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: [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: [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. The hood, nose, and front spoiler can be no wider than 36" and no narrower than 24".
  2. The nose-piece must end at the front of the shock towers.
  3. The spoiler must be separate.
  4. Shock covers or deflectors may not be part of or riveted to the nose or spoiler exceeding the 36" width maximum.
  5. Fabric shock covers are permitted as long as they are used for the prevention of dirt getting at the shock piston and not used for any aerodynamic advantage.
  6. The front spoiler must not extend any more than 20" in front of the front axle centerline.
  7. The front spoiler must be non-adjustable (no hinges or sliders).
  8. The hood shall be considered from the front roll cage to on top and even with the front of the radiator.
  9. The nose piece shall start where hood ends and end at the shock towers!
  10. Both hood and nose may have 2" maximum lip up on both sides following the contour of the body. Both lips must be symmetrical!
  11. The hood, nose, and spoiler may not overlap each other's location on the frame.
  12. Any part of hood may not exceed 10 degrees nor can sheet metal have an opening or extrusion between the hood and nose.
  13. The hood must extend over the radiator and have complete sides.
  14. Front spoiler may have 2'' maximum lip up or down on both sides following the contour of the spoiler, not exceeding the maximum width of 36 inches.

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  1. The hood must be fully enclosed.
  2. Two options of hood scoops mounted on top of the hood for the purpose of enclosing the carburetor, or ram air will be permitted providing they meet the following specifications.
  3. Both style scoops may be made of fiberglass.
  4. Ram air type scoop: Maximum length, 30" measured from rear motor plate to front of hood scoop. Maximum width 18". The front vertical opening of the scoop can be a maximum of 6" at the beginning of the scoop only. The overall height of this scoop must maintain a minimum of 8" of vertical vision for the driver. This measurement will be taken from a horizontal line from the highest point of the hood scoop to the lowest point of the front roll cage and/or roof. Hood scoop must be fastened to the hood and completely enclose the carburetor and air filter.
  5. The conventional no ram air scoop: a maximum of 25" is permitted from center of the carburetor forward to end of scoop! The width permitted is a maximum of 22". The height must maintain a minimum of 8" of vertical vision from the top of the scoop to the lowest point under roof or roll cage, and completely enclose the carburetor and air filter.


  1. Any horizontal body support, other than the inner pods, whether in front or rear must be a maximum of 1" deep by 1" thick tubing or flat stock only.
  2. No inside or outside wings, spoilers, air foils, or wind deflectors are permitted.
  3. No double panels that create a wing effect will be permitted.
  4. A 1" maximum reinforced lip will be permitted on all lexan, but all specified measurements must still be maintained.
  5. All inner sheet metal used must completely cover areas from door to door, quarter panel to quarter panel. No holes or openings are permitted in this area.
  6. No vertical fins, air dams, or fairings permitted on the sides or behind the roll cage.
  7. Sheet metal must be a flat single plane across the inside of the car with the exception of two stiffening bead rolls or stiffening breaks for the purpose of stiffening the wing only. Bead rolls or breaks may not exceed 1/8" in height and ½ inch in width.
  8. No covered roll bars are permitted. Sheet metal that is one-piece and part of a body panel bent around tubing (for purposes of protecting the driver or finishing off panel) is not considered an aerodynamic advantage provided it is not to excess.
  9. No louvers or holes in the interior or exterior sheet metal are permitted with the exception being the cooling of the radiator, engine, and oil cooler.
  10. The floor pan or under pan may not be any wider than the frame, from front to back, and may not have any lips or fins facing downward.


  1. The Track or series handicapper reserves the right to issue or change a car's number to prevent duplication and maintain proper records.
  2. Team cars must be clearly distinguishable from one another and use a different number or letter.
  3. All numbers and letters will be limited to three digits. If three digits are used, two shall be primary numbers. Numbers are required on roof, nose, rear deck and both doors.
  4. All numbers and letters must be a minimum of 18" high on the roof and doors, and 8" high for the rear deck and nose. All numbers and letters must be of equal size and painted or decaled. If numbers "3", "6" or "9" are used make sure that they are distinguishable.
  5. Nerf bars must not block visibility of number.

