Vintage Modified

Vintage Modified Rules

  1. 5500 LBS Single Engine Modified
  2. Engine
    1. Tractors are limited to one cast iron or aluminum automotive type engine no larger than eight cylinders
    2. 530 cubic inch maximum 
    3. All cylinder heads will be stock configuration limited to two valves per cylinder. No spread bore
    4. Harmonic Balancer must be surrounded with ¼” steel and covered with ¼” steel plate unless the balancer is SFI approved.
    5. All tractors must have engine side shields minimum .060 thickness made from steel or .125 aluminum thickness. Schields must extend from top of frame rails to bottom of the head. 
    6. Exhaust headers must be straight up
    7. Dead man throttle required 
    8. Hand throttle only
    9. All drive parts  must be shielded, all fans must be shrouded 360 degrees, electric fans are allowed
  3. Fuel
    1. All gasoline products allowed
    2. Alcohol is allowed
    3. No oxidizers or pressurized fuel tanks
  4. Driveline Components
    1. All automatics and manuals must have a neutral safety switch. 
    2. All automatics must have a reverse lock out
    3. All tractors with a automatic will use a SFI approved flex plate
    4. All tractors with a automatic must run a transmission blanket or ¼” thick steel from rear of the block to tail shaft housing from frame rail to frame rail, or must have SFI approved six buckle transmission blanket, or two 3 buckle transmission blankets or SFI approved safety shield attached to engine and frame.
    5. Manual transmission bell housing must be SFI approved.
    6. Flywheel assembly must be billet steel or aluminum flywheel and SFI approved. No cast iron allowed. All clutch assemblies will be steel and SFI approved
    7. All tractors using clutch/bell housing assembly will use an approved block-saver plate. Bell housing will mounted with eight ⅜” or larger grade 8 bolts. Four ⅜” or larger grade 8 bolts will hold bell housing to back of block and four ⅜” will hold bell housing to the block plate. The four bolts holding bell housing to the block plate will be between the bolts holding bell housing to block.
    8. Driveshaft must be shielded 360 degrees from one end to the other with a minimum of ¼” thick steel visible at either end.
    9. Agricultural 2wd rear-ends and outboard planetary rear ends will be allowed.
    10. Maximum frame length is 14 feet from the center of the rear axle to the furthest most point of the tractor
    11. All tractors must have a wide front end and must track close to rear tires
    12. All tractors must have individual working rear brakes
    13. All tractors will required to have a roll bar or roll cage
    14. All roll bars must be capable of supporting the weight of the vehicle
    15. All cages minimum or .120 wall thickness tubing. Minimum O.D. 1 ¾” steel or 1 ½” chrome moly tubing.
    16. Seat belt or harness is required (5 point harness recommended)  
    17. All tractors must have a working kill switch. Kill switch will be mounted a maximum of 48” above hook point and within 6” of center of pulling vehicle. Kill switch ring will be 2” minimum diameter and must be steel 
    18. A white light automotive quality minimum 2” in diameter must be mounted directly above or below the safety kill switch at the rear of the tractor. Light is activated by a shift lever such that it will be lit only when the tractor is in reverse.
  5. Drawbar
    1. Must be clear and visible for sled to hook
    2. Must be rigid in all directions (no floating hitches) and securely mounted to the tractor
    3. Must use steel hitch no more than 1 ½” thick and no less than 1” thick in all directions, hitch hole must measure 3”-3 ¾” 
    4. Must not be shorter than 18”  measured from the center of the rear axle to the hook point. Maximum drawbar height is 20”
    5. All drawbars must be locked in place after height is set at each event
  6. Tires
    1. Maximum tire size is 24.5-32 or 20.8-38
    2. Must have fenders
  7. Stabilizer Bars
    1. All tractors must have stabilizer bars (wheelie bars)
    2. Must be capable of supporting the weight of the tractor
    3. Bars must extend no less than 32” behind the center of the rear wheel and a maximum of 10” from the ground. Wheelie bars must have a vertical support base, no wheels on the ends or the bars.
    4. Pads must be 4” or more
    5. Rear weights must not extend past the rear tires 
  8. Driver Safety
    1. Driver must be 18 years old or have signed parent/guardian permission and capable of driving a vehicle in a safe manner.
    2. All drivers must wear SFI approved helmet
    3. SFI approved fire safety suits are recommended but not required.
    4. All tractors must have a fire extinguisher
    5. All tractors must have a battery disconnect
  9. Safety
    1. Wheelie bars
    2. Roll bar/cage
    3. Fire extinguisher
    4. Battery disconnect
    5. Fan Shroud
    6. Drive Shaft shroud
    7. Engine side shields
    8. Dead man throttle 
    9. Fuel shut off
    10. Seat belt
    11. Harmonic Balancer shield
    12. Transmission Blanket/Shield
    13. Kill switch
    14. Reverse Light