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Driver's Information

Four-Cylinder Rules

(FWD and RWD 4 cylinders)
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IF YOUR NOT LEGAL THE FIRST NIGHT YOU DON’T RACE
(Any rules questions please contact Ryan Powell)

Minimum of a neck brace is required in all classes at any time you are on the track

Overall – 3100 lbs – full frame pocket to pocket with steel body @ 59.0% left (steel doors, fenders, and quarter panels)
3200 lbs – full frame pocket to pocket with a template or aluminum body with 59.0% left weight (ALL WEIGHTS ARE WITH DRIVER AND HELMET)

All added weights to car should be painted white and have your car number on it. No weight below the frame.  All added weights shall be securely fastened with minimum ½” steel grade threaded rod. You must be 100% legal to run in this class or you will race with the pro late model division.

  1. Minimum wheelbase: 105
  2. Maximum track width 78” (by use of toe boards anywhere on wheels)
  3. Spoilers 6×60 centered on car no higher than 42” from the ground
  4. Minimum ride height 5”
  5. Minimum roof height: 47” (measured anywhere)
  6. Fuel cell mounted above centerline of rear end, 8” minimum clearance.
  7. Any template appearing body, aluminum or fiberglass, is allowed (see weight rules above). No outlaw-style bodies. Aftermarket nose and tail pieces are OK.  Must be mounted in a factory manor (do not lay them back) and body’s should not have rake in them. No splitters unless manufactured into the aftermarket nose. Aftermarket cars should weigh 3200 lbs. 
  8. Cowl and be used but air cleaner cannot be visible.
  9. Building of dash, front/rear firewalls OK. Minimum 1/8” steel under driver, no exceptions unless stock floor pan is used. Cockpit must remain open. Front to back under driver’s seat must be steel.
  10. Racing type seat is mandatory. No fiberglass.
  11. Seat belts must be properly installed-five point system only! Belts should be no older than 3 years old and in good condition.
  12. Full charged and properly mounted fire extinguisher is mandatory.
  13. Batteries must be securely fastened and covered.
  14. No mirrors, no radios
  15. Window net is mandatory.
  1. Frames must be stock spring pocket to spring pocket
  2. Safety constructed 4 post roll cage with minimum 3 bars on driver’s side. Using 1 ½” OD tubing and .090 wall. Front and rear hoop OK
  3. Driver’s door must have a 10” x 30” x 1/8” minimum steel plate welded or bolted securely to the cage.
  4. Tubular steering shaft with minimum of two universal joints OK. Collapsible steering shaft highly recommended.
  5. Stock mounts, stock location, stock rear frame rails may be replaced from behind the spring pockets rearward to the bumper with 2” x 3” steel tubing.
  6. Stock 4 link only in stock location. Ten or twelve bolt GM rear ends OK. Ford 9” rear ends also OK. All rear ends must have steel tubes only and center section.  Any aluminum center section must add 20 pounds. No quick change rear ends. No other modifications. ( no limited slip differentials like Gold Tracks or similar) NO ALUMINUM SUSPENSION PARTS, ANYWHERE! We recommend aftermarket rear axles for added strength. Adjustable Heims on rear trailing arms OK. Leaf spring cars must add 50 pounds.
  7. A-arms, rotors, calipers, tie rods, steering box, etc to be stock OEM. Trailing arms can be aftermarket or homemade and mounted in rubber or spherical bearing. NO THREE LINK OR PANHARD BARS.
  8. Screw jacks on all four corners OK
  9. Minimum spring diameter is 5” racing style.
  10. Aftermarket upper A-arms OK. No adjustable ball joints.
  11. Any steel body shock with no Schrader valve, with no internal or external bump springs. Tie down shocks OK Must meet 5” ride height rule before and after the race.
  12. Aftermarket gas pedal, brake pedal, in car brake adjuster OK
  13. Rear disc brakes OK. Single piston steel or aluminum calipers OK. ALL FOUR BRAKES MUST BE OPERATIONAL.
  1. Engine must be stock appearing, all cast iron – Maximum 2” set back, but must not exceed 4” This will be measured from number one spark plug to ball joint centerline. Setback between 2” and 4” require 50 lbs. added to the right front corner of the car per tech officials discretion.
  2. Roller cams, roller rockers assemblies OK
  3. Intake: cast iron or aluminum
  4. Carbs: 2 or 4 barrel OK
  5. Max. adapter spacer is 1” any material
  6. No aftermarket electrical fuel pumps.
  7. Stock style HEI or MSD style ignition OK
  8. Any header with any exhaust, single or dual. Must exit behind the driver and not pass through driver’s compartment. 100DB muffler Mandatory!
  9. Transmission: automatic w/ stock 10.5” torque converter or manual with 11” or mini Clutch OK. Reverse gear is mandatory, no direct drive or aftermarket transmissions. Aluminum flywheel is OK. No Quick Shift Transmissions
  10. Car must idle in gears w/ hands on the steering wheel.
  11. No transmission coolers in driver’s compartment.
  12. Drive shaft hoop mandatory!
  13. Stock or aluminum radiator in stock location. NO ANTIFREEZE!
  1. Tires – Hoosier 800 Tires
  2. All wheels are to be 8” steel safety type only – with 1” lug nuts recommended.

