[SCCA] Solo II Street Touring Category

This is an unofficial transcription of Section 17 of the 2003 SCCA National Solo Rules. (Copyright Sports Car Club of America 2003; all rights reserved;) It is believed to be correct, but any questions should be referred to the official rules as published by the SCCA. Order your own copy here.

Changes since the 2002 Rules are shown like this;
Further changes from FasTrack are shown like this.



    The Street Touring category of vehicle modifications is meant to fit between the current Stock and Street Prepared categories.  This category provides an natural competition outlet for auto enthusiasts using affordable sport sedans equipped with common suspension, engine,  and appearance modifications which are fully legal and compatible for street use anywhere in the country.  "Dress-up" items such as chrome dipsticks and non-standard filler caps are permitted, provided they serve no other purpose.

    Vehicles for this category include all coupes/sedans with a minimum of four seats, four seat belts; that are not sports car based, with a maximum engine displacement of 3.1 liters, normally aspirated and certain small displacement turbocharged sedans.  No limited slip differentials are permitted except for factory standard viscous coupler type units.

    A sports car based vehicle would include those that are 2+2 variants of 2 seat sports cars.


    1. All vehicles meeting the above criteria
    2. Volkswagen Golf/Jetta/Beetle/Passat 1.8T
    3. Volkswagen Jetta TDI, Golf TDI
    4. Audi A4 1.8T, non-Quattro
    5. Mazda 323 GTX(awd)
    6. Mazda 323 GT
    7. Volvo S40 and V40


    Porsche, all
    Datsun Z car 2+2
    Honda CRX
    Mazda RX-8 
    MGB GT
    Triumph, all
    This category consists of two classes:

    Under the provisions of Section 1.1 of these rules, regions are free to allow the previously-listed STR class or any other version of the ST concept which meets their local needs.

    If these rules contain errors, oversights, or omissions, the Solo Events Board and the National Office will make the necessary corrections through use of Technical Bulletins in SportsCar magazine at the earliest possible date.


    1. All Solo II Rules Stock Category allowances and the modifications that follow:
    2. A. Equipment and/or specifications may be exchanged between different years and models of a vehicle if:

    3.     (1) the item is standard on the year/model from which it was taken,
          (2) the years/models are listed on the same line of Appendix A (Street Prepared Classes)
      The updated/backdated part or the part to which it is to be attached may not be altered, modified, machined, or otherwise changed to facilitate the updating/backdating allowance.  The updating and/or backdating of engines, transmissions, or transaxles must be done as a complete unit as available from the factory, including those items required by emissions regulations for a particular configuration.  Example:  the Neon throttle body used on automatic transmission cars cannot be used on a manual transmission car.  Component parts of these units may not be interchanged.  Cars not listed in the Street Prepared sections of Appendix A may not be updated/backdated until approved by the SEB and published in SportsCar magazine.
    4. Air conditioning systems may be removed in whole or in part. This rule should not be interpreted to allow modification of the heater system.

    17.2. BODY WORK

    1. Pedal kits and other interior cosmetic accessories may be added.
    2. Any fully padded and upholstered front seats with reclining seat backs, rear seats may not be removed.
    3. Removal of factory trim (rub strips, emblems)
    4. Alternate steering wheels are allowed except that steering wheels with an integral airbag may not be changed.
    5. Fenders may not be cut or flared but the inside lip may be rolled in order to gain tire clearance. Flares that are part (left out of rulebook for 2003, but I predict it will return...Ed.) of body kits may be attached to the stock fenders. The intention is to allow cars to maximize tire width up to the maximum allowable size. No other changes to the stock fenders or wheel wells are permitted.
    6. Spoilers, body kits, rear wings, etc.

    17.3. TIRES

    17.4. WHEELS

    1. Any wheels up to 7.5" in width that fit over stock brakes


    1. Shock absorber bump stops may be altered or removed.
    2. Any shock absorbers may be used, provided they attach to the original mounting points. The number of shock absorbers shall be the same as Stock. No shock absorber may be capable of adjustment while the car is in motion, unless fitted as orignal equipment. MacPherson strut equipped cars may substitute struts, and/or may use any insert. This does not allow unauthorized changes in suspension geometry or changes in attachment points (e.g., affecting the position of the lower ball joint or spindle).  It is intended to allow the strut length changes needed to accommodate permitted modifications which affect ride height and suspension travel.

