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SECTION 10 - MODIFIED DIVISION
GENERAL RULES AND REGULATIONS

10-1. BODIES

A. 1970-or-newer American compact passenger car only - no panel vans or station wagons. Tar racing type bodies with windows are allowed.

B. Firewall is mandatory. Minimum 0.125-in. aluminum, or 16-gauge or 0.060-inch steel, complete floor required. Fiberglass or metal duplicates of body parts are permitted. Handmade body parts may be constructed of steel, aluminum, or fiberglass, but should be recognizable as factory production vehicle. No carbon fiber.
C. All cars in competition must have a complete paint job. No reflective doors or quarter panels. No plastic body parts allowed. Body must be the same width, front to rear, and parallel to the frame.

D. Original roof line of vehicle must be maintained. Must be a full-size roof. No wings. Rear spoiler allowed: 4" tall, top 3" clear plastic, cannot be wider than rear body. Total of 240 sq. in. maximum. Three-inch tall spoilers may be more than 60 inches wide, but not wider than the rear body or over 240 sq. in. Sail panels must closely resemble examples shown on body diagram and be the same on both sides of car. Reinforcing lips on rear of sail panels must be 180-degree bends.

E. Engine compartment will remain open, no side panels. Hood sides may have maximum 4-in. drop and must be enclosed at rear of hood. Maximum hood scoop height: 6 in.  Passenger side of body must be no further forward than rear of block. Rear of bodies to be solid panel at least 8 in.high. No panel in front of right door to engine compartment. No inner panels.

F. Engine must be enclosed from driver, (hot water, oil and fire) full windshield, or back of hood blocked off will be allowed. No open holes between motor and driver.

G. Mirrors are allowed.

10-2. FRAMES

A. Ground clearance: 4 in.  Frame: 3 ½ in.  Oil pan without driver. No part of race car can be lower than 4 in. from the ground (exception is front crossmember and oil pan, the head of the bolt will be allowed). Weight: 2,500 lbs.; 57% left-side weight with driver before race (aluminum heads add 100 lbs, 56% left-side weight).

B. Factory production complete full 1960-or-newer parallel American passenger car frames only. Frames may be cut in rear only at point not further than 36 in. from center of rear end housing. No front clips or tube type allowed. Maximum 2 in. wide by 4 in. tall frame stiffener may be welded directly to outside of frame rail.

C. Frames may not be widened or narrowed and must be able to support roll cage on both sides. Must be full and complete both sides. Front crossmember must remain full and intact. Center of crossmember may be notched and boxed for radiator and/or steering clearance only.

D. No Jeep, Bronco (etc.) or four-wheel-drive frames allowed. No sports car frames allowed. No front-wheel-drive allowed.

E. Minimum wheelbase: 108 in., both sides. Maximum overall width (front or rear) shall not exceed 78 in. from outside of tire to outside of tire. Front tire width will be measured at the top of the tire sidewall with driver in car. (Zero tolerance, i.e. 78 1/16" will not be allowed).

10-3. SUSPENSION AND STEERING

A. Front suspension must be unaltered, approved OEM and be in stock location and must be replaceable with stock parts. Tie rod ends and adjustment sleeve may be replaced by a minimum 0.625-in. rod end and steel tube. (Heim joints allowed.)  Weight jack must be in original center line of spring. Stock passenger car spindles only (no fabricated spindles). Spindles may be ground for brake caliper clearance only. Bottom A-frames cannot be altered or moved (exception: can weld shock mount on A-frame; aftermarket ball joints are allowed). No offset or bearing-type lower control arm bushings. Tube-type upper A-frames allowed and can be moved. Front sway bar can be an aftermarket type. Chain on one side is allowed. Suspension, steering, and rear end parts must be steel. Steering box must be steel, approved OEM, and must remain within original bolt pattern for type of frame used. No rack-and-pinion allowed. Steel steering shafts and knuckles only. In-cockpit steering may be modified to suit driver's taste, but must be kept on left side of cockpit. No center steering allowed.

B. No devices allowed that would enable driver adjustment to alter wheelbase or for weight jacking while car is in competition. No air shocks or air bags allowed.