ANY INTERPRETATION OR CHANGING OF THESE RULES IS AT THE DISCRETION OF THE OFFICIALS. THEIR DECISION IS FINAL. ANY MAJOR INFRACTION WILL BE ADDRESSED AS A FORFEITURE OF POINTS AND MONEY EARNED FOR THE NIGHT. THIS WILL BE AT THE DISCRETION OF THE TECH INSPECTOR. FIGHTING WILL NOT BE TOLERATED.

4- or 6-cylinder front wheel drive or 4-cylinder rear wheel drive compact cars only. No full-size cars allowed. No SUVs, Cross Overs, or Vans permitted. Wheelbase must be between 90 and 107 inches. 75” max width, as measured by Toe plates outside of tires. No convertibles or all wheel drives allowed. No all-wheel steering allowed. No rear or mid-engine cars allowed. No power adders of any kind allowed. (superchargers, turbos, or chemical adders included).
Cars must maintain OEM engine manufacturer. Example: Ford to Ford, Chevy to Chevy, Honda to Honda, etc. No aftermarket blocks, Stock type cylinder heads with stock casting from the same engine family as the Block. Throttle body must be attached to the intake manifold at the stock location. Aftermarket intakes are allowed. One fuel injector per cylinderAll forward and reverse gears must work.

Single exhaust only, and must be sealed with no leaks, no tubing larger than 2.5” diameter will be allowed anywhere in the exhaust system. Exhaust must exit behind the driver and away from the fuel cell.

Roll cage must be a 4- or 6-point design and be constructed of 1 ¾ or 1 ½ .095 or thicker steel tubing. Must be roll cage tubing. No tack welds. Cage must be attached to the floor/unibody frame of the vehicle by welding to the rocker rail or to ¼ minimum thickness sandwiched plates bolted to the floor. Roll cage must include a minimum of 3 door bars per side connected with spacing bars between each door bar. Drivers’ side bars must be arched away from the driver’s seat area.

All exterior trim including lights, body moldings, mirrors, etc. must be removed. All cars are required to have Complete bodies including both bumper covers and deck lid. The roof and A and C pillars must remain stock steel but can be skinned. Aluminum sheeting will be allowed for bodies. No downforce style, shovel, or dirt late model style bumper covers are allowed. Doors must be welded shut or bolted. Doors can be skinned. Skirting is permitted but must not extend more than ½” beyond the outside width of the tires. No sharp edges or ends on skirts. No splitters or rear air diffusers allowed. No bars can come through any body panel or bumper cover. No bars below the bumper cover except the crash bars for the fuel cell and they must be forward of the start of the rear bumper cover. Rub rails are permitted on both sides at doors only. Can only be mounted flush against the door skins. No nerf bar style rub rails. Rub rails may be 1”x1” steel or clear plastic or Lexan decal protector type. Both mounted flush with no rough or sharp edges

Windshield can be stock or replaced with Lexan. If using Lexan a center brace supporting the Lexan is recommended. No Lexan or any other material covering the passenger door window. Side quarter windows and back windows are optional but must be Lexan and made to replace stock side windows of the cars make/model if included.

Rear deck spoilers are allowed. Maximum spoiler size is 5” Tall and 60” wide. Maximum height of spoiler may not exceed 5” above deck lid surface. Fabricated spoilers must be see-through (Lexan)

Car must have a stock Appearing frame, firewall, and floor pans from the firewall to the center of the rear wheels. NO TUBE CHASSIS ALLOWED. No open holes in the firewall or floor pan allowed. Any holes or repairs must be made using the original thickness steel only. No aluminum allowed. Trunk floor may be removed or modified to allow for fuel cell installation.

