Afton Motorsports Park Modified and Sportsman Class Rules

The Modified and Sportsman class rules for Afton Motorsports Park are listed on this page.

Forms: [Driver Sponsor Sheet]


Page 1 of Rules: [Seat and Seat Belts] [Driver's Equipment] [Fuel] [Ancillaries]

Page 2 of Rules: [Go to Page 2] Includes Body, Body Style and Dimensions, Body Materials, Roof, Front Door Posts, Rear Wing Windows (Dirt Style Bodies), Body Width and Ground Clearance, Door Panels, Rear Quarter Panels, Rear Spoiler, Rear Deck

Page 3 of Rules: [Go to Page 3] Includes Hood, Nose and Front Spoiler, Hood Scoop, Interior Sheet Metal, Numbers, Driver Name, Sail Panel, Frame, Seat, Radiator, Engine, Transmission, Driveline, Rear End

Page 4 of Rules: [Go to Page 4] Includes Front End, Wheelbase and Tread, Suspension, Springs, Shocks, Brakes, Front Bumper, Rear Bumper, Rub Rails, Mufflers and Exhaust System, Ballast Weight, Battery, Wheels, Tires, Minimum Weights

[PDF of Modified and Sportsman Rules] [Download Adobe Acrobat]


  1. Only round steel roll over bars may be used. Front and rear roll bars must be connected at top in a cage type configuration. Two round horizontal side bars on each side are mandatory. The topside bar must be a maximum of 20" below the top roll bar. Proper bracing and triangulation on front and rear roll bars is required. All roll bar bracing must be a minimum of 1-1/2" diameter by .095" wall thickness. A minimum of one diagonal bar across the top of the roll cage is mandatory.
  2. The rear main roll bar hoop must be a minimum of 26" measured across from outside to outside of tubing and must maintain that measurement from the bottom all the way to the top of the cage. Bottom of the rear roll bar must be directly welded to the 2 x 4 frame (no outriggers). The front roll bar must be measured and constructed the same way, except that the allowable taper in the frame rules will govern the width dimension.
  3. Only two roll bar diameters will be permitted. Roll bars of 1 3/4" diameter will require a minimum of .095" wall thickness. Roll bars of 1-1/2" diameter will require .120" wall thickness.
  4. The roll cage must be integral with the frame. All frames built in 2005 and later must have a manufactures serial number plate prominently attached by welding on the left side front roll cage upright. The letters and or numbers shall not exceed 8 digits and be ½" in height.
  5. A minimum clearance of 1-1/2" is required between the top of the normally seated driver's helmet and the underside of the horizontal roll cage bars.
  6. Shock resistant roll bar padding must fully cover all bars that may come in contact with the driver's head while strapped in the seat. On center type steering, all housings, lines, and fittings must be covered with shock resistant roll bar padding. The steering wheel center must also be padded. The starter housing and any other points of contact that could potentially injure the driver must also be adequately padded. It is recommended that this padding is flame retardant.
  7. All cars must have a functional padded head rest which must be in line with center of driver's head, if not built into the seat.
  8. Adequate window openings on both sides of the car must be maintained for emergency exit of the driver. The minimum opening size is that which will allow a rectangular box with dimensions of 12" high by 18" wide by 30" long to be passed through the inside of the car from one window through to the other side. Any obstacles other than the driver's head rest, which prohibit the passage of the inspection box through the cockpit, must be removed.
  9. All cars must have a drive shaft cover. All cars with open drive shafts, must have a tunnel, made from a minimum of 1/8" thick steel which extends from 2" under front edge of seat to the back of the transmission covering the shaft and "U" joint, and output flange on top and both sides. It must extend completely down to floorboards. It must be held in place with a minimum of four 3/8" diameter bolts at bottom connected to a substantial cross-member. This drive shaft cover must be a solid unit with no cut-aways for lightening purposes.
  10. Two steel safety rings diameter to suite x 1/4" wall thickness x 2" wide, each fastened by two 3/8" grade 5 bolts to the torque arm side plates or the frame must be installed around each universal joint.
  11. Closed drive type cars, torque tubes, or bells that already have a 360 degree covering from "U" joint back to seat will be accepted as is. To protect the driver, any suspension link such as a torque arm, coil over or trailer bar inside the driver's compartment must have a steel cable (1/4" in diameter or more) or clamp connecting it to a substantial cross-member to limit its range should it break loose. These parts must have no sharp edges and must be padded.
  12. Firewalls, both front and rear are mandatory. The rear firewall must extend from the top of the fuel cell to the belly pan to isolate the driver from the fuel cell. A minimum thickness of .050" aluminum or steel is required. A minimal amount of sheet metal may be cut out for drive shaft clearance. The front firewall must fully isolate the driver from the engine compartment.
  13. Belly pans are mandatory and must extend from front firewall to rear firewall and be attached at both spots. It is mandatory to have a separate floor to protect the driver's feet in the event the under pan falls off. This extra floor must be attached to the frame or cross-member or both, and extend from the front firewall past the front edge of the seat.

