STX Ruleset

Below are the applicable rules that define this build, excerpted from the 2010 SCCA Solo rulebook.  It takes a bit of reading comprehension (a phrase I use here not sarcastically) to really get all of this.  For the amateur rulebook readers in the audience, the overriding thing to remember here is, “if it doesn’t say you can, then you can’t”.  When I show up to my first race in the car, every single thing that’s changed from when it rolled off the showroom floor in 1967 must be accounted for by one of the rules that follow.

I’ve  placed the Street Touring category rules first, as they are most relevant.  They “build” on the Stock rules that follow.

The Street Touring category of vehicle modifi cations is meant to fi t be-
tween the current Stock and Street Prepared categories. This category
provides a natural competition outlet for auto enthusiasts using afford-
able sports cars and sedans equipped with common suspension, en-
gine, and appearance modifi cations which are fully legal and compat-
ible with street use anywhere in the country
Vehicle eligibility lists are now in Appendix A.
Under the provisions of Section 1.1 of these rules, Regions are free
to allow any other version of the ST concept which meets their local
See Sections 3.8 and 8.3 for documentation requirements.
All Solo Rules Stock Category allowances, plus all allowances con-
tained in 14.1 through 14.10.
A. Pedal kits and other interior cosmetic accessories may be added.
“Dress-up” items such as chrome dipsticks and non-standard fi ller
caps are permitted, provided they serve no other purpose.
B. The driver and front passenger seats may be replaced, with the fol-
lowing restrictions: The seating surface must be fully upholstered.
The top of the seat, or an attached headrest, may not be below the
center of the driver’s head. The seat, including mounting hardware,
must weigh at least 25 pounds and must be attached using the OE
body mounting holes/studs. Additional mounting points may be add-
C. Factory rub strips, emblems, and mud fl aps may be removed.
D. Alternate steering wheels are allowed except that steering wheels
with an integral airbag may not be changed.
E. Fenders may not be cut or fl ared but the inside lip may be rolled
to gain additional tire clearance. (The outer fender contour may not
be changed.) Flares that are part of body kits may be attached to
the stock fenders. Plastic and rubber wheel well splash shields may
be modifi ed for tire clearance and to accommodate a rolled inside
fender lip. The intention is to permit fi tting the maximum allowable
tire size, and the modifi cations may serve no other purpose (e.g. air
intake, brake ducts, etc.). No other changes to the stock fenders or
wheel wells are permitted.
F. Addition of spoilers, splitters, body kits, rear wings and nonfunctional
scoops/vents is allowed. The intent of this allowance is to accommo-
date commonly available appearance kits, and replicas thereof, which
have no signifi cant aerodynamic function at Solo speeds. Body kits
are limited to bumper covers (including modifi ed OE bumper covers),
valances, side skirts, and fender fl ares. Standard parts may not be
removed except for the substitution of spoilers, rear wings, bumper
covers and valances. Rear wings must attach only aft of the rear
wheel centerline.
The allowances regarding wings and spoilers only allow swapping
like for like if the original device was not an OE option as confi gured
by the factory, i.e. a spoiler for a spoiler or a wing for a wing. If a
vehicle is available without a wing or spoiler from the manufacturer
then either can be installed.
Surface area of all splitters, spoilers and rear wing (see 12.9) shall
not exceed 5 square feet in sum total. Substitution of rear spoilers
or wings must retain any original third brake light functionality unless
otherwise equipped. No underbody panels may be added or substi-
tuted. The drilling of holes for the purpose of mounting these pieces
is permitted.
G. Strut bars may be added, removed, modifi ed, or substituted 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 confi guration is permitted. Additional holes may be drilled
for mounting bolts. Only bolt-on attachment is permitted. Interior trim
panels may be modifi ed to allow installation of strut bars. Holes or
slots may be no larger than necessary and may serve no other pur-
pose. This does not permit any modifi cations to the frame or unibody
beyond the allowed mounting holes.
H. Longitudinal (fore-aft) subframe connectors (“SFCs”) are permitted
with the following restrictions:
1. They must only connect previously unconnected boxed frame rails
on unibody vehicles.
2. Each SFC must attach at no more than three points on the uni-
body (e.g. front, rear, and one point in between such as a seat
mount brace or rocker box brace).
3. SFCs must be bolted in place and not welded.
4. No cutting of OE subframes or fl oorpan stampings is permitted.
Drilling is permitted for mounting bolts only.
5. No cross-car/lateral/triangulated connections directly between the
driver’s side and passenger’s side SFCs are permitted. Connec-
tions to OE components such as tunnel braces or closure panels
via bolts are allowed and count as the third point of attachment.
No alteration to the OE components is permitted.
6. SFCs may not be used to attach other components (including but
not limited to torque arm front mounts or driveshaft loops) and
may serve no other purpose.