Base weight: – 2250 lbs
58.0% Max left side weight
  1. Four cylinder or Six cylinder front passenger cars are eligible.
  2. No full-frame cars allowed.
  3. Cars must utilize engine available in the car/body style being used.
  4. No all-wheel drive. No all-wheel steer. (Front Wheel Drive ONLY!)
  5. A functioning diagnostic plug under the dash must be present.
  6. Stock Bodies

Four or Six cylinder naturally aspirated engines will be allowed. Engine must be completely stock as manufactured by factory including engine, driver train, ignition components, suspension components, and fuel system, except as noted below. Only the complete stock engine/drive train for the make and model as delivered from the factory may be used. No rotary engines.

  1. Stock intake manifold must be used with no modifications.
  2. Stock exhaust or headers allowed. Two-inch max diameter. Removal of smog, emission, air conditioning, and power steering parts are permitted.
  3. A complete exhaust system must run at least 24- inches of exhaust pipe. Removal of catalytic converter is allowed.
  4. Last 24” of exhaust must be 2” Max Diameter.
  5. Must use stock style starter. Battery may be relocated to an area behind driver must be secured and covered.
  6. Transmission must have working forward and reverse gears.
  7. All six cylinders will run automatic transmissions.
  8. No Racing clutches allowed.
  9. Turbo chargers, super chargers,  or nitrous oxide are NOT allowed.
  1. All exterior trim, included lights, body moldings, mirrors, etc. must be removed. Drivers and passenger door must be welded or bolted shut.
  2. Stock OEM Bodies  NOTE: All Bodies subject to inspection and approval by the technical director.
  3. Cars must have stock frame and stock floor pan. All openings in firewall and floor pan must be covered. Firewall must be stock, Hood must be secured with a minimum of two hood pins each. (NOT BOLTS).
  4. Windshield must be replaced with 3 bars of 3/8” diameter. Bars must be welded to the roll cage in front of driver. All glass must be removed from the vehicle.
  5. Spoilers will be allowed Stock or Aftermarket. Aftermarket spoilers can be a maximum of five inches tall and 50 inches wide. And must be clear material.
  6. All flammable interior trim is to be removed from passenger compartment and trunk. No removal of ANY interior sheet metal panels except in driver’s door to make room for cage.   Heating and air conditioning box may be removed.
  7. Racing Seat is required.
  8. Steering column and pedals should remain stock. All air bag components must be removed.
  9. A full four-point standard cage is required. Cage must go completely from left to right side and may not protect just the driver’s side. All cars must have a minimum of three door bars on the driver’s side and two on passenger side. Minimum 1/8” thick plate must be welded or bolted to the outside of the driver’s door bars.  Cages must be welded or bolted to the floor of the car. All cars must have crush zones and a maximum of two rear down bars may be used to support the hoop. These bars may run from the top of the hoop behind the driver and extend to the front of the rear firewall. A single cross bar or “X” may be used between these down bars. Rear down bars MUST be attached to the trunk FLOOR.  Main cage must have at least two bars running from left to right, between the upright, behind the driver.  One at floor level, and one at shoulder height of the driver.  Roll Cage tubing must be minimum 1 1/2″ diameter and .095 thickness.
  10. Main Shut-Off switch for electric fuel pump must be easily accessible by safety personnel, and clearly labeled as such.
  11. Cars must have tow chains or tow hooks front and back for tow truck pick up.
  12. No Lead added
  13. Cars must be neat in appearance and neatly numbered on BOTH SIDES and TOP.
  1. D.O.T. approved passenger car tires only. No “made for racing” tires.  Tires can be 13, 14, 15 and 16 inches maximum.  They can be 75,70,65, or 60 series.
  2. No wheel spacers of any kind allowed. Racing wheels are allowed.
  3. Steering and suspension shall remain stock and in stock location. OEM-style shocks, struts, and springs ONLY may be used. No heating or cutting of spring allowed.
  4. For cars that do not have camber adjustments built in from the factory, modification or existing parts, to allow for camber only adjustments will be allowed, but subject to technical director approval. Front and Rear Camber adjustment is 1” maximum. 
  5. All four brakes must remain stock. ABSOLUTELY NO ABS OR TRACTION CONTROL. All ABS sensors must be disabled.
  6. Cars that have fuel tank mounted in front of rear axle may use stock tank. If tank is not mounted in front of rear axle, a fuel cell or marine type tank must be used and securely mounted in the trunk area of the car. Trunk mounted tanks cannot be mounted within ten inches of the rear trunk panel and may not extend beyond the side frame rails. All fuel tank installations must be centered between the rear wheels. 
  7. Racing Fuel Cells HIGHLY recommended!
  8. No emergency brakes allowed.
  9. No aftermarket springs or Shocks. One shock per wheel.
  10. Aftermarket quick release steering wheel will be allowed for safety.
  11. Wheelbase 92”- 107”
  12. No Coil over or adjustable struts.
  13. No adjustable struts.
  14. Factory coil overs allowed ( No Racing aftermarket Coil overs allowed)

