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Car Classing Guide + Help Thread


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Updated April 2023

 

Autocross car classes are based on the SCCA Solo program. (A copy of the most recent 2020 SCCA SOLO NATIONAL RULES can be found here: https://www.scca.com/downloads/66191-2023-solo-rule-bookv1/download

 

Visit the SCCA Autocross section for any additional info: https://www.scca.com/pages/solo-cars-and-rules

 

Here is a quick Breakdown of the all the SCCA car classes and what category they fall under, I have also included the pages where the requirements are explained and which cars are eligible for which class.

 

SCCA Car Categories and Classes

 

Street (Starts on p.73 of the 2023 rule book)

SS, AS, BS, CS, DS, ES, FS, GS, HS

 

Solo Spec Class Additional info at ( starts on p.173 of the 2023 rule book)

SSC

 

Street Touring (ST) (Starts on p.85 of the 2023 rule book)

SST, STU, STR, STX, STS, STH,

 

Street Prepared (SP) (Starts on p.98 of the 2023 rule book)

SSP, CSP, DSP, ESP, FSP

 

Street Modified (SM) (Starts on p.119 of the 2023 rule book)

SM, SSM, SMF

 

Prepared (P) (Starts on p.125 of the 2023 rule book)

XP, CP, DP, FP, EP,

 

Modifed (M) (Starts on p.149 of the 2023 rule book)

AM, BM, CM, DM, EM, FM, FSAE

Classic American Muscle (CAM):  Additional info at https://www.scca.com/downloads/65394-2023-cam-and-xtreme-rules-draft-includes-cam-xs-ev-v12/download

CAM-C, CAM-T, CAM-S

Extreme Street (XS): Additional info at: https://www.scca.com/downloads/65394-2023-cam-and-xtreme-rules-draft-includes-cam-xs-ev-v12/download

XS-A, XS-B. XS-S

 

How Car Classes are Divided into Groups for the WSCC

 

1. Street
Only the following classes are eligible for competition under this group:  SS, AS, BS, CS, DS, ES, FS, GS, HS.

 

2. SCCA Mixed
This grouping is used for all competitors with cars classed under Street Touring: STU, STR, STX, STS, STH

This group also includes any cars with R-compound tires or tires with a tread rating of 200TW and bellow. All racing tire or tires below 200tw  will have the "R" prefix added. Example: "SMF" becomes "SMF-R".

3. Modified on Street Tire
To compete in this group you must have a car that falls under Street prepared (SP), Street Modified (SM) Prepared (P) or Modified (M) categories but your tires must be street tires with a tread rating of 200 or more. This group caters to competitors with highly modified cars using street tires. The prefix "S" is added to each car class using street tires,  example "BSP" becomes "BSP-S"

4. Novice
Driver that have competed in less than 8 events prior to the start of the 2023 season are eligible to complete in the Novice class. Competitors must class their cars based on the classing guide listed above. All SCCA classes are eligible for this group.

 

CAR CLASSING LOOKUP: Cars allocated to their respective classes with the Appendix A section of the rule book. (page 179 in the 2023 rule book)

*hint "control F" will bring up the search function in PDF, use it :)

2023 PAX factors for each class: http://solotime.info/pax/index.html

 

If you are still unsure how to class your car please use AM (A-Modified) or please post below if you need help.

 

2023 season update completed.

Edited by Magner
2023 Season Update
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(Copied from the SCCA)

 

What class is my car in?

 

SCCA® Solo® has many categories divided into classes for vehicles. Those categories include:

 

Street

– This category includes mass-produced,common vehicles that may be “daily drivers” (cars used for normal, everyday driving). Stock Category cars compete in their “factory” configuration with a minimal number of allowances (not requirements).

 

Street Touring®

 – This class is a fairly new class and is geared towards cars with common bolt-on modifications. Things like cold-air intakes, headers, lowering springs, etc. This is the only category that does not allow DOT competition R-compound tires – only high performance tires with a UTQG treadwear rating of 140 or higher are allowed (found on the tire sidewall). 2 of 3

 

Street Prepared

– This is the original Solo® “street” class, sometimes called a “bolt-on” class. Any fuel and ignition system is allowed along with any suspension springs and shocks/struts as long as they are fitted into their original location. Things like turbo/superchargers must remain the same. There is no limit on  wheel size or DOT tire sizes.

 

Street Modified

– This is the top tier of the “street” classes. This class allows engine swaps as long as the engine is made by the same manufacturer as the car. You may also add turbo/super chargers, camshaft upgrades, and any suspension upgrades as long as it uses the factory attachment points.

 

Prepared

– This class is generally for non-streetable cars. Things like gutted

interiors and racing slicks are a big give away. Most things are allowed in this class and is relied on weight more than anything.