14.3 TIRES
Tires must meet the eligibility requirements of the Stock category (ex-
cluding 13.3.F), with the following additional restrictions:
A. Tires may have section widths up to and including the following:
ST, STS, STR (AWD) – 225 mm
STX (AWD), STU (AWD) – 245 mm
STR (2WD) – 255 mm
STX (2WD) – 265 mm
STU (2WD) – 285 mm
B. Tires must have a minimum UTQG treadwear rating of 140.
C. Tire models must not appear on the following list, which may be al-
tered at any time by the SEB upon notifi cation of the membership.
Pirelli P Zero Corsa
Any wheels are allowed with widths up to the following:
ST, STS, STR (AWD) – 7.5”
STX (AWD) – 8.0”
STX (2WD), STR (2WD) – 9.0”
STU – unlimited
A. Shock absorber bump stops may be altered or removed.
B. Any shock absorbers may be used. Shock absorber mounting brack-
ets which serve no other purpose may be altered, added, or replaced,
provided that the attachment points on the body/ frame/subframe/
chassis/suspension member are not altered. This installation may
incorporate an alternate upper spring perch/seat and/or mounting
block (bearing mount). The system of attachment may be changed.
The number of shock absorbers shall be the same as Stock. No
shock absorber may be capable of adjustment while the car is in mo-
tion, unless fi tted as original 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 modifi cations which affect ride height and
suspension travel.
A. Cross drilled and/or slotted brake rotors may be fi tted (same size/
type/material as standard) provided all such voids are within the disc
area, and comprise no more than 10% of that area
B. Brake lines may be substituted with alternate DOT approved fl exible
brake lines.
C. Air ducts may be fi tted 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.
D. Original equipment ABS braking systems may be electrically dis-
abled, but may not be removed or altered in any other way.
E: STX and STU: Non-standard brake rotors may be used provided
they are of equal or larger dimensions (diameter and thickness)
and made of ferrous material (e.g. iron). Thickness includes the in-
dividual plates of a vented rotor, as well as the overall dimension.
Aluminum rotor hats are allowed. Cars originally equipped with solid
(non-vented) rotors may utilize vented rotors. Cross-drilled and/or
slotted brake rotors may be fi tted provided all such voids are within
the disc area, and comprise no more than 10% of that area. Brake
calipers and mounting brackets may be replaced provided they bolt
to the standard locations and the number of pistons is equal to or
greater than standard. A functioning emergency brake of the same
type, operation, and actuation as OE must be present. Drum brakes
may be replaced with disc brakes of a diameter equal to or greater
than the inside diameter of the standard drum. Such conversions
must be bolted, not welded, to the axle/trailing arm/upright, and must
include an integral, redundant emergency brake. Changes to back-
ing plates/dust shields/brake lines to accommodate these changes
are permitted but may serve no other purpose.
Substitution, addition, or removal of any anti-roll bar(s) is permitted.
Bushing material, method of attachment, and locating points are un-
restricted. Components such as anti-roll bars and strut housings that
serve dual purposes by also functioning as suspension locators may
not be modifi ed in ways that change the suspension geometry or steer-
ing geometry. Non-standard lateral members which connect between
the brackets for the bar, including allowed strut bars per 14.2.G, are
A. Ride height may only be altered by suspension adjustments, the
use of spacing blocks, leaf spring shackles, torsion bar levers, or
change or modifi cation of springs or coil spring perches. This does
not allow the use of spacers that 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. This permits multiple springs, as long as they use the original
mount locations. 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.
Suspension bump stops may be altered or removed.
B. Suspension bushings may be replaced with bushings of any mate-
rials (except metal) as long as they fi t in the original location. Off-
set bushings may be used. In a replacement bushing the amount
of metal relative to the amount of nonmetallic 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 replace-
ment bushing may not be changed to accommodate 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
C. The following allowances apply to 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 modifi ed. 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 instal-
lation of camber plates is allowed. Caster changes resulting from the
use of camber plates are permitted.
D. Differential mount bushings may be replaced, but must attach in the
factory location(s) without additional modifi cation or changes. Dif-
ferential position may not be changed. The amount of metal in a
replacement bushing may not be increased relative to the amount of
metal found in a standard bushing for the particular application. Solid
metal bushings are specifi cally prohibited.
E. Transmission mounts may be replaced, but must attach in the factory
location(s) without additional modifi cation or changes. Transmission
position may not be changed. The amount of metal in a replacement
mount may not be increased relative to the amount of metal found in
a standard mount for the particular application. Solid metal mounts
are specifi cally prohibited.
F. Steering rack bushings may be replaced, but must attach in the fac-
tory location(s) without additional modifi cation or changes. Steering
rack position may not be changed. The amount of metal in a replace-
ment bushing may not be increased relative to the amount of metal
found in a standard bushing for the particular application. Solid metal
bushings are specifi cally prohibited. This does NOT allow shimming
or otherwise relocating the steering rack.
