1. SAFETY EQUIPMENT: Rules apply at all times car is on track. Snell-rated SA2000 or SA2005 helmet required. Roll bar padding required in driver compartment (Fire retardant recommended). SFI-approved full fire suit required. Fire retardant neck brace, gloves and shoes required. Recommended: Fire retardant head sock and underwear; head and neck restraints; collapsible steering shaft. Driver-side window net required, minimum 16 inch by 20 inch ribbon or mesh style, and must be mounted so latch is at top front of window. Minimum three inch wide SFI-approved five point safety belt assembly required (Y-type shoulder harness not allowed), must be mounted securely to roll cage, and recommended to be no more than one year old. Kill switch required within easy reach of driver and must be clearly marked ‘OFF’ and ‘ON’. All weights require 2 (two) ½ inch bolts. No one weight over 55 lbs. Recommended weights be double nutted or safety wired.
2. FRAME: 1964 or newer OEM perimeter American rear-wheel drive passenger car frame only. Camaro OK. No sports car frames. Frame must be full and complete, cannot be widened or narrowed, and must be able to support roll cage on both sides, exceptions are: weight jack in original center line of spring tower allowed; must have stock front clip. Frame may be cut a maximum 36 inches forward from center of rear end housing. If Camaro front clip is used, frame may have 24” removed from rear of clip. Horns may be removed in front of steering box; front crossmember may be notched and boxed for radiator and/or steering clearance; maximum seven inch wide opening in side of spring tower for spring removal. Maximum two inch wide by four inch tall frame stiffener may be welded directly to outside of left side frame rail. Minimum wheelbase is 105 inches, maximum 112 inches, on both sides. Maximum overall width shall not exceed 84 inches from outside of tire to outside of tire. No part of frame can be lower than four inches from ground except front crossmember. Fabricated chassis components recommended .083 thickness 1.75 tube or 2” square minimum.
3. ROLL CAGE: Must consist of continuous hoops, minimum 1.75 inch O.D. tubing, with minimum wall thickness of 0.095 inch for main cage, frame-mounted in at least six places, low carbon or mild steel recommended. Must consist of a configuration of front, rear and top hoops connected by tubing on sides or side hoops. Driver’s head must not protrude outside cage with helmet on. Helmet must have 2” clearance to cage. Roll cage must be securely supported and braced with minimum one cross bar in top halo. Foot protection bar required. Main cage no further forward than rear of engine. All bars forward of cage must be lower than hood. Cage requirements may be waived with prior track approval.
4. DOOR BARS: All driver side door bars and uprights must be minimum 1.5 inch O.D. with 0.083 inch wall thickness. Minimum three driver side door bars, parallel to ground and perpendicular to driver, and welded to front and rear of roll cage. Passenger side must have at least one cross door bar, horizontal or angled, minimum 1.25 inch O.D. with 0.083 inch wall thickness, and one top door bar, minimum 1.5 inch O.D. with 0.083 inch wall thickness. Steel door plate, 18 gauge or 0.049 inch minimum thickness, must be securely welded to outside of driver side door bars and cover area from top door bar to bottom door bar and from rear hoop down-post to five inches in front of seat. Must be visible for inspection.
5. BODY No composite body panels allowed except roof, roof rock guard and hood scoop. No fins or lips anywhere along length of car. Must have stock-appearing nose piece (molded, flexible type material) mounted flat to top of fenders. Roof must be stock appearing, rounded down in all directions. Maximum 1.5 inch rolled down rock guard allowed on roof front. Roof supports and window side panels must extend to within 3 inches of the edge of body. No covers or inner panels allowed. No rear filler panel required. All upper and side panels must run parallel to the chassis. No part of body or nose lower than 3” from ground.
A. Maximum body width at any point is 82 inches except front fender flare which may extend beyond front wheels by 3 inches when wheels are pointed straight. Minimum body width at any point back of nose piece is 76 inches
B. Nosepiece can extend a maximum of 52 inches from center of front hub to furthest point extending forward.
C. Quarter panel can extend a maximum of 52 inches from center of rear hub to furthest point extending rearward.
D. Roof must have roof supports and posts.
E. Front window post 2.5 inches maximum per side including all bends.
F. If roof has openings or quarter windows both must be either open or both sealed.
G. Front and rear of roof must roll, not create a spoiler effect.
H. Roof height must be between 45 and 56 inches from the ground. Roof length and width must both be a minimum of 42 inches and maximum of 56 inches.