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  1. All cars must be equipped with 5 point seat belts to SFI 16.1 specifications. All belts must be securely fastened to the frame or cage. Bolts may not be inserted through webbing for mounting. Seat belt webbing that comes into contact with any sharp or un-radiused metal edge must be protected from that edge by means of push on grip vinyl trim. The areas of concern are the webbing slots in the metal racing seats All the seat manufacturers either roll the edge or supply the seat with trim protecting the webbing from abrasion or cutting under impact conditions. Webbing entry slots into the seat with an existing metal roll of 1/8 inch smooth radius will not require vinyl trim.
  2. The areas where the webbing slot has been enlarged by filing or cutting are of particular concern. In most instances the edges have been left sharp, increasing the incidence of belt failure. As racing seat belts are subjected to severe conditions, it is required that worn/frayed belts are replaced immediately, We encouraged that undamaged belts are replaced every 36 months. The date sewn into the webbing should be used as a guide. Belts older than five (5) years old will not be permitted for the 2011 season. Damaged belts will absolutely not be permitted.
  3. Driver's seat must be securely fastened to frame or cage in six spots, with a minimum of six 3/8" bolts, four on bottom and two on the seat back. All seats must have a minimum 1/8" steel plate under and up the back 4" and be as wide as seat. The seat must be one piece high back type only. The seat must be made of aluminum only (no fiberglass). A full containment seat or aftermarket bolt on head restraint is highly recommended.


  1. All drivers must wear a SA 2005 or newer SNELL approved full-face helmet.
  2. All drivers must wear a clean one or two piece SFI driver's suit, quilted or with underwear, head socks, gloves, foot socks and shoes.
  3. Arm restraints are highly recommended. Neck braces are mandatory.

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  1. All crews must carry an operable fire extinguisher of 20 pound marked with the car number in 2 inch numbers/letters in the rear of their transporter, capable of extinguishing gas and oil fires!
  2. On board "flame-out" systems fitted in the race car are recommended.
  3. A fuel cell with a maximum capacity of 24.5 U.S. gallons is mandatory. No pressure tanks are permitted on fuel systems.
  4. The fuel cell must be fully encased in a steel container with a minimum thickness of 20 gauge. An optional aluminum container may be used with a minimum thickness of .060". The cell must be fully foamed with just a minimal cut-out for filler. Cut-out may be no larger than 6" wide by 10" long by 7" deep. Fuel lines must siphon from the top only. There must be a one-way safety valve in the vent line. Fuel tank must be mounted behind driver. Fuel tank must be secured by at least two steel straps (each strap must be a minimum of 1" wide) and bolted with at least (2) 5/16" diameter grade five bolts.
  5. Fuel cells should be to SFI 28.1/.2 or FT3. No fuel cell bladders may be older than 5 yrs from date of manufacture.
  6. A horizontal bar with minimum dimensions of 1" by .095" wall thickness must be mounted behind the fuel cell for rear impact protection.
  7. No racing fuel in drums may be brought on to track premises.
  8. A fuel shut-off valve must be mounted within easy reach of the driver and the safety crew. It must be labeled in a clearly visible location with words FUEL ON /OFF with a bright colored paint or decal.
  9. A minimum of two throttle return springs and a steel toe loop on gas pedal are required. Throttle return springs must be mounted in two different locations.
  10. Fuel tank height: 12" minimum from the ground to the bottom of the tank.
  11. Tank must be centered inside of the frame rails, be rectangular or square in shape on all sides for measuring capacity. The capacity will be measured as a maximum of 5660 cu. in. using the formula with all sizes of the metal container measured externally in inches. Length minus ½" x width minus ½" x depth minus ½" = no greater than 5660 cu. in.
  12. Tank panels may not be bowed out or bellied to increase capacity. No tolerance.
  13. Tanks or lines may not be altered in any way to increase capacity. No large or long fuel lines, no oversize filter housings or fuel coolers.
  14. No fuel lines larger than #10 permitted. No auxiliary tanks, no fuel filters with more than ½ quart capacity.
  15. Fuel tank vent line must have an inline one-way valve to prevent spillage.
  16. Only one carburetor fuel log will be permitted and is limited to a maximum 1" O.D. dia.


  1. All cars must have an ignition switch, which is easily accessible within the driver's compartment. The ignition switch must be marked ON/OFF with a bright colored paint or decal and be clearly visible and easily accessible to the safety crew.
  2. Fuel lines, power steering lines, and fittings running through the driver's compartment must be made from an approved braided type line only. No plastic or glass fuel filters permitted. High pressure lines and fittings or hot fluid lines running through the driver's compartment must be encased or shielded by a deflector to prevent driver injury.
  3. All cars must at all times have four wheel hydraulic brakes in good working order. Brake tests may be held throughout the year.
  4. Rear wheels must have a minimum of five lug nuts. A minimum of three lug nuts is required on front wheels only. No knock off hubs are permitted on any wheel.
  5. Exhaust headers must be safe for the driver and exit past the driver's seat.
  6. All exhaust pipes must exit facing the rear of the car and be directed in such a way as to disturb as little dust as possible. Pipes may not exit through the doors or in front of the rear tires.

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