran BS last season, and will be there this season as well.
"Number two: Seat position! (move it up!)"
What do you mean by this? How tall are you? I am 6'3" and have to have the seat back all the way.
"RE71s(225s on all 4, best tire I've found so far)"
I also ran RE71rs and I loved them. What size were you running? I could only get them (and i think there is only the one size for us) in 225/50r16.
"Karcepts front bar(on third setting)"
Have you ran the Small Fortune bar? I might be buying one from a local guy, just curious on the differences.
Thanks for all the info!
"Number two: Seat position! (move it up!)"
What do you mean by this? How tall are you? I am 6'3" and have to have the seat back all the way.
"RE71s(225s on all 4, best tire I've found so far)"
I also ran RE71rs and I loved them. What size were you running? I could only get them (and i think there is only the one size for us) in 225/50r16.
"Karcepts front bar(on third setting)"
Have you ran the Small Fortune bar? I might be buying one from a local guy, just curious on the differences.
Thanks for all the info!
02-06-2017, 08:20 AM
#139
That's tough being 6'3".. There is a theoretical best position knees bent slightly don't interfere with my hands, can rest wrist on steering wheel to set torso distance. I'm 6'0" tend to find I actually prefer sitting farther back to get more feedback from the rear tires, increase the rear weight bias, and it gives my legs room to easily retract from the pedals and use the seat bolsters to hold me in place for effectively.
Sitting closer speeds reaction times slightly for braking with stock pads and you get a little more leverage on the steering wheel, but that closer setting position has made it harder for me to release the clutch properly and the car is slightly pushier, the AP1s seem less pushy when I drove one.
For my Honda fit sitting closer was noticeably better, but everything was squishy pedalwise in that car.
The small fortune bar "Gendron" is very similar in assembly and sway bar rates, the Karcepts bar is just easier to adjust and assemble as its much less likely to interfere with suspension bits, though to use the Karcepts quick adjustment you have to flip the shocks left to right. If you can get a used Gendron for cheaper, go for it. Its not a night and day difference. Inside the FAQ there should be a Gendron bar section...
This year there are more new tires from the other brands so there may be more choices in other tire brands. I haven't checked.
Sitting closer speeds reaction times slightly for braking with stock pads and you get a little more leverage on the steering wheel, but that closer setting position has made it harder for me to release the clutch properly and the car is slightly pushier, the AP1s seem less pushy when I drove one.
For my Honda fit sitting closer was noticeably better, but everything was squishy pedalwise in that car.
The small fortune bar "Gendron" is very similar in assembly and sway bar rates, the Karcepts bar is just easier to adjust and assemble as its much less likely to interfere with suspension bits, though to use the Karcepts quick adjustment you have to flip the shocks left to right. If you can get a used Gendron for cheaper, go for it. Its not a night and day difference. Inside the FAQ there should be a Gendron bar section...
This year there are more new tires from the other brands so there may be more choices in other tire brands. I haven't checked.
The following users liked this post:
bergi85 (02-07-2017)
02-06-2017, 10:42 AM
#140
The small fortune bar "Gendron" is very similar in assembly and sway bar rates, the Karcepts bar is just easier to adjust and assemble as its much less likely to interfere with suspension bits, though to use the Karcepts quick adjustment you have to flip the shocks left to right. If you can get a used Gendron for cheaper, go for it. Its not a night and day difference. Inside the FAQ there should be a Gendron bar section...
Meanwhile, the machined aluminum arms and brackets of the Karcepts bar are a work of art and the curved arm concept extremely clever.
The following users liked this post:
bergi85 (02-07-2017)