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: [Go to Page 1] Includes Seat and Seat Belts, Driver's Equipment, Fuel, Ancillaries

Page 2 of Rules: [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. No mirrors or reflecting devices permitted.
  2. Inspectors reserve the right to request body or sheet metal to be replaced and painted if it has any sharp edges or is not looking presentable to the sport.
  3. No oil cooler may be mounted external to the bodywork. All oil cooler piping shall be routed under the bodywork, as safely away from driver as practical.
  4. Oil coolers may be no further forward than the centerline of the rear axle. The cooler must be horizontal and flush with the cut out in the deck.
  5. Oil coolers with a duct covering them on both sides and the rear may be mounted further forward than the center line of the rear axle.
  6. Oil coolers may be mounted under the hood ahead of the motor.
  7. Maximum rear spoiler height, regardless of ride height, may not exceed 50". This height will be randomly measured during an event. Cars not in compliance will be excluded. It is suggested that manufactures do not make tall cars that can only pass tech at low ride heights. The following race car driver must be able to see through for clear view of track ahead.
  8. All cars must have a full steel windscreen (rock guard) of substantial material with a maximum individual hole opening of 2" by 1" by 1/16" (no chicken wire or aluminum). Screen must cover entire windshield area left to right across the cage and from top of cage down to hood or cowl. Clear lexan or safety glass windshields may be used for additional protection if they are in the driver's line of sight. They must be shatterproof and mounted behind the screen enabling driver to wipe them clean. Any additional windshield must not obstruct the emergency exit of the driver.

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  1. Only aluminum or steel will be permitted for all inner and outer body panels.
  2. A maximum of 4" vertical plastic material extending below the metal body panel is permitted. The plastic thickness shall be between .090'' and .125'' and an overlap of 2" to secure to the doors/door extensions will be permitted. Doors/door extensions must still have a minimum of six inches of ground clearance including plastic material
  3. The overall dimensions of the doors and door extensions must meet the specifications.
  4. The roof must be fiberglass only.
  5. Hood, hood scoop, windshield cowl, right rear inside tire clearance cover and front spoiler may be constructed of either fiberglass or aluminum.
  6. Only CLEAR! lexan will be permitted for the rear spoiler and the rear wing windows. NO STICKERS OR WRITING WILL BE ALLOWED ON THEM!


  1. The roof must be centered from side to side on roll cage and also be centered on frame (No offset bodies). Leading edge of roof must be fastened in a stationary position a minimum of 33" and a maximum of 48" in front of rear axle centerline. The roof must be securely fastened at the back and on both ends.
  2. Length of the roof: maximum 60", minimum 48". Width of roof: maximum 52", minimum 48". It must display a turtleback style and shape with at least 3/4'' belly front to rear and 3/4" side to side. The roof contour must fit roof template patterns left to right and front to back (NO FLAT ROOFS).Front lip may not be more than 1/2''. Side edges may be no longer than 11/8" break.
  3. The roof cannot change shape or location while racing.
  4. Overall height (top of highest point): minimum 52", maximum 61", measured from the ground. Maximum roof angle is 5 degrees.
  5. The roof must be one piece fiberglass only and be a single ply, one contour inside and out. No carbon fiber. Roll bars must be exposed. No vertical metal used to mount roofs will be permitted covering the roll bars. The roof must weigh a minimum of ten pounds.

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  1. Door posts must be flat aluminum sheet metal Only! They must go in a straight direct line from the roof to the doors. From a side view they must be seen as a 2" dimension. They must be no wider than 2". They may be bead rolled or have a lip for re-enforcement, but can't exceed a 3/8" maximum thickness at that area. The material thickness used may be a minimum of .050" to a maximum of .090" inches. Only a one-piece construction will be accepted! There will be no Tolerance on these measurements. Door-posts must attach securely to the metal roof support and doors! They may be bolted with a min. of (2) 3/16" bolts to the door bracket for the ease of fabrication!
  2. No lexan vent windows or excessive sheet metal will be permitted in the vent corner where the post meets the door panel.