G. Camber bolts may be installed providing these parts use the original,
unmodifi ed mounting points and meet the restrictions specifi ed in
14.5.B. Caster changes resulting from the use of camber bolts are
H. Solid axle suspension allowances:
1. Addition or replacement of suspension stabilizers (linkage con-
necting the axle housing or DeDion to the chassis, which controls
lateral suspension location) is permitted.
2. Traction bars or torque arms may be added or replaced.
3. A Panhard rod may be added or replaced.
4. The upper arm(s) may be removed, replaced, or modifi ed, and the
upper pickup points on the rear axle housing may be relocated.
5. The lower arms may not be altered, except as permitted under
14.8.B, or relocated. Methods of attachment and attachment
points are unrestricted, but may serve no other purpose (e.g.
chassis stiffening). This does not authorize removal of a welded-
on part of a subframe to accommodate the installation.
I. Camber kits, also known as camber compensators, may be installed.
These kits consist of either adjustable length arms or arm mounts
that provide a lateral adjustment to the effective length of a control
arm. Alignment outside the factory specifi cations is allowed. The fol-
lowing restrictions apply:
1. On double/unequal arm (e.g. wishbone, multi-link) suspensions,
only the upper arms OR lower arms may be modifi ed or replaced,
but not both. Non-integral longitudinal arms that primarily control
fore/aft wheel movement (e.g. trailing arm(s) or link(s) of a multi-
link suspension) may not be replaced, changed, or modifi ed.
2. On arm-and-strut (MacPherson/Chapman) suspensions, the lower
arms may be modifi ed/replaced OR other methods of camber ad-
justment as allowed by paragraphs 14.8.B, C, or G may be used,
but not both.
3. On swing or trailing arm suspensions, the main arms may not be
modifi ed or replaced, but lateral locating links/arms may be modi-
fi ed or replaced.
4. The replacement arms or mounts must attach to the original stan-
dard mounting points. All bushings must meet the requirements of
14.8.B. Intermediate mounting points (e.g. shock/spring mounts)
may not be moved or relocated on the arm, except as incidental
to the camber adjustment. The knuckle/bearing housing/spindle
assembly cannot be modifi ed or replaced.
Note: Many modern suspension designs known by other names,
actually function as double A-arm designs. These include the rear
suspensions on 88+ Honda Civic/Integra, Neon, E36 BMW, and
most “multi-link” and are covered by 14.8.I.1.
J. On strut-equipped cars, the strut’s lower integral mounting bracket,
for attachment to the upright or spindle, is unrestricted provided it
attaches to the stock location. Any resulting change to the position
of the strut centerline is allowed. Such brackets shall serve no other
purpose. This does not allow for changes to the integral steering arm
on cars that have the steering arm integrated with the strut body.
K. Changes in alignment parameters that result directly from the use of
the allowed components are permitted. For example, the dimension-
al changes resulting from the use of a cylindrical offset bushing that
meets the restrictions of 14.8.B are allowed, including those resulting
from a change in the pivoting action to:
(1) about the mounting bolt, or
(2) about the bushing itself.
L. Subframe mount bushings may be replaced, but must attach in the
factory location(s) without additional modifi cation or changes. Sub-
frame position may not be changed. The amount of metal in a re-
placement bushing may not be increased relative to the amount of
metal found in a standard bushing for the particular application. Solid
metal bushings are specifi cally prohibited.
A. 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. The area
under the rearmost seat is considered to be within the passenger
B. The addition of electrical grounding cables and associated distribu-
tion blocks/terminals is permitted. Holes may be drilled for mounting
only. This does not permit the use of electrical enhancement compo-
nents such as condensers, voltage controllers, etc.
Engine and transmission must remain unmodifi ed, including emissions
equipment, except as noted below. All emissions monitoring system
hardware and software must be operationally functional as originally
intended by the manufacturer. Tampering with emissions system soft-
ware and/or hardware to create or cloak non-compliance is not permit-
ted. Some examples of emissions system tampering are O2 foolers,
disabling or deactivating Check Engine Light (CEL) code indication,
backdating ECU internals from OBD2 to OBD1, etc.
A. Internal baffl ing of oil pans may be added or modifi ed. Addition or
modifi cation of windage trays, crankshaft scrapers, and oil pump
pickups is not allowed.
B. Original equipment traction control systems may be electrically dis-
abled, but not removed or altered in any other way.
C. The air intake system up to, but not including, the engine inlet may be
modifi ed or replaced. The engine inlet is the throttle body, carbure-
tor, compressor inlet, or intake manifold, whichever comes fi rst. The
existing structure of the car may not be modifi ed for the passage of
ducting from the air cleaner to the engine inlet. Holes may be drilled
for mounting. Emissions or engine management components in the
air intake system, such as a PCV valve, or mass airfl ow sensor, may
not be removed, modifi ed, or replaced, and must retain their original
function along the fl ow path.