 

Modified

– They are usually special built competition vehicles and most of them resemble an open-wheel Indy car or a closed-wheel LeMans sports racer. DM and EM cars may have started life on the streets, but just about any engine, drivetrain, or suspension is permitted. Supercharged rotary engines and V-8 engines are seen in 1700 pound EM machines and powerful 4-cylinders are common in 1300-pound DM lightweights.

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Hello. Last year I was hoping to autocross my Fiat 500 Turbo but it was brought to my attention that my car did not meet the stability requirement. I've noticed that my car is now listed in the 2014 Solo rules under the Street Touring Compact class. Is my car now allowed run in this class in stock form? Thanks.

 

Short Answer:

 

All Fiat 500 (Non-Abarth) are banned from Street class for reasons of stability. The FIat 500 Turbo is ONLY allowed in STC IF and ONLY IF it can satisfy the stability issues that ban it from Street Class. In other words you can't just take a stock Fiat 500 and class it as STC. If will either need to be lowered or have the track widened. (lowering spring or wider wheel and tire combo) before it can compete.

 

Long Answer:

 

As per the 2014 SCCA rulebook section 3.1 (p.36) all cars in Solo Competition must have a favorable overall height to track width relationship. Meaning overly narrow and tall cars are not eligible because they have to potential of tipping over during autoslalom events. Page 168 also explicitly lists the non Abarth model Fiat 500 from competition in Street Classes. I can't answer any specific question on low much lower your specific car needs to be but the rule book should provide enough to find out.

 

If a vehicle is modified to the point where it can meet the minimum guidelines set in place by the rule book it may be allowed to compete. Such is the case with all Non-Abarth Fiat 500s. If the vehicle is lowered or the track is widened with wider wheels and tires or more pronounced offset it may compete in Street Touring Compact (STC). Cars excluded from a class for reasons of stability may not compete in any other car classes unless they can first prove the meet the minimum height vs width ratio.

 

The following Cars are excluded from Street Category for 2014:

 

Dodge Caliber (non-SRT)
Fiat 500 (non-Abarth)
GEO Tracker & Suzuki Sidekick
Jeep CJ series
MINI Countryman
Nissan Juke
Suzuki Samurai
Scion xB (2004-06)

Scion IQ

*Common sense should also be applied: Ex: just because a Honda CRV isn't listed doesn't mean it's legal.

 

These rules are important to follow for a few reasons: A) Safety is always the first priority. B) Due diligence, if something was ever to happen locally due to the club not taking necessary actions to prevent it C) it has happened before, there have been accidents in the US related to cars not meeting the requirements tipping over. D) our lot is very bumpy and could have the potential to launch a car up on 2 wheels. (I've seen it happen more than once here)

 

the

 

Just a quick question -

 

Regarding RHD vehicles... is there a change to how they are classed? 

page 105 of the 2014 solo rulebook which I believe is the correct one..

http://scca.cdn.racersites.com/prod/assets/2014%20Solo%20Rules%20Book%207%20w%20cover%20and%20links.pdf

is the only page with "JDM" on it - (under street modified)

 

now my RHD vehicle would be under street prepared otherwise, but being its a RHD it falls not under street modified, but just Prepared, or Modified? Im confused how it says Excluding JDM-spec cars on the street modified page above, so where does it fit as there seems to be no definitive place for jdm vehicles, specifically ones that are essentially not modified.

 

 

Short Answer:

 

JDM (right hand drive cars) are allowed LOCALLY in any Street Modified (SM) Classes they qualify for. If a JDM car have modifications not allowed in SM they will go back to EM or DM where they are officially classed in the SCCA rule book.

 

Long Answer

 

If you consult the 2014 SCCA rule book you will find no JDM cars are classed. This is because the rules only allow cars sold for sale in North America to compete.  Cars sold overseas have different options and engine choices that would give them unfair advantages over the North America counter parts. It it far too time consuming to analyze each car and figure out what sub car class it would fall under. As a result, every car class group: Street, Street Touring (ST) Street Prepared (SP) Street Modified (SM) and Prepared only allow cars sold in North America.

 

The exception is the Modified car class group. In this group almost anything goes. The offical SCCA rules still allow JDM cars in this group because there is no restriction on where the car was originally sold. A very simplistic view of the rules for this group would have the cars classed as follows: If the engine displacement is over 2000cc it would fall under E-Modified (EM). If the engine is under 2000cc it would fall under D-Modfied (DM).

 

In 2013 the WSCC supplemental rules were changed to allow cars not sold in North America a chance to compete locally in Street Mofided class. We did this because the local popularity of these cars we made a concession to allow them were they would A) It was easy to class and not disrupt competition with the rules already set in place. B) SM group is extremely easy to sub class vsarious cars.