I. Roof supports max length is 48 inches and must taper to 0 inches in height at back of support with 3 inches max deviation at center of taper. 18 inch max from rear of roof to front of support.
J. Top of doors and front fenders may not exceed 38 inches from the ground. Minimum 21” tall door. Top of deck measured at rear of car not to exceed 41 inches from the ground.
K. Front fender flares may not be higher than 2 inches from the fenders.
L. Minimum ground clearance is four inches.
M. Rear spoiler may be maximum 12 inches in material height and no wider than the back of body. Spoiler must be made of clear lexan. Spoiler may be made of metal if no more than 4 inches in material height. No stickers, graphics, or paint if over 4 inches. No tinted lexan. Spoiler may be 2 pieces and leading edge may not be mounted above rear deck to form wing.
N. Spoiler may have up to 4 stiffeners. 4 inches max height at front, 8 inches max height at rear and 24 inches max length. Must be in line with car.
O. A single plastic strip may extend below quarter panels. Must conform to ground clearance and overall width rules.
P. No wheel skirts.
Q. No underbody shields.
6. DRIVER COMPARTMENT: Must have minimum three 3/16 inch windshield bars in front of driver. Minimum 0.125 inch aluminum, or 0.060 inch steel, complete floor pan required. Aluminum high-back seat only and must be bolted in, using minimum 0.375-inch bolts, next to left side frame rail and ahead of rear tires. Bottom of seat can be no lower than bottom of frame rail. Driver must be sealed off from track, driveline, engine, fuel cell, canisters and pumps. Oil coolers must not protrude above interior. Accumulators cannot be mounted between driver and left-side door bars. No driver-adjustable devices allowed while car is in competition except brake adjuster. No mirrors of any kind.
7. FRONT SUSPENSION: All components must be steel, unaltered OEM, in OEM location, and replaceable by OEM parts, exceptions are: tube-type upper A-frames with or without aluminum or steel cross shaft, and mounts can be moved; stamped steel OEM replacement lower A-frames; rubber, nylon or steel lower A-frame bushings, no offset or bearing type; welded or bolted shock mount on lower A-frame. Lower A-frames must be right and left, and of same design. Lower A-frame mounts and bolt holes on frame must be in OEM location. OEM ball joints only. Sway bar must be unaltered OEM.
8. STEERING: Rack and pinion OK. All components must be steel, unaltered OEM and may be relocated, exceptions are: outer tie rod end and adjustment sleeve may be replaced by a minimum 0.625 inch steel rod end and steel tube; OEM spindles can be ground for brake caliper clearance only; Fabricated or modified OEM spindles OK. Recommend that spindle modifications be performed by experienced welder/fabricator for safety. Bolt on spindle savers allowed; steel steering shafts and knuckles only; driver compartment steering may be modified, must be kept on left side. Quick release required - steering quickener and steering wheel may be aluminum.
9. SHOCKS: One steel, nonadjustable, unaltered shock per wheel. No bumpers or stops. No threaded body, front coil-over, air, or remote reservoir shocks. No Schrader or bladder type valve allowed. Front half may be shielded. One or all shocks may be claimed for $50 ea.
10. SPRINGS: One steel, non-progressive coil spring per wheel only. Steel or composite leaf spring allowed. Half leaf spring allowed in combination with 1 coil spring per side. Any coil spring must be at least 4.5 inches O.D. No torsion bars, air bags or inner liners.
11. REAR SUSPENSION: All components must be steel. All mounts and brackets must be welded or bolted solid. Steel coil-over eliminators or steel or aluminum coil-over kits allowed - must conform to shock and spring rules. Note; rear shocks, coil springs and coil eliminators may be mounted in any location.
Must utilize one of the following designs:
(A) Aftermarket three link design requirements: Must use minimum 16 inch lower control arms. Must use one upper control arm, solid tube or 1 biscuit or 1 springer bar, located at top center of rear end housing and remain horizontally centered (1-inch tolerance) on housing over drive shaft. Must use minimum 19 inch panhard.
(B) Leaf spring design requirements: Steel or composite leaf spring allowed. May run half springs attached at front mount in combination with one coil spring per side. One shock per wheel. Adjustable aluminum lowering blocks allowed. Rear sliders and adjustable shackles are ok.