D. Exhaust manifolds and headers (including downpipes) may be re-
placed with alternate units which are emissions-legal. Relocation of
the oxygen sensor on the header is permitted. Alternate oxygen sen-
sors, including heated types, are permitted. This allowance does not
permit relocation of the catalytic converter (see 13.10.E). Exhaust
heat shields which cover only (and attach solely to) the header/mani-
fold/downpipe are considered part of that component and may be re-
placed, removed, or modifi ed. All other exhaust heat shields may be
modifi ed the minimum amount necessary to accommodate allowed
alternate exhaust components.
E. Catalytic Converters
ST, STS, STR – Catalytic converters may be replaced by aftermarket
units. Replacements must:
1) Be certifi ed for use in that vehicle application by the manufac-
turer or reconditioner,
2) Bear correct EPA-mandated labeling,
3) Be of the OE quantity and type (i.e. oxidation, three-way, etc.)
4) Be used in the same location(s), relative to the chassis, as the
OE converter(s).
This does allow for high performance replacements, provided they
meet all restrictions herein.
STX, STU – Any high fl ow catalytic converter(s) are allowed, but
must attach within six inches of the original unit. Multiple catalytic
converters may be replaced by a single unit. The inlet of the sin-
gle replacement converter may be located no further downstream
than 6” along the piping fl ow path from the original exit of the fi nal
OE converter.
F. The engine management system parameters and operation may be
modifi ed only via the methods listed below. Any and all modifi cations
must meet or exceed the applicable EPA tailpipe emissions stan-
dards for the year, make, and model of the car. These allowances
also apply to forced induction cars, except that no changes to stan-
dard boost levels, intercoolers, or boost controls are permitted. Boost
changes indirectly resulting from allowed modifi cations are permis-
sible, but directly altering or modifying the boost or turbo controls,
either mechanically or electronically, is strictly prohibited.
1. Reprogrammed ECU (via hardware and/or software) may be used
in the standard housing. Traction control parameters may not be
altered. Altered engine controllers may not alter boost levels in
forced induction engines. Alternate software maps which violate
these restrictions may not be present during competition, regard-
less of activation.
2. Electronic components may be installed in-line between an en-
gine’s sensors and ECU. These components may alter the signal
coming from the sensor in order to affect the ECU’s operation of
engine management system. Example: fuel controllers that modify
the signal coming from an airfl ow sensor.
3. Fuel pressure regulators may be replaced in lieu of electronic al-
terations to the fuel system. It is not permitted to electronically
modify the fuel system AND replace a fuel pressure regulator.
4. Ignition timing may be set at any point on factory adjustable dis-
tributor ignition systems.
5. VTEC controllers and other devices may be used which alter the
timing of factory standard electronic variable valve timing sys-
6. All vehicles must comply with the EPA tailpipe emissions test re-
quirements as a minimum.
G. Any mechanical shift linkage may be used.
H. Any accessory pulleys and belts of the same type (e.g., V-belt, ser-
pentine) as standard may be used. This allowance applies to ac-
cessory pulleys only (e.g., alternator, water pump, power steering
pump, and crankshaft drive pulleys). It does not allow replacement,
modifi cation, 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.
I. Upper engine shields made of plastic material, the purpose of which is
to hide mechanical components in the engine compartment, may be
removed if they have a solely aesthetic and/or acoustic function.
J. Engine mounts may be replaced, but must attach in the factory
location(s) without additional modifi cation or changes. Engine po-
sition may not be changed. The volume of metal in a replacement
mount may not be increased relative to the volume of metal found
in a stock mount for the particular application. Solid metal mounts
are specifi cally prohibited. Any non-metallic inserts may be used.
All components between the engine and the mounting structure are
considered to be part of the motor mount assembly and therefore
comprise the motor mount.
Hydraulic shock type rear engine locators, or bobble struts may be
replaced by manufacturer’s performance part, or aftermarket replace-
ment part. This part must retain factory dimensions and attachment
points, including factory design. (Example: If factory locator/bobble
strut is gas or hydraulic piston type, replacement part must be gas or
hydraulic piston type. No solid mounts may be substituted.)
K. Limited Slip Differentials
ST, STS – No limited slip differentials are permitted except for factory
standard viscous coupler type units.
STX, STU, STR – Only standard (as defi ned in Section 12.4) limited
slip differentials (LSD) are allowed on AWD vehicles. 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.
Where a car is out of production and the manufacturer is either out of
business, stocks no parts or no longer has a required part, a part of any
origin but as similar as possible to the original may be substituted. The
entrant must be prepared to show documentary evidence that one of
the three circumstances above applies and that the substituted part is
as similar as possible under the circumstances. Substitute parts which
provide improvements in performance (e.g. superior gearing, lighter
weight, better camshaft profi le, etc.) are not permitted under this allow-


And the Stock rules.  Everything I can do here I can also do in ST, but there are some additional restrictions in ST around tires in that I must run 140+treadwear tires as opposed to just DOT stamped tires in Stock.