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DRIVER NAME (Recommended):

  1. Letters of driver's last name must be a minimum of six inches in height and be positioned under, through or above number on both sides of the car

SAIL PANEL: (Modified Only)

  1. Total Height: To be measured from the ground to the highest point. 65"
  2. Total length: To be measures from the center of the rear axle.
    • 48" from the center line to rear of car
    • 12" from the center line forward
  3. Maximum vertical lips: From door up- 2" From roof down- 2"
  4. Degree of angle from vertical lips (upper and lower) to rear plain of drivers seat: 22 degrees
  5. Sail panels must mirror size and shape side for side


  1. Only 2 x 4 box frames are permitted between axle centers, front and rear. The 4" side must be vertical. Frame rails must be steel only. All 2 x 4 rails must be .120" wall thickness only. At the discretion of the officials, it may be necessary to drill a 3/16" hole in frame rail for inspection of thickness. No other holes will be permitted. All tubing permitted for the frame rails must be either 1 1/2" dia. x .095" wall or 1 3/4" x .095" wall.
  2. Frame width is as follows: Front (at shock towers): 24" minimum, 35" maximum. Rear: 26" minimum, 35" maximum. The minimum frame width at the rear roll bar must be 26". All measurements are to be taken from the outside of the frame rails. These measurements shall be taken at both top and bottom of frame at its longest length. Clips, sub-frames, etc. are considered part of the frame.
  3. Minimum length of the 2 x 4 frame rails must start at 14" in front of rear axle centerline and extend to the front of the radiator. All kick up material must be same specifications as the roll cage or frame material. Left and right frame rails (both top and bottom rails) must be equal-distant from the driveline centerline in a vertical plane along the total length of frame. The only exceptions will be the lower left rear frame rail, which will be permitted at 4" maximum indent for suspension clearance, and the two upper frame rails in the engine compartment to allow for the clearance of large cylinder heads.
  4. Titanium or carbon fiber materials are not permitted on the chassis.

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  1. Seat and steering wheel must be centered in the frame.
  2. The seat must be a maximum of 16" from the center of the rear end to back of seat bottom.
  3. A high back seat made completely from aluminum is mandatory. No fiberglass or carbon fiber materials are permitted.
  4. Hans device or its equal recommended.


  1. Only one (1) radiator permitted and it must be centered squarely, not angled, in front of motor in a vertical position.
  2. No plastic or carbon fiber permitted.
  3. No auxiliary cooling tanks or catch cans are permitted in driver's compartment.


  1. The engine must be centered in the front of the chassis and placed in an upright position.
  2. Engine set back: minimum 56", maximum 66" with 1/2" absolute maximum tolerance. Set back will be measured from the center of the front axle to the rear machined bell housing surface of the engine.

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  1. Approved North American or Canadian manufactured manual shift transmission only. No automatics are permitted.
  2. No overdrive or underdrive transmissions are permitted.
  3. No running through reduction gears, transmission must be direct drive to rear end at racing speed.
  4. Transmission must have forward, neutral, and reverse gear in good working condition. From a neutral position with the motor running, a car must be able to go forward and backward in a smooth manner.
  5. Transmission must bolt to the bell housing.
  6. The car must start and move under by its own power.


  1. No chassis, driveline or suspension components made of carbon fiber are permitted.
  2. Two universal joints per drive line maximum.
  3. A drive line shield and 2 steel safety rings are mandatory (see safety rules for detailed requirements).


  1. Competition rears only.
  2. No hypoid type rears are permitted. (No 9" Ford type rears allowed)
  3. No limited slip type rear ends or hubs are permitted.
  4. No lockers or two speed rears are permitted.
  5. Rear end must have solid aluminum or steel spool only.
  6. Rear spindles may be steel or aluminum only. If aluminum, rear must be a one-piece tube and spindle with a minimum outside diameter of 2 7/8" and maximum inside diameter of 2 1/2".
  7. Live rear ends with aluminum or steel axles are permitted.
  8. The rear end or chassis must not be offset any more than 4" from center of the inside tire width! This will be measured from the inside of the left rear tire to the inside of the right rear tire, at axle height.

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