C. Shocks: only shocks allowed are one steel, non-adjustable, unaltered shock per wheel. No threaded body shocks, front or rear, or air type, or remote reservoir shocks, or "Schrader" valves. No valves of any type. Shocks cannot be mounted in center of spring.

D. Springs: Only springs allowed are one steel, non-progressive coil spring and/or steel leaf spring per wheel. All coil springs must be at least 4.5-in. O.D. No torsion bars or air bags.

E. Rear suspension: no independent rear suspension. All components must be steel. No covers allowed. All trailing arms or link bars must be solid tubing. Rear of frame may be altered to accept leaf or coil springs. Steel coil-over eliminators or steel or aluminum coil-over kits are allowed, but must conform to shock and spring rules. Minimum 19-in. long panhard bar, measured center to center. No cambered rear end housings. One mechanical traction bar, rubber bumpers allowed.

10-4. ENGINES

A. No aluminum blocks or oil pans. No magnetos. Maximum cubic inches: 410.

B. Any American-make engine may be used as long as rear of engine (bell housing flange) is mounted at least 72 in. forward from the center line of rear axle. Engine offset must be kept within 2 in. of centerline of front crossmember with engine level.  Engine height: 11 in. engine height minimum from ground to front center of crankshaft.

C. All engines used in competition must be able to be used in conventional passenger car without alterations. Motor mounts cannot be removed or altered. Castings and fittings must not be changed. No machine work on outside engine.

D. Wet-oiling system only. Oil coolers must not protrude above interior. Accumulators cannot be mounted between driver and left-side door. External one-stage oil pump allowed.

E. Cooling system may be modified. Any overflow tubes must be directed to the ground, between frame rails. Radiators to be mounted in front of engine only.

F. Conventional air cleaner housings only. No top-flow air cleaner housings allowed. K&N performance air filters are allowed.

10-5. ENGINE EXHAUST SYSTEM

Exhaust system must be mounted in such a way as to direct spent gasses away from cockpit of vehicle and away from areas of possible fuel spillage.

10-6. DRIVE TRAIN

A. TRANSMISSION AND DRIVESHAFT: Must have at least one forward gear 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 ASA-approved aftermarket transmissions allowed: two-speed, three-speed, four-speed and automatic. No five-speed 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 bell housing must rotate while car is in any gear.

Transmission must be one of the following designs:

B. 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 bell housing. One flywheel only, minimum 8.5-in. diameter. Diameter of clutch disc must be a minimum of 5.5 in. Clutch assembly must be steel, except housing, which must be steel and/or aluminum. Bell housing may have only a hole for throwout bearing lever or hose must be 270 degrees around top of clutch and flywheel area. Standard or reverse mount starter allowed, must directly engage flywheel.

C. 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 .125-in. by 3-in. steel, 270 degrees around flexplate. Automatic Transmissions are not allowed
D. Aftermarket manual: must be ASA-approved aluminum case with internal clutch. Must bolt to explosion-proof steel bell housing, and use full, steel, unaltered OEM or OEM replacement flexplate with starter mounted in OEM location. No coatings or paint allowed on transmission case.

E. Driveshaft: minimum 2-in. diameter steel drive shaft and must be painted white. Steel slip-yokes only. Driveshaft loop: 360-degree driveshaft loop required and must be constructed of at least .25-in. by 2-in. steel - or 1-in. tubing, mounted 6 in. back from front U-joint.

10-7. REAR END

A. Any approved OEM passenger car type or truck rear end may be used.

B. No aluminum allowed, except lowering blocks, axle cap and drive flange. A 1-in. inspection hole in center section is recommended. Full steel spool, steel mini spool or welded rear ends only. No open or unlocked rear ends. Steel axles only. We will pull rear end out and look for aluminum this season.

C. No quick-change devices allowed. No cambered rear ends.  One-piece drive flange only. No electronic or mechanical traction control devices allowed.

10-8. BRAKES

A. Must have a working caliper and rotor on each wheel and must lock up all four wheels.

B. Brake shut-off or pressure-sensitive devices allowed.

C. One proportioning device allowed, front-to-rear only.

D. Brake lines must be outside frame rails and visible.

E. Vented rotors only, no scalloped rotors. Rotors cannot be lightened. Rotors may be re-drilled for different
bolt pattern or larger studs. Must be steel, approved OEM calipers and they cannot be lightened.