Cars running in Stock Category must have been series produced with
normal road touring equipment capable of being licensed for normal
road use in the United States, and normally sold and delivered through
the manufacturer’s retail sales outlets in the United States. Car models
not specifi cally listed in any Stock Category class must have been pro-
duced, and must meet the above requirements and been sold through
normal U.S. dealerships, in quantities of at least 1,000 in a 12-month
period in order to be eligible for the Stock Category. A Canadian-market
vehicle is eligible for Stock category if it is identical to the US-market
counterpart except for comfort and convenience modifi cations as al-
lowed per 13.2.A.
A car will remain eligible for Divisional, National Tour, and National
Championship events through the end of the 30th calendar year after
the manufacturer-designated model year of the car. This eligibility limi-
tation applies only to the Stock classes.
Except for modifi cations authorized below, Stock Category cars must
be run as specifi ed by the factory with only standard equipment as de-
fi ned by these Rules. This requirement refers not just to individual parts,
but to combinations thereof which would have been ordered together
on a specifi c car. Any other modifi cations or equipment will place the car
in Street Touring, Street Prepared, Street Modifi ed, Prepared or Modi-
fi ed Categories as appropriate. Confi gurations involving damaged parts
(e.g., blown fuses) are not typically authorized by the manufacturer and
hence are not allowed.
Option package conversions may be performed between specifi c ve-
hicles of a particular make and model, but only between confi gurations
from within a particular model year. Such conversions must be totally
complete and the resultant car must meet all requirements of this Sec-
tion. These requirements are not met by simply pulling a fuse to disable
a feature which distinguishes one model from another.
Alternate parts listed in a factory parts manual are not authorized un-
less their use is specifi cally referenced in the factory service manual or
in a service bulletin for the specifi c model.
See Sections 3.8 and 8.3.1 for documentation requirements.
Alternate components which are normally expendable and considered
replacement parts (e.g., engine and wheel bearings, seals, gaskets,
fi lters, belts, bolts, bulbs, batteries, brake rotors, clutch discs, pressure
plates, suspension bushings, drivetrain mounts, etc.) may be used pro-
vided they are essentially identical to the standard parts (e.g. have the
same type, size, hardness, weight, material etc.), are used in the same
location, and provide no performance benefi t. The allowance for use of
such replacements does not include camshafts, differential covers, or
ring-and-pinion sets, nor does it authorize the use of piston rings having
different confi gurations (e.g. “Total Seal”) from those of the original.
Hardware items (nuts, bolts, etc.) may be replaced by similar items of
unrestricted origin. Safety wire, threadlocker compounds, and locking
nuts are permitted. These allowances are strictly to allow components
to be replaced from alternate sources other than the original manufac-
turer. They should not be construed as an allowance to replace com-
ponents with those which could be considered a ”higher performance”
alternative. Parts available as replacements through the dealers parts
department, the factory, or any other source which do not meet stan-
dard part specifi cations (e.g., hardness, size, etc.) are not legal in Stock
Category, except as specifi cally provided elsewhere in these rules.
Cars listed as eligible in and prepared to the current national Showroom
Stock Club Racing rules are permitted to compete in their respective
Solo Stock Classes. This does not include Showroom Stock cars with
installations of post-factory “performance packages” otherwise known
as “trunk kits.” Neither Showroom Stock nor Solo Stock cars are per-
mitted to interchange preparation rules. Showroom Stock cars may use
tires which are eligible under current SS rules, even if they are not eli-
gible in Stock.
Specifi c vehicle classifi cations are located in Appendix A of these
If a modifi cation is not specifi cally authorized in this or previous sections
of these Rules, it is not allowed.
The addition of small holes for attachment hardware for authorized
modifi cations is implicit (e.g., holes for fasteners to mount additional
gauges, holes for brackets to mount shock absorber remote reservoirs,
etc.). However, these holes may serve no other purpose.
All repairs must comply with factory-authorized methods and proce-
It is not permitted to use illegal parts even if they have been set to Stock
specifi cations.
Refer to Appendix F for past clarifi cations of these rules.
A. Accessories, gauges, indicators, lights and other appearance, com-
fort and convenience modifi cations which have no effect on perfor-
mance and/or handling and do not materially reduce the weight of
the car are permitted. This does not allow driver’s seat substitutions,
or the removal of “tow hooks”, a.k.a. “tie-down loops”. Delayed shut-
down devices such as the “Turbo Timer”, which perform no function
while the car is in motion, are permitted. This does permit the instal-
lation of an additional mirror (e.g. a “Wink”), but does not allow the
removal of the original mirror. “Grounding kits” specifi cally designed
to support sound systems are permitted but may serve no other pur-
B. Data acquisition systems (including video cameras) and the accom-
panying sensors are allowed but may serve no purpose during the
run other than real-time display and data recording.