  1. See “General Safety Rules” page for track specific safety rules.

Minimum of a neck brace is required in all classes at any time you are on the track

  1. Any manual or automatic 4 cylinder front when drive or any 6 cylinder front when drive with an automatic
    transmission can be used. Exceptions – No convertibles, No turbo or super charged engines, No multi carbs,
    No rotary engines, No mid or rear engine cars and No Cosworth engines. Factory stock fuel injection only.
  2. All rear and side glass must be removed, all windshields to be stock or Lexan. All cars must have full
    windshield. Side and rear windows can be replaced with clear Lexan.
  3. All exterior chrome, trim, molding, mirrors, and lights must be removed.
  4. All door panels, carpet, headliner, plastic, upholstery, and any other flammable materials must be
    removed. All springs and latches must be removed. Dash pad can be replaced with a homemade style
    dash.
  5. Any body must have stock or aftermarket stock nose and tail piece. No wedge style nose. No front splitters.
  6. Fully charged and properly mounted fire extinguisher is mandatory; 2lbs minimum, within drivers reach.
  7. Spoilers 5” centered on the car and no higher than 42” measured from the ground.
  1. Roll bar over drivers head required. Cages or bars shall be installed and constructed so the B hoop is
    higher than drivers and passengers head. Cage or bar must be mounted to the floor pan. A 12”x12”
    (Appox.) steel plate should be used at hoop mounting points, gussets at main intersections recommended.
    Door bars are mandatory.
  2. Front/rear bars – You are allowed to run up to 1 ¾” dia x .090 bars down to the rear struts off the back of
    the main cage as well as between the rear struts. You are allowed to run up to 1 ¾” dia support bar
    between the two front strut towers. We are allowing the placement of front and rear bars solely for the
    purpose of safety and to try to keep the rear of the car from folding up so easy. Maximum or any tubing size
    with be 1 ¾” round or square; there will be no 3” or 4” channel. The rear bars may extend rear-ward from
    the top of the cage behind the driver, angling down towards the rear trunk area. You are allowed to have
    one 1 ¾” x .090 piece of tubing run between the two front frame horns of your car. This bar will be back
    from the front edge of the frame horn so it won’t be mistaken as a support bar for your bumper. This bar is
    intended to keep the frame horns in place and to assist with the mounting of your radiator.
  3. We suggest having a piece of tubing welded flat on the trunk floor, back near the kick-up of the very rear of
    the trunk area. This is the material that your rear bars will attach to, no bars of any kind will extend out
    through the rear of your trunk area; any bars out past this point will need to be cut before racing. You may
    have an X in between your diagonal bars.
  4. Minimum of 4 point aftermarket full race harness is mandatory! Does not have to be date checked but
    must be in good condition. Aftermarket racing seat is mandatory, it must be mounted properly. No
    fiberglass seats allowed.
  5. Window nets are required
  6. A secure towing device (hook, cable, etc.) must be installed both front and rear. Securely fastened and
    located so as not to be a hazard in the event of contact.
  7. Eye protection and gloves are also MANDATORY!
  8. Full fire suits are MANDATORY
  9. Helmets to be Snell SA-95 or newer required, Snell SA-2000 recommended.
  10. Two way radios are not allowed. No mirrors of any kind allowed.

  1. Complete stock motor and motor must match same make of the car (Honda-Honda, Dodge-Dodge, etc.)  You may remove excess wiring and sensors at your discretion. Aftermarket header is OK.

  2. Batteries must be securely tied down and/or relocated and mounting tray reinforced. Batteries may be relocated, however, they must be securely fastened and within a completely enclosed battery box, preferably metal with metal retaining bar. Box and battery must be installed in a safe and responsible manner.