    17.6. BRAKES

    1. Cross drilled or slotted brake rotorsare permitted, same size and type as standard.
    2. Alternate DOT approved flexible brake lines.
    3. Air ducts may be fitted to the brakes, provided that they extend in a forward direction only, and that no changes are made in the body/structure for their use.  They may serve no other purpose.

    17.7. ANTI-SWAY BARS

    1. Any anti-sway bar is permitted. Bushing material, method of attachment, and locating points are unrestricted. This does not authorize removal of a welded-on part of a subframe toa ccommodate the installation. Components such as anti-roll bars and strut housings which serve dual purposes by also functioning as suspension locators may not be modified in ways which change the suspension geometry or steering geometry

    17.8. SUSPENSION

    1. Ride height may only be altered by suspension adjustments, the use of spacing blocks, leaf spring shackles, torsion bar levers, or change or modification of springs or coil spring perches. This does not allow the use of spacers which alter suspension geometry, such as those between the hub carrier and lower suspension arm. Springs must be of the same type as the original (coil, leaf, torsion bar, etc.) and except as noted herein, must use the original spring attachment points. Coil spring perches originally attached to struts or shock absorber bodies may be changed or altered, and their position may be adjustable. Spacers are allowed above or below the spring.  This permits multiple coil springs, as long as they use the original mount locations.
    2. Suspension bushings may be replaced with bushings of any materials (except metal) as long as they fit in the original location. Offset bushings may be used. In a replacement bushing the amount of metal relative to the amount of non-metallic material may not be increased. This does not authorize a change in type of bushing (for example ball and socket replacing a cylindrical bushing), or use of a bushing with an angled hole whose direction differs from that of the original bushing.  If the Stock bushing accommodated multi-axis motion via compliance of the component material(s), the replacement bushing may not be changed to accomodate such motion via a change in bushing type, for example to a spherical bearing or similar component involving internal moving parts. Pins or keys may be used to prevent the rotation of alternate bushings, but may serve no other purpose than that of retaining the bushing in the desired position.
    3. On vehicles with strut-type suspensions, adjustable camber plates may be installed at the top of the strut, and the original upper mounting holes may be slotted. The drilling of holes in order to perform the installation is permitted. The center clearance hole may not be modified. Any type of bearing or bushing may be used in the adjustable camber plate attachment to the strut. The installation may incorporate an alternate upper spring perch/seat and/or mounting block (bearing mount). Any ride height change resulting from installation of camber plates is allowed.  Caster changes resulting from the use of camber places are permitted
    4. Addition or replacement of suspension stabilizers (linkage connecting axle or De Dion to the chassis which controls lateral suspension location) is permitted. Traction bars or torque arms may be added or replaced. A Panhard rod may be added or replaced. Methods of attachment and attachment points are unrestricted.
    5. Camber kits may be installed on vehicles that do not have McPherson strut type suspensions. These kits may include replacement control arms or other parts that are designed specifically to compensate for camber changes resulting from lowering the car. These parts must use the original attachment points.
    6. Changes in alignment parameters which result directly from the use of allowed components are permitted.  For example, the dimensional changes resulting from the use of a cylindrical offset bushing which meets the restrictions of 17.8.B (there is no 3.E -- Ed.) are allowed, including those resulting from a change in the pivoting action to

    7. (a) about the mounting bolt, or
      (b) about the bushing itself.
    8. Strut bars are permitted with all types of suspension. Strut bars may be mounted only transversely across the car from upper right to upper left suspension mounting point and from lower right to lower left suspension mounting point. No other configuration is permitted. Additional holes may be drilled for mounting bolts. Only bolt-on attachment is permitted.