C. Hood straps or fasteners may be added.
D. Any fuel tank cap may be used.
E. Windshields may be folded (but not removed) provided the required
mechanism is standard equipment.
F. Alternate steering wheels are allowed, provided the outside diameter
is not changed by more than one inch from the standard size. Steer-
ing wheels with an integral airbag may not be changed.
G. Spare tires, tools and jacks may be removed. Any fastening hard-
ware and/or other pieces that can no longer be fi rmly secured in the
absence of the spare tire may be removed if necessary to ensure
compliance with 3.3.3.B.1.
H. Roll bars and roll cages may be added (See Appendix C). This allow-
ance does not permit the removal of standard roll hoops. It is strongly
recommended that roll cages be constructed according to the GCR,
though they must be bolted (not welded) into the automobile and be
contained within the driver/passenger compartment. Roll bars may
be welded in. A roll cage has more than four attachment points to the
body or frame, or has bracing both fore and aft of the main hoop.
I. Driver restraints as outlined in Section 3.3.1 are allowed. Seats may
not be cut to allow for the installation of alternate seat belts or har-
nesses. Passive restraint systems may not be removed. A horizontal
“harness bar” may be used as part of the installation hardware for al-
lowed driver restraints provided it has no more than two attachment
points and is bolted at those locations. A ‘C’-type harness bar may
also be used. It may have four bolted attachment points (two primary,
and two supporting connections to resist rotation).
J. Cars may add one rear trailer hitch. The resulting weight addition is
allowed. The hitch may serve no other purpose. Factory tie downs
and cosmetic pieces (e.g. diffusers) may be modifi ed or removed to
facilitate hitch installation. Complete or partial removal of the hitch is
allowed for competition, provided it does not result in a reduction in
weight compared to the unmodifi ed standard confi guration.
K. Tow bar brackets may be installed but may serve no other purpose.
L. Any item that cannot be held permanently in place by factory-installed
fasteners may be removed.
13.3 TIRES
Any tire which is OE on a car eligible for Stock Category may be used.
Non-OE tires must meet the following requirements to be eligible for
use in Stock category:
A. The tire must not appear on the following list, which may be altered
at any time by the SEB upon notifi cation of membership.
No tire models are currently listed.
B. No tire models will be approved for competition during the rest of
the year after April 30 of each calendar year. Each eligible tire model
must meet all requirements of Section 13.3 by April 30, and must
continue to meet them thereafter. A tire model will normally be deter-
mined by the designation in the Tire Guide.
However, any of the following changes or similar changes (as deter-
mined by the SEB) will also be considered to represent a new mod-
el for eligibility purposes, even if the designation does not change:
change of tread pattern at either full or partial tread depth; charac-
terization by the manufacturer or distributor of a tire as “new” after
April 30.
A tire model which was previously allowed by these rules continues
to be legal until specifi cally disallowed. This follows years of prece-
dence on eligibility for discontinued tire models.
If a manufacturer reintroduces a tire model which was previously
discontinued, that tire will be considered a new model. Therefore,
it will have to meet the rules specifi ed in Section 13.3 including the
April 30 introduction date.
C. The model of tire must be listed in a current or previous two years of
the “Tire Guide” and “Tread Design Guide” or otherwise be approved
by the SEB. The tire model must have Department of Transportation
(DOT) approval.
D. Within each tire model, the sizes which are available must be equally
available to all competitors. Tire model variations differing from stan-
dard specifi cation, delivered only on a limited basis, or only to se-
lected competitors, may not be used.
E. No racing tire or recap (on any casing) may be used. Siping or re-
grooving of tires is not permitted.
F. Each tire model must be sold in at least four rim diameters with a total
of at least six sizes.
G. Tire must fi t the allowable wheels and fender wells without modifi ca-
H. Each tire must have non-zero measurable tread depth (i.e., points
where it is possible to obtain positive measurement values) as de-
scribed in Section 3.3.3.B. Tires may not have cord visible at any
time during competition.
Any type wheel may be used provided it complies with the following: it
is the same width and diameter as standard, and as installed (includ-
ing wheel spacers if applicable) it does not have an offset more than
+/- 0.25 inch from a standard wheel for the car. The resultant change in
track dimensions is allowed.
Wheel spacers are permitted, provided the resultant combination com-
plies with the offset requirements of this section. Wheel studs, lug nuts,
and/or bolt length may be changed.
Vehicles equipped with rims having metric specifi cations may use alter-
nate rims as determined by using the following procedure:
Diameter: converting the metric measurement to inches and using
the nearest smaller inch diameter rim.
Width: converting the metric measurement to inches and using the
nearest smaller 1/2-inch width rim. Offset and track must still com-
ply with the requirements of this section.