  3. Stock, unmodified transmission and transaxle, as manufactured and delivered. With working forward and reverse gears.

  4. A complete and leak free exhaust system with a maximum size of 2” O.D., run from engine to an area behind the driver and must include stock muffler is mandatory. MUST EXIT UNDER CAR OR OUT THE REAR OF CAR. Removal or gutting of the catalytic converter allowed. Loss of muffler will be grounds for black
    flag. Sound limit 85 dba.

  5. Any radiator allowed which will fit in stock brackets. 180 degree fan shroud required. An overflow container mounted in engine compartment. Water only in radiator; no anti-freeze.

  6. Cars without the fuel pump mounted in the tank must use a cell or marine type tank mounted in the trunk. Stock tanks are allowed if mounted in the front of rear axle. Cells are recommended and can be mounted to the trunk floor or in a built cage. Bottom feed cells are OK only if mounted to stock floor pan. Tanks must be securely fastened to the trunk floor with a minimum of two, 1” x 1 1/16” straps in each direction, bolted through the floor using double plates or installed in a safely constructed frame. Tanks shall be mounted 10” from rear of the back panel and 8” off the ground or beyond the frame rails. (cell required on wagons). Cars equipped with electrical fuel pumps must install a toggle type switch clearly marked at the base of the drivers pillar. Adjust coil over sleeves with stock type strut only. No adjustable coil over shocks.

  7. Any fuel allowed except alcohol.

  8. Steering and suspension shall be stock only. Absolutely NO modifications other than listed below, Ride attitude must be maintained at all times. No sway bar rule. Cutting springs down or using progressive aftermarket stock style springs are OK, however, this must be kept to a minimum and will be policed to
    ensure no one car dominated because of it. Must have stock struts and non-adjustable shocks. Spring rubber are OK.

  9. Minimum 18” high numbers in a contrasting color are required on both doors AND on the roof of the car as well as a 4” high number on the upper left or right side corner windshield.

  10. Cambering of front wheels is allowed but you can not alter the stock suspension parts to do it. What you get with stock parts is what you race with. Aftermarket OEM replacement struts that have the camber adjustment already built in are OK. Open camber rule. Maximum of 1/8” difference front to rear (comparing left side to right side) on wheel base measurements. (In other words 1/8” max lead in the rear end.)

  11. All cars must measure the same track width across the front axle and across the rear axle. (all wheels must be in line with each other front to back) No toeing of rear wheels at all in any direction. Rear tow must be zero!!!

  1. Hoosier 790 Tires or Stock type tires only. 165-195 60/65/70 13” or 14” or 15” D.O.T. approved tires only.
  2. Offset need to be the same front to rear but can be different from side to side.
  3. No grooving, capping, or soaking of any kind allowed. 2/32 tread in two groove rule applies on RIGHT FRONT ONLY.
  4. Rims shall be 15” diameter or smaller but must all be the same size rim.
  5. Oversized lug nuts OK.
  6. Right front racing type safely wheels are mandatory, the other wheels can be racing wheels or stock.
  7. No made for racing tires, PERIOD! Nothing less then 400 tread wear.

The interpretation of these rules is at the discretion of the track officials. Safety rules will be strictly enforced.  Do not change things on cars in this class other than directed above! You should assume cars will be raced as delivered from the factory with the few changes listed above.

You must be 14 years old to race in this class and consent forms from both parents signed prior to racing. At this age you will be asked to attend practice nights to be eligible to race on Saturdays

Plymouth Motor 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.

 

ANY INTERPRETATION OR CHANGING OF THESE RULES IS AT THE DISCRETION OF THE OFFICALS. THEIR DECISION IS FINAL! ANY MAJOR INFRACTION OF RULES WILL BE ASSESSED AS A FORFEITURE OF POINTS AND MONEY’S EARNED FOR NIGHT. HEAD AND NECK RESTRAINT SYSTEMS HIGHLY RECOMMENDED! BE PREPARED TO BE CHECKED FOR ANTIFREEZE EVERY WEEK BEFORE PRACTICE. IF CAUGHT DURING OR AFTER A RACE WITH ANTIFREEZE COMING OUR OF YOUR CAR YOU WILL BE FINED, DISQUALIFIED, AND FACE SUSPENSION. 

Plymouth Motor Speedway
11631 12th Road
Plymouth, Indiana 46563
574-914-0104
plymouthmotorspeedway@gmail.com


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