 

10-9. TIRES AND WHEELS

A. Track tire is Hoosier 970. No soaking or altering of tire compound in any way.

B. No wide-five wheel adapters allowed. Aluminum or steel spacers allowed.

C. May use bead lock on right-rear only. Wheel: must be an ASA or IMCA-approved wheel prior to use as a bead lock wheel. External, steel bead lock only and it cannot make the wheel any narrower than 8 in. and no wider than 8.75 in., measured at the outside of wheel bead.  Must use only steel bolts. One foam-type or plastic mud cap allowed on right rear only. Rim-mounted bleeder valves are not allowed.

D. Must qualify and race on the same tires and wheels.

10-10. ELECTRICAL SYSTEM

A. One 12-volt battery only, must be securely mounted and shielded. All vehicles must have the capability of starting without being pushed or pulled. All cars must join lineup on demand, unaided, or go to rear of that race.

B. One 12-volt non-adjustable ignition box and coil allowed. Must be out of driver's reach. No additional ignition accessories allowed. The only change that can be made with ignition box is rev limiter setting and only one high-end setting is allowed. This setting can be changed through one chip or an internal setting inside the box.

C. No electronic or mechanical traction control devices allowed.

10-11. FUEL SYSTEM

A. Racing fuel cells required and must be mounted by at least two solid steel straps, two inches wide around cell.

B. Fuel cells must be enclosed in steel container and must be mounted securely behind rear axle and between the rear tires, no lower than ten inches off the ground, protected by roll-cage tubing.

C. Protective tubing must cover the rear and extend past both sides of fuel cell.

D. Fuel cell must be a minimum of four inches ahead of rear bumper and no part of fuel cell shall be lower than protective tubing.

E. Fuel cell vents, including cap vent, must have check valves, and bladders are highly recommended.

F. Fuel cells are limited to 32-gallon maximum capacity.

G. Pick-up must not be underneath fuel cell.

H. A limit of one standard fuel filter allowed between the fuel cell and carburetor.

10-12. CARBURETOR

A. One two-barrel - or one four-barrel - carburetor allowed. Must be naturally aspirated.

B. No fuel injection. No electric fuel pumps.

10-13. FUEL

A. Must be track-specified fuel and purchased from track.

B. No nitrous oxide. No performance-enhancing fuel additives of any kind.

10-14. CHASSIS AND ROLL CAGES

A. Must consist of continuous hoops not less than 1.666-in. outside diameter with a wall thickness of at least 0.095-in. Low-carbon mild steel tubing is recommended.

B. Must be welded to frame in at least six places. No brazing or soldering allowed.

C. Must consist of a configuration of front and rear hoops connected by tubing on the sides or side hoops.
Driver's head must not protrude outside cage with helmet on and strapped in driver's seat. Must have minimum of one (1) crossbar in top halo of roll cage. Roll cage must be securely supported and braced.

D. Protection of feet is mandatory. Bar across back of engine with vertical bars and rub rails, or similar
protection. No brace bars forward of cage may be higher than stock hood height. Main cage no further forward than engine plate.

E. A minimum of three driver's-side door bars, at least 1.5-in. O.D.  Must be as parallel with the ground as possible and located perpendicular to the driver so as to provide maximum protection for driver, but without causing undue difficulty in getting into or out of vehicle.

F. The side bars must be welded to the front and rear of the roll cage members. Must have at least one cross door bar, minimum 1.25-in. O.D. on passenger side of car, either horizontal or angled.

G. Steel door plates, 18-gauge or 0.049-in. minimum thickness metal, must be securely welded to outside of door bars on driver's side. Plate must cover the area from the top door bar to the bottom door bar and from the rear down post to five inches in front of the seat. Must be visible for inspection.

10-15. SEATS AND SAFETY EQUIPMENT

A. Helmets are required and must be Snell-rated SA90, SA95 or SA2000. Helmet must be worn at all times when car is on the track and must accompany vehicle at time of inspection.

B. Roll bar padding required in driver compartment.

C. Fire-retardant padding recommended.

D. SFI approved full fire suits of a flame retardant nature must be worn by all competitors. Fire retardant neck braces and fire retardant gloves are required, fire retardant shoes highly recommended.

