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Plymouth Speedway Rules
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600cc Winged Class Rules
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2013 Restrictor Class Rules
Updated April 10, 2013
 
All drivers are required to have their own Raceivers for one-way communication with race director official.
Top 5 feature finishers will be required to go to tech area after the race.
 
Age Requirement
1. Driver’s age minimum is 9 years old. Certified copy of birth certificate is required.
 
Roll Cage
1. Roll cages shall be at least 1-inch .062 wall thickness, or 1 1/8 inch .065 wall thickness, or 1¼ inch .065 wall thicknesses. Roll cage shall be made of chromoly steel or equivalent material.
2. The front section of the cage shall be no further back than the steering wheel.
3. Roll cage shall have sufficient fore and aft bracing and strength to support the weight of the car and driver in case of an upset.
4. Cage shall have gussets at the intersecting bars to the uprights.
5. Bends must have at least 3-inch radius. No square or pointed corners allowed.
6. Roll cage must be a minimum of 3 inches above the driver’s helmet.
7. It is mandatory to install a cross brace behind the seat to support the shoulder harness.
 
Bumpers and Nerfs
1. Cars must have bumper extending beyond the front and rear tires. Nothing may extend beyond a tangent line from the outside edge of the tires to the bumpers. Nothing may extend beyond the outside edge or the tires or wheels, whichever is the widest.
2. No sharp corners or designs as to hook or damage.
3. All cars must be equipped with nerfing bars. Nerfing bars must extend to inside edge of tires, but not beyond the outside of tire.
 
Electric and Electronics
1. On and off switches must be on dash, top of the cowl or on steering wheel. On/off switch must be connected and functional. No radio communication is allowed with the car or the driver.
 
Battery
1. All wet cell batteries mounted in the cockpit must be covered and vented outside the cockpit area.
 
Fuel
1. All 600 cc Open Class cars must run Nationally approved fuels. Gasoline or Methanol allowed. No additives or enhancements are allowed.
 
Weight
1. Weight is 700 pounds with driver.
2. Any material used for the purpose of adding to the car’s total weight must be firmly attached as a part of the car’s structure. No liquid or loose ballast, i.e., water, fuel, oil, sandbags, rocks, etc. allowed.
 
Motor Rules
1. Stocked 600cc stock and bore.
2. Must run methanol or track approved gasoline with no additives.
3. No traction control devices of any type will be allowed.
4. Restrictor plates must be installed in the top half of boot. Fitting in the groove snuggly between the throttle bodies and the engine. All restrictor plates must pass the .750 Go - .7505 No Go, no tolerance will be allowed.
5. Top 4 will be inspected after feature finish or discretion of track officials.
6. No cones in carburetors or air box.
 
Suspension
1. Tread; Maximum 52 inches.
2. Minimum 32 inches, center to center of tires.
3. Wheelbase: Maximum 70 inches. Minimum 50 inches, center of front axle to center of rear axle.
4. Rear wheel drive only.
5. All suspension bolts except wheel nuts must be secured by some type of locking device.
 
Shocks
1. Any shock absorber legal, except no cockpit adjustable shocks.
 
Brakes
1. Brakes will be of sufficient strength so as to slide the wheels while the car is in motion at any given time.
 
Tires and Wheels
1. Any wheel size and tire combination may be used, but tires may not exceed 23 inches in height. Racing rubber only.
2. Air bleeders are allowed.
3. Wheels must be held on with 4 or more standard lug nuts or knock-off hubs.
4. Tires must be Hoosier tires with Right Rear Spec tire being Hoosier NMMA or ASCS2 along with the KS1 when released.
5. Tire durometer check should be done at least 15 minutes after the races to allow for cool down or durometer check could be prior to the event.
6. Front axle must be one piece solid front axle with no independent suspension of any kind.
 
Transmission
1. Any type transmission is legal on the 600cc engines.
2. Any car equipped with a shifting mechanism must have this device mounted in the driver’s compartment. Shift levers may be mounted outside the driver’s compartment on opposite side of car from the chain drive.
3. Chain guards will be made of .090 inch thick aluminum or equivalent and will run on top of chain from the front of the front sprocket to the center of the rear axle. Driver must not be able to touch the chain or sprockets while sitting in the cockpit.
 
Bodies
1. All cars must have complete bodies. Tail sections must be in place for time trials and all races.
2. There must be a metal firewall between driver and engine, made of 24-gauge steel or .0625” aluminum.
3. Body of car must be made of aluminum, metal, fiberglass or high impact plastic. All cars must be an attractive color or colors.
4. No rear view mirrors allowed.
5. The only part of the car allowed to be dismantled for driver to enter or exit is a quick release steering wheel hub.
6. Mudguards must be made of aluminum or fiberglass, and can be no less than 16 inches from the top of the cage.
7. All mechanically operated devices must be mounted below the driver’s shoulders for safety reasons.
8. All fuel tanks must be equipped with a one-way check valve designed to prevent spillage of fuel in the event of a rollover.
9. No mechanical, electrical or hydraulic adjustments are allowed in the cockpit area.
 
Numbers
1. All cars must have legible numbers in colors contrasting to the background on both sides of the car and on the nose.
2. Minimum height of numbers on the nose is 8 inches. Minimum height on the tail is 10 inches. Minimum height on both sides of top wing is 12 inches. Cars must have a 12 inch number on top of the wing facing the front of the car. Numbers should be separated from advertising so that they will stand out and can be readable by the scorers.
 
Wings
1. Minimum wing size is 10 sq ft. There is no maximum wing size in the restrictor class. Top Wing is not allowed to stick out past the rear tires on either side of the car.
2. Top wing is mandatory to enter a night’s event. Cars may finish without a wing if no replacement is available.
3. No mechanical, electrical or hydraulic adjustments are allowed in the cockpit area.
 
Plymouth Speedway reserves the right to change, delete or add to rules throughout the racing season.
The management reserves the right of interpretation of all rules and the right to inspect and reject
any car and/or driver, crew member, etc. during the racing program.
 
For any questions on the Plymouth Speedway rules, please call Tech Director Mike Zielinski 1-(574) 532-7969
 
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