  1. All rear wing panels and windows must resemble a current OEM body style. Their upper profile may not protrude above a straight line drawn from the rear of the roof to a point 3'' higher than the rear deck. There must be at least a 2" indent in the profile, so as not to make this panel a fast back.
  2. The maximum base length may not exceed 61''. Left and right must be of the same style and dimension!.
  3. All window styles must be nominally 160 square inches (suggested 10" tall x 16" long), clear, smooth lexan with no bends or breaks.
  4. No writing or decals permitted on the wing windows.
  5. Rear view of the wing window must go in a straight line from top of quarter panel or body line to the roof, with a maximum gradual bow of 2" in the center of wing window.


  1. Body width (measured anywhere along the body line, front or back): 68" maximum, 64" minimum.
  2. Minimum chassis ground clearance 2 1/2".
  3. No fan or ground-effects cars are permitted.
  4. No rubber skirts, fins, or spoilers of any description are permitted under the car.
  5. A 2" max air deflector is permitted in front of radiator to facilitate cooling.

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  1. Side door panel: minimum 60", maximum 70" in front of centerline of the rear axle. Doors, front door extensions and rear quarter panels must be flat and mounted in a vertical position. They must remain flat with no louvers, bead rolls, holes or protrusions from top to bottom. The exception being for rub rails. Doors may have a max. of a 1" long lip at a 45 deg. outward angle 1/2" away from the sheet metal for the purpose of reinforcement. This will be allowed at the top and bottom of the panels. All outside sheet metal, door panels, door extensions, air dams, front nose & hood fins must be the same shape, size, and angle on both sides of the car. Doors must match each other from side for side. (Must be symmetrical)
  2. Bead rolls around the outside perimeter of these panels and the wing windows will be allowed. Bead roll edges must face towards center of chassis.
  3. Front door extensions will be permitted up to 20" behind the front axle centerline.
  4. Front door height must be a maximum of 38" and minimum of 30" from the ground measured at 60" from rear axle centerline.
  5. Ground clearance on the bottom of the doors must be a minimum of 6" and a maximum of 12" from the ground.
  6. All doors and rear quarter panels may have a maximum lip of 1 1/2" rounded at 90 degrees and facing inward only, on the top and the bottom.
  7. At the top of the doors and rear quarter panels, a lip angled out at a maximum of 45 deg., protruding away from the door no more than 1/2" and no more than 1" in length before it bends inward for strength will be permitted.


  1. Rear quarter panels must match each other. (Must be symmetrical)
  2. Quarter panels must be a maximum of 47" and a minimum of 40" from the ground at the rear and continue in a straight line with top of door.
  3. A fender flare, up to a maximum of 2" from the body may be used, but the overall body width must still be maintained at a 68" maximum.
  4. Rear quarter panels can extend back to 48" maximum at top and may incline down to 44" maximum at bottom measured from center of rear axle to rear of car.
  5. Ground clearance on rear quarter panels must be a minimum of 8" and a maximum of 16".


  1. The rear spoiler must be clear one piece lexan with a maximum height of 5" from the rear deck and must not have any writing or stickers on it.
  2. The rear spoiler must be non-adjustable (no hinges or slides).
  3. No metal Gurney tabs permitted. Lexan may have brake (top only) for rigidity.
  4. Spoiler maximum height from ground is not to exceed 50".
  5. A maximum of four vertical supports may be used to fasten the spoiler to the rear deck. These supports may not exceed 2" in vertical height and 10" in length.


  1. Must be a maximum height of 47" and minimum of 40" from the ground.
  2. Rear deck lid (i.e. trunk lid) must be fully enclosed from quarter panel to quarter panel and have a minimum height of 9" and a maximum of 14" in vertical coverage behind the fuel tank.
  3. Left and right rear trunk lids must be symmetrical in size and shape and show no specific bulge or extension to cover fuel filler hose or apparatus within the 9" to 14" of vertical coverage. This panel must completely cover the fuel cell, filler hoses, and vent lines.
  4. Older cars with tall gas tanks may have a step in the deck to accommodate the tank.
  5. The fuel tank must be completely enclosed from the bottom of this panel to the bottom of the fuel cell.
  6. The fuel cell must also have both sides completely covered by sheet metal in addition to the container it is enclosed in. Within these dimensions there can be no openings.
  7. No openings from top of fuel cell to bottom of trunk lid are permitted.

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