A. The make of shock absorbers, struts, and strut housings may be
substituted providing that the number, type (e.g., tube, lever, etc.),
system of attachment and attachment points are not altered, except
as noted below. The interchange of gas and hydraulic shocks ab-
sorbers is permitted. The following restrictions apply:
1. No more than two separate external shock damping adjustment
controls are allowed. This permits the use of shocks which origi-
nally came with more than two external adjustments, which have
been converted to double-adjustables, only if the additional ad-
justment controls have been permanently disabled (e.g. via weld-
ing, epoxying, grinding off). Gas pressure adjustment is not con-
sidered a damping adjustment.
2. Suspension geometry and alignment capability, not including ride
height, may not be altered by the substitution of alternate shock
absorbers. Aftermarket strut housings are allowed provided that
they meet the Stock category shock requirements defi ned herein,
i.e. that no suspension geometry changes result. This includes the
position of the steering arm attachment point in the case of struts
with integrated steering arms.
3. Adjustable spring perches are allowed, but the spring loadbearing
surface must be in the same location relative to the shock mount-
ing points as on the standard part. Shims may be used to achieve
4. The fully extended length must be within plus or minus one inch of
the dimension of the standard part.
5. Electronically controlled shocks may not be used on vehicles not
originally equipped with such units. Vehicles originally equipped
with electronically controlled shocks may use the standard parts
or non-electronically controlled alternative shocks subject to all
the requirements of 13.5. Non-standard electronically-controlled
shocks are not allowed.
B. The mounting hardware shall be of the original type. The use of
any shock absorber bushing material, including metal, is permitted.
Pressed or bonded bushings may be removed from standard parts
to facilitate the use of alternate bushings which fi t in the original loca-
tion without alterations to the part. This does not permit the use of
an offset shock bushing. A shock absorber bushing may be imple-
mented as a spherical bearing. The bushing attaching the end of a
strut to the body or frame on a strut type suspension is a suspension
bushing, not a shock bushing.
For cars with a bayonet/shaft-type upper shock mount, this allowance
permits the removal of the shock bushing from the upper mounting
plate (e.g. via drilling, cutting, burning out the bushing) and replacing
it with another bushing. This also includes shock bushings located in
control arms, etc. This does not allow other modifi cations to the plate
itself or use of an alternate plate.
C. To facilitate the installation of commonly available aftermarket shock
absorbers, struts, or strut inserts whose shaft size is larger than the
center hole of an upper shock mount assembly, that hole may be en-
larged by the minimum necessary to accommodate the shock shaft
size, provided the following restrictions are met:
(1) the enlarged hole must remain concentric with the original con-
fi guration;
(2) the enlargement of the hole does not require modifi cation of a
bearing (as opposed to a washer, sleeve, or plate);
(3) neither the hole enlargement nor the location of the shock shaft
changes any alignment parameter. Provided these constraints are
met, this permits enlarging of the center hole in an upper shock
mount with an integrated rubber bushing, where the bushing is
integral to the mount and bonded to the plate and the mount is
provided by the OEM as an assembly. This includes drilling out
and/or removal of the metal sleeve.
D. A suspension bump stop is considered to be performing the function
of a spring. Therefore, the compressed length of the shock at the
initial point of contact with the bump stop may not be increased from
the standard part, although the bump stop may be shortened for the
purpose of installing non-standard shocks. Bump stops installed ex-
ternally and concentric with the shaft of a shock may be drilled out to
fi t a larger diameter shock shaft. Bump stops may be substituted for
the purposes of installing non-standard shocks.
E. A hole may be added through the bodywork to route the reservoir
and hose to a remote mounting location. Such holes may serve no
other purpose.
F. A hole may be added to an interior body panel to provide access
to the adjustment mechanism on an allowed adjustable shock ab-
sorber. The hole may serve no other purpose, and may not be added
through either the exterior bodywork or a strut bar. Interior panels
are defi ned to be those pieces which cover the interior of the vehicle
(including the trunk area) and are accessible from inside the vehicle.
They do not include structural panels, such as wheel wells or inner
fenders, which may also be accessible from inside the car but which
actually form part of the body of the vehicle.
A. The make and material of brake linings may be changed.
B. Substitution of clutch and brake hydraulic lines with solid metal or
braided metal is allowed on all cars manufactured before model year
C. Alternate brake bleeder fi ttings, such as “Speedbleeders,” are per-
mitted. They may serve no other purpose.
A. For front anti-roll bars:
1. Substitution, addition, or removal of any front anti-roll bar(s) and
supporting hardware (brackets, endlinks, bushings, etc.) is permit-
2. Substitution, addition, or removal of anti-roll bars may serve no
other purpose than that of an anti-roll bar.