(C) OEM stock design requirements: Rear crossmember, control arm mounts and bolt holes on frame must be in stock location. All components must be unaltered, approved OEM, and match frame. Control arms cannot be altered in any way. Steel, rubber or nylon control arm bushings only.
12. REAR END: Any steel approved OEM passenger car or truck rear end (housing and carrier) allowed. Safety hubs (floater) allowed. All components must be steel, except lowering blocks, axle cap, drive flange. Inspection hole required in housing. Full steel spool, steel mini spool or welded rear ends only. Steel axles only. No cambered rear ends. One piece drive flange only. No torque dividing differentials. No scalloped ring gears.
13. BUMPERS: All nerf bars, must be entirely inside of body skins. Rear bumper may not protrude beyond the rear of the spoiler. Must be either looped back to chassis or bumper mount. No sharp edges. All cars must be equipped with tow hook or similar device front and rear.
14. TIRES/WHEELS: 36108 stamped “500” Hoosier Race Tires only. 8 inch wide Hoosier RC-4, IMCA 500, G-60 or AR KK-704 also OK on left front only. No softening, conditioning or grooving. Grinding allowed on tire tread only. Maximum 10 inch wide wheels; bead locks allowed on right side only. External bead lock only, cannot make wheel wider than 10.75 inches. Foam or plastic (must be bolted behind bead lock rim) mud plugs allowed on any wheel. No wide 5 wheels. Wheel spacers permitted.
15. BRAKES: Must be steel OEM, operative four wheel, drum or disc. Must maintain minimum OEM dimensions for hubs/rotors and calipers cannot be lightened. Bolt pattern may be changed. Larger studs allowed. Rear rotors may be aftermarket 0.81 inch thickness. Vented rotors only, no scalloped or ceramic coated rotors. No pressure sensitive devices. One front to rear proportioning device allowed. Brake lines must be visible. Must be operative and lock up all four wheels during any Inspection. No cutoff valves.
16. EXHAUST: Round tube headers only. Muffler or mufflers must be used. All exhaust must go through mufflers. No exhaust sensors.
17. FUEL SYSTEM: Mechanical or belt driven fuel pump only and must be mounted at front of engine. Racing fuel cell required, maximum 32 gallon capacity must be in minimum 20 gauge steel container. Cell must be securely mounted behind rear axle, between rear tires, minimum of four inches ahead of bumper, minimum of ten inches above ground. Must mount with minimum two solid steel straps around entire cell, two inches wide and 0.125 inch thick. All cell mounts must be steel, securely welded to frame/cage. Protective tubing must cover rear and extend past both sides of cell. No part of cell shall be lower than protective tubing. Fuel cell vents, including cap vent, must have check valves. If fuel cell does not have aircraft style positive seal filler neck/cap system - a flapper, spring or ball type filler rollover valve is required. Pick-up must be on top or right side of cell. Limit of one fuel filter. No cool cans. Air cleaner top/stud cannot direct air into carburetor. No top flow air cleaner housings.
18. FUEL: Gasoline or alcohol. Racing fuel allowed. Fuel shut off valve recommended.
19. WEIGHT: Weights must be securely mounted to inside of frame or roll cage and painted white with car number on it. Must be attached with at least two 0.5 inch bolts. No titanium, magnesium or carbon fiber products. Only carbon fiber components allowed are rock guard and hood scoop. No gun-drilled, tubular, hollow bolts or studs. Steel fasteners only.
20. BATTERY/STARTER: One 12 volt battery only, must be securely mounted between frame rails, and positive terminal must be covered. Car must have capability of starting without being pushed or pulled. Car must leave initial staging area on demand, unaided, or go to rear of that race. Reverse-mount starters with OEM case transmissions only, see transmission rules for specifics.
21. GAUGES/ELECTRONICS: No unapproved cameras, transmitting or listening devices, timing retard controls, or digital gauges (including tach). No electronic monitoring computer devices capable of storing or transmitting information except analog tach. No adjustable ignition control boxes. One 12 volt ignition box (MSD type) allowed, must be out of driver’s reach. No additional ignition accessories allowed. Only change allowed to ignition box is one high-end rev-limiter setting. This setting can be changed through one chip only, or an internal setting inside box. No magnetos. No electronic traction control devices. Radios are not legal.