    1. The make, model number, and size of the battery may be changed but not its voltage. Relocation of the battery or batteries is permitted but not into the passenger compartment. If the battery is relocated and the original battery tray can be removed by simply unbolting it, the tray may be removed, or relocated with the battery.  Holes may be drilled for mounting or passage of cables. Longer cables may be substituted to permit relocation. The number of battery or batteries may not be changed from stock. The area behind the rearmost seat is not considered to be within the passenger compartment.

    17.10. ENGINE

    1. Engine and transmission must remain unmodified, including emissions equipment, except as noted below:
    2. Alternate air cleaner enclosures up to carburetor or throttlebody.  This does not allow any changes to intercoolers.
    3. Headers, emissions-legal.
    4. The engine management system parameters and operations may be modified only by the methods listed below.  Any and all modifications must meet or exceed the applicable US DOT emissions standards for the year, make, and model of the car.  These allowances also apply to forced induction cars, except that no changes to standard boost levels, intercoolers, or boost controls are permitted. 
      1. Reprogrammed ECU may be used in the standard housing.  Traction control parameters may not be altered.
      2. Electronic components may be installed inline between an engine's sensors and ECU.  These components may alter the signal coming from the sensor in order to affect the ECU's operation of the engine management system.  Example: fuel controllers that modify the signal coming from an airflow sensor.
      3. Fuel pressure regulators may be replaced in lieu of electronic alterations to the fuel system.  It is not permitted to electronically modify the fuel system AND replace a fuel presure regulator.
      4. Ignition timing may be set at any point on factory adjustable distributor ignition systems.
      5. VTEC controllers and other devices may be used which alter the timing of factory standard electronic variable valve timing systems.
      6. The mass airflow sensor must remain in its approximate original location.
    5. All STS vehicles must comply with the Federal 49-state safety and tailpipe emissions test requirements as a minimum.  

    6. Short throw shift kits may be installed.
    7. Any accessory pulleys and belts of the same type (e.g., V-belt, serpentine) as standard may be used.  This allowance applies to accessory pulleys only (e.g., alternator, water pump, power steering pump, and crankshaft drive pulleys).  It does not allow replacement, modification, or substitution of pulleys, cogs, gears, or belts which are part of cam, layshaft, or ignition drive or timing systems, etc.  Any crankshaft damper or pulley may be used.  SFI-rated dampers are recommended.  Supercharged cars may not change the effective diameter of any pulley which drives the supercharger.

    17.11. STX

    1. The STX class expande the vehicle eligibility limits beyond those specified for STS, and adds a limited number of allowed modifications.  The allowances are as follows:
    1. All allowances in STS carry over, including street tires, emissions, etc.

    2. All restrictions regarding body type carry over.

    3. Engine size allowance: up to 5.1, normally aspirated and 2.0, forced induction (single turbo or supercharger).

    4. Rim restriction: maximum width of 8", diameter/offset unrestricted.  Tire restriction: max width 245 mm .

    5. Only factory limited slip differentials (LSD) are allowed on AWD vehicles, as defined in Section 12.4. For AWD vehicles that did not come with any type of limited slip differential (including center differential or transfer case), a single aftermarket LSD may be added.  2WD vehicles may use any LSD unit. 

    6. High flow catalytic converters are allowed, but must attach within six inches of the original unit.  Multiple catalytic converters may be replaced by a single unit, provided the single unit is within six inches of the original primary unit.  The resultant configuration must meet Federal emissions standards at normal vehicle operating temperature.

    7. Alternate motor mounts and/or engine locators (bobble struts) sold by the vehicle's manufacturer or their Motorsports subsidiary or affiliate ( Chrysler/Mopar, Toyota/TRD , Honda/Mugen, etc.) are allowed.  

    8. Alternate driver and front passenger seats are allowed, but they cannot be constructed of a solid outer shell and must have a suspended bottom cushion and be fully upholstered.

    9. Brake rotors and calipers are unrestricted, but must attach to the original attachment points.

    10. Additionally excluded cars: BMW M3 (E36 and E46), BMW M5 (all), Mitsubishi Evo 8, Subaru Sti.

    ...Jerry Mouton || jerry@moutons.org || Last modified 11/23/03