E. Arm restraints and full-size (minimum 16"x20") driver-side window net required (no string-type nets).

F. Five-point safety belts, sub belt, shoulder harness required. The shoulder harness must be mounted securely to the roll cage. Belts and harness recommended not to be more than one year old, and cannot be more than three years old.

G. Aluminum high-back seats only, must be bolted in and mounted inside the frame rail and ahead of the rear tire. Bottom of seat can be no lower than the bottom of the frame rail.

H. Kill switch required within easy reach of driver clearly marked "OFF" and "ON.".

I. A 360-degree drive shaft loop is required and must be constructed of at least ¼-in.-by-2-in. steel or 1-in. tubing, mounted 6 in. back from front U-joint. Steel drive shafts (minimum two-inch diameter) and yokes only. Drive shaft must be painted white.

10-16. BUMPERS

Center of bumper, front and rear, must be 18 inches, plus or minus two inches, from ground.

A. Steel bumpers must be used both front and rear at all times and securely mounted with minimum 0.375-inch bolts. Must be made of minimum 1.25-inch OD tubing, 0.065 wall thickness on front - 0.095 wall thickness on rear, and must be able to support car if lifted by wrecker. Two-bar front bumpers must be mounted frame end-to-frame end, no wider than the width of material outside frame horns, with the bottom loop parallel to the ground. Top bar must be directly above bottom bar, minimum 6.5 inches apart, measured center to center at front of bumper (see P in body diagram), so bumper is perpendicular to ground.

B. Rear bumper, steel nerf bars and bodies must not extend beyond width of tires, and must not contain any sharp edges. Rear bumper no more than two inches wider than body on each side.

C. Rear bumper must resemble one of three configurations, see diagram on page four.

D. Nerf bars: all cars must be equipped with approved side rail bars and scrub rails constructed of .083-in. minimum magnetic steel seamless tubing with an outside minimum diameter of 1.250 in. Only one (1) side rail bar per side will be permitted and it must be full length from front to rear with minimum tire clearance. Side rail bars must be center-lined with the front and rear axles. Only two (2) intermediate supports per bar will be permitted. Side rail bars and scrub rails must be fastened to the frame. Side rail bars and scrub rails must not extend past outside edge of the rear tires and taper slightly toward the front tires. Rear quarter panel side rail bars, right side will be no wider than four (4) inches to the outside of the side rail. Left side will be no wider than the outside of the left rear tire.

10-17. WEIGHTS

A. Minimum weight limit: 2,500 lbs., before the race with driver in the car. Zero tolerance.

B. Loose objects and/or weights must not be used in driver's compartment or outside of the body or hood area. Any weights added to other areas of vehicles must be securely mounted with at least two (2) half-inch bolts, painted white and have the car number on it.

C. No titanium, magnesium or carbon fiber products, parts or components allowed.

D. No gun-drilled, tubular or hollow bolts or studs.

10-18. WINDOWS

A. Stock-appearing front windshield and rear window support unit (a.k.a. "a-pillar" and "c-pillar"). Painted roll bars not acceptable substitute. May utilize a full-windshield, with no wings, mounted to the roll cage. Must have a minimum of three windshield bars in front of driver. Cowl panel in front of driver can be no wider than cockpit and no farther back than the steering wheel.

B. Driver and passenger side windows must have at least 12-in. opening, measured at center of window, between the lowest point at the top of window, whether the roof or roll cage, and the highest point at the bottom of window, whether the interior or body.

C. Window net to be mounted so that latch is at top front of window.

10-19. APPEARANCE AND IDENTIFICATION

A. All cars must be numbered with large legible numbers on both sides, on top and rear panel. Numbers on sides and top of car must be in contrasting color from body, be at least four inches wide and at least 20 inches high. Recommended that no holographic or reflective materials be used.

B. Sponsors' names must not interfere with car numbers and must be neatly lettered.

10-20. COMMUNICATION

A. The use of a two-way radio for communication with a spotter and/or pit crew member is recommended.

10-21. ELECTRONICS

A. Radio (recommended).

B. No electronic monitoring computer devices capable of storing or transmitting information except tachometers.

C. No digital gauges, timing retard controls or oxygen sensors allowed.

D. No electronic traction control devices allowed.

10-22. ENGINE CLAIM

A. None.