3. The use of any bushing material is permitted.
4. No modifi cation to the body, frame, or other components to ac-
commodate anti-roll bar addition or substitution is allowed except
for the drilling of holes for mounting bolts. Non-standard lateral
members which connect between the brackets for the bar are not
B. Rear anti-roll bars may not be removed, replaced, or modifi ed in any
A. Standard, as defi ned herein, suspension springs must be used. They
may not be cut, shortened, or collapsed. Cars with swing axle sus-
pension may be lowered suffi ciently to achieve no more than two
degrees of negative camber at rest and may use a camber compen-
sator. Spring perches may not vary from the OE shape within the
working part of the perch.
B. Both the front and rear suspension may be adjusted through their
designed range of adjustment by use of factory adjustment arrange-
ments or by taking advantage of inherent manufacturing tolerances.
This encompasses both alignment and ride height parameters if such
adjustments are provided by the stock components and specifi ed by
the factory as normal methods of adjustment. However, no suspen-
sion part may be modifi ed for the purpose of adjustment unless such
modifi cation is specifi cally authorized by the factory shop manual for
non-competition purposes.
C. Suspension bushings, including but not limited to those which carry
the weight of the vehicle and determine ride height, may not be re-
placed with bushings of a different material or dimension.
D. Replacement control arms for vehicles having integral bushing/arm
assemblies must be standard factory parts as per Sections 12.4 and
E. If authorized by the manufacturer, the use of shims, special bolts,
removal of material to enlarge mounting holes, and similar meth-
ods are allowed and the resulting alignment settings are permitted
even if outside the normal specifi cation or range of specifi cations
recommended by the manufacturer. If enlarging mounting holes is
specifi cally authorized but no material removal limits are specifi ed,
material removal is restricted to the amount necessary to achieve the
maximum factory alignment specifi cation.
A. The make of spark plugs, points, ignition coil and high tension wires
is unrestricted including spark plug wires having an in-line capacitor.
(Modifi cation of the distributor cap for the purpose of installing al-
lowed non-standard components is not permitted.)
B. On cars made prior to January 1, 1968, any ignition system using a
standard distributor without modifi cation may be used.
C. Ignition settings may not be adjusted outside factory specifi cations.
D. No changes are permitted to electronic engine management sys-
tems or their programming.
E. Additional battery hold-down hardware may be added to supplement
the standard equipment in order to meet 3.3.3.B.15. It may serve no
other purpose.
A. The engine air fi lter element may be removed or replaced. A replace-
ment element, which is taller than standard, may not be used to hold
the air cleaner cover open. No other components of the air induction
system may be removed, replaced, or modifi ed.
B. Engines may be rebored to the manufacturer’s fi rst standard over-
bore, not to exceed 0.020”. Sleeving is allowed to repair to the stan-
dard bore. Only OE-type standard or fi rst overbore pistons of the
same confi guration and of the same or greater weights are permit-
ted. No interchange between cast and forged pistons is allowed.
C. Rotating and reciprocating parts may not be balanced.
D. Port matching is not allowed.
E. Any part of the exhaust system beyond (downstream from) the head-
er/manifold or catalytic converter, if so equipped, may be substituted
or removed provided the system meets the requirements of 3.5 and
3.3.3.B.15. Stainless steel heat exchangers are permitted only if the
physical dimensions and confi guration remain unchanged.
Modifi cations of any type, including additions to or removal of, the
catalytic converters, thermal reactors, or any other pollution control
devices in the exhaust system are not allowed and the system must
be operable. Replacement catalytic converters must be OE if the
vehicle has not exceeded the warranty period as mandated by the
EPA. Converters must be of the same type and size and used in the
same location as the original equipment converter(s). This does not
allow for a high performance unit. If the vehicle has exceeded the
warranty period, replacement catalytic converters must be OE-type
as per Section 13.0.
Exhaust hangers which are bolted or welded on the car are consid-
ered part of the body and may not be changed or removed.
F. Any oil fi lter may be added if not originally equipped. Canister-type
oil fi lters may be replaced with a spin-on type fi lter using a minimum
amount of hardware and connecting lines.
G. The installation of water expansion tanks is allowed. The installation
of oil catch tanks is allowed provided the PCV system is not altered.
H. A scattershield may be added. This does not permit bell housing
I. Thermostats may be added or substituted. A thermostat is a device
which controls the passage of water.
J. Silicone replacement hoses are permitted as alternate components
provided they meet the requirements of Section 13.0 with regard to
size, shape, location, and performance equivalence. Replacement
induction system air intake hoses must also match the standard part
in stiffness, contour, and internal wall texture.
K. A device for locking out reverse gear may be used.
L. Limited-slip differential, transmission and differential ratios, clutch
mechanisms and carburetion, fuel injection or supercharger induc-
tion systems must be standard as herein defi ned.
M. Any oil or grease, including synthetic, is permitted.
N. Valve seats and guides in older engines originally designed for lead-
ed fuel may be only substituted with alternate components if the di-
mensions are the same as those of the standard components.
O. Electronic traction and/or stability control systems may be turned off
or disabled, as long as this does not require connection to an exter-
nal system, removal of any part, or the substitution or modifi cation
of any part.