22. TRANSMISSION/DRIVESHAFT: Must have at least two forward gears and one reverse, plus a neutral position. With engine running and car in still position, must be able to engage car in gear and move forward, then backward. OEM production type or IMCA approved aftermarket transmissions allowed - two-speed, three-speed, four-speed and automatic. No five speed (or more) transmissions, ‘in and out’ boxes, or quick change devices allowed. Functioning shift levers must be in OEM location on all OEM production type transmissions. All belt drive pumps must be mounted on front of engine. Flexplates must be full, steel, unaltered OEM, or OEM replacement. Flywheel/flexplate must bolt to engine between clutch assembly and crankshaft and all driveline components within bellhousing must rotate while car is in any gear. Transmission must be one of the following designs:
OEM Manual: Must have a standard OEM case and working disc-type clutch or approved cone or disc-type coupler inside an explosion-proof steel bellhousing. One flywheel only, minimum 8.5 inch diameter. Diameter of clutch disc must be a minimum of 5.5 inches. Clutch assembly must be steel, except housing, which must be steel and/or aluminum. Bellhousing can have only a hole for throwout bearing lever or hose, must be 270 degrees around top of clutch and flywheel area. Standard mount starter only, must directly engage flywheel.
Automatic: Must remain in OEM or OEM replacement case, with a functioning OEM appearing pump. Aluminum OEM bellhousing may be replaced with aftermarket explosion-proof aluminum bellhousing. Original OEM bellhousing must have approved scattershield constructed of minimum 0.125-inch by three-inch steel, 270 degrees around flexplate. Approved racing style blanket OK.
Aftermarket Manual: Must securely add 50 pounds weight to cage or chassis on the right side of, and ahead of, the rear of the transmission tail housing. Weight must be removable and accessible for tech. Must be, aluminum case, with internal clutch. Must bolt to explosion-proof steel bellhousing, and use full, steel, unaltered OEM or OEM replacement flexplate with starter mounted in OEM location.
Drive Shaft: Minimum two inch diameter steel drive shaft and must be painted white. Steel slip-yokes only. 360-degree drive shaft loop required and must be constructed of at least 0.25 inch by two inch steel, or one inch tubing, mounted six inches back from front U-joint.
23. ENGINE COMPARTMENT: Rear of engine (bell housing flange) must be mounted at least 72 inches forward from centerline of rear axle. If 78 inches or less, must add 50 lbs of lead foreword of radiator. Weight must be removable and accessible for tech. Engine offset must be kept within two inches of centerline of front cross member with engine level. Minimum 11 inch engine height from ground to center of crankshaft. Radiator must be mounted in front of engine. Cooling system may be modified. Overflow tubes must be directed to ground between frame rails.
24. ENGINE SPECIFICATIONS: Any American make engine allowed. Steel heads, block and oil pan only. OEM passenger vehicle production block only. No GM Bowtie, Ford SVO or Chrysler W blocks. No mushroom lifters. OEM firing order cannot be changed. No crank triggers or other devices inside driver’s compartment that allow adjustment of timing. All engines must be able to be used in conventional passenger car without alterations. Engine mounts cannot be removed or altered. Castings and fittings must not be changed. No machine work on outside of engine. All belt driven accessories must be on front of engine. ‘Wet’ sump oiling system only. No external oil pumps. Remote oil filter and lines permitted. 1 (One) remote oil filter is allowed. 1 (one) oil cooler is allowed. No magnetos.
25. ENGINE RULES:
A. Block, heads, crankshafts and connecting rods must be steel.
B. Maximum of 413 c.i. allowed.
C. Maximum valve sizes are 2.08 intake and 1.600 exhaust.
D. Camshafts may be flat tappet or roller design.
E. $700 claim on carburetor $200 claim on MSD box $200 claim on distributor assembly.
F. GCS reserves the right to confiscate any and all ignition components at any time and shall supply such racer with another ignition system.
26. CARBURETOR: Any naturally aspirated two- or four-barrel carburetor. Carburetor must have a 1.6875” (1 and 11/16”) base plate maximum or must run one (1) ½ inch tall max, ¼ inch tall minimum restrictor plate with straight bore (non tapered) 1.6875 holes. Billet base plate OK max .780 tall. Max one gasket per surface allowed. Max of .070 per gasket.