 

JDM Street Modified Sub Classing Guide:

 

1. Read the 2014 Street Modified Rule Book, If the modifcation on the car are approved proceed to 2. (if not class it to EM or ED)

2. Is it a front wheel drive car? YES = Street Modified Front Wheel Drive (SMF)

3. When the car was made did it only have 2 seats? YES = Super Street Modified (SSM)

4. If it's not FWD and has more than 2 seats = Street Modifed (SM)

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  • 3 weeks later...

My 92 Civic Si (non-turbo) has the following:

- Koni Yellows on coilovers

- short shifter

- front and rear strut bars

- some Hyperflex suspension bushings

- deleted cat

- 205/50-15" tires

 

I believe this allows me to run in STC.  Correct?

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My 92 Civic Si (non-turbo) has the following:

- Koni Yellows on coilovers

- short shifter

- front and rear strut bars

- some Hyperflex suspension bushings

- deleted cat

- 205/50-15" tires

 

I believe this allows me to run in STC.  Correct?

Removal of Cat converters are NOT allowed in any ST class. You can however replace it with any other cat or move it up to 6" from it's original mounting location. It's also required by law in Manitoba.

 

Cat rules are listed on page 86 of the 2014 SCCA Solo rulebook, section 14.E. if you need more details

 

Technically without the cat you would be classed under FSP.

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Removal of Cat converters are allowed in any ST class.

 

I assume you meant "isn't" allowed..

 

Full cat rules are listed on page 86 of the 2014 SCCA Solo rulebook, section 14.E.

 

 

This didn't mention "removal" so I interpreted "any catalytic converter" to include "none".

 

It doesn't really matter to me where I'm classed, but accurately would be nice.  I'm not looking for and "edge" or anything, so FSP is fine by me.

 

Thanks again, Chris.

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Removal of Cat converters are NOT allowed in any ST class.  It's also required by law in Manitoba.

 

This is from MPI's Light Vehicle Inspection Methods and Standards manual...

 

Inspection of.. "catalytic converter – (Applies to motor vehicles manufactured on or after January 1,1995)``

 

When I had my exhaust done, the shop told me they could remove the cat as the car was of sufficient age, so I don`t believe I`m in noncompliance of Manitoba law...at least not in this regard ;)

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  • 3 weeks later...

So I'm planning on running in B-Street this season in my AP1 S2000. Today, I finally replaced my valve retainers with AP2 retainers. For those who are not familiar with S2000's, cracked AP1 intake valve retainers is a common problem and it's recommended to swap them out with AP2 retainers. My car is now completely stock other than the retainers. Obviously if you want to get technical changing retainers puts you out of Street class based on SCCA rules. But I was wondering, if the WSCC members and fellow autocrossers would be okay with me running in B-Street since this really just a reliability upgrade.  :)

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So I'm planning on running in B-Street this season in my AP1 S2000. Today, I finally replaced my valve retainers with AP2 retainers. For those who are not familiar with S2000's, cracked AP1 intake valve retainers is a common problem and it's recommended to swap them out with AP2 retainers. My car is now completely stock other than the retainers. Obviously if you want to get technical changing retainers puts you out of Street class based on SCCA rules. But I was wondering, if the WSCC members and fellow autocrossers would be okay with me running in B-Street since this really just a reliability upgrade.  :)

No problem at all. The new retainers are actually about 15% heavier so there's no performance advantage.

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class help please, 1994 bmw m3 with full coilovers, upgraded front sway bar and links, rear trailing arm limiters, delrin front control arm bushings, hp plus brake pads, aftermarket wheels on z2's. Been running not yet classed for 

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Judging by your mod list everything looks like it would fall under Street Touring. Not sure about the rear trailing arm limiters since I have no idea what that is.

 

P. 196 of the 2014 SCCA Solo Rule book is showing the M3:

 

Looks like the only BMW M3 listed in STX is the E30 chassis. All E36 M3 (your model) and E46 M3's are listed under STU 2wd.  The only expection is for the "real" Euro spec M3, those would fall under SM-S. 

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  • 2 weeks later...
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Hey there all,

Just would like to confirm if I have picked the correct classification for my car.

2010 Ford Fusion Sport, stock suspension, oversize performance tires, CAI, tune, cat back exhaust. Looks to me like GSR.

Is this correct?

Royce

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the tune and CAI would move you out of street class. What kind of tires are they? if they are DOT and have a tread wear rating of 140 or higher then you would not be in R. Sounds more like STX if its the 3.5L. R rated tires would put you in DSP

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