9HP MODIFIED SPRINT TECHNICAL RULES
Ages – 15 – UP with 3 year rule
Chassis frame and main roll cage must be constructed of the following: Front cage up right post to be 34”-
Seamless round tubing with a minimum of 1 1/8” dia x .090 wall thickness, or mild tubing.
No suspension parts allowed. Suspension parts include the use of shocks, springs, torsion bars, coil-
Foot hoop is mandatory (see diagram on page 21)
2. FRONT AXLE & SPINDLES:
Must use cotter pins or safety clips to prevent axle and spindle nuts from coming off.
If a front axle is used, it must be a one-
The use of rod ends or heim joints will not be allowed to be incorporated into either a one or two-
3. Designs not covered by the above must be approved by Grand Bend Speedway
All sidebars must be constructed of at least of 3/4” mild steel round x .065 wall thickness.
Right side must have at least one side bar mounted 20" -
Left side must have two parallel bars, the top bar to be mounted 20" -
A vertical bar must be mounted diagonally between the upper side bar and the top roll cage bar.
The attachment point of the vertical bar to the upper side bar will be 12" -
The attachment point of the vertical bar to the top of the roll cage bar will be 5" -
Left side door bars must have a minimum of two vertical door bars, being a minimum 3/4" dia x .065 wall steel tubing with a minimum spacing of 7".
All sidebars are to be constructed and mounted to provide maximum driver protection.
Bars may be welded, coupled, or coupled and pinned.
Steering Shaft Specifications:
Solid minimum .625 (5/8") diameter cold rolled steel.
Hollow minimum .750 (3.4") x .070 wall d.o.m. Tube.
Steering shaft must be one piece or two with extra universal joint.
Steering Wheel Mount:
Quick release mechanism is mandatory.
No loose fitting quick releases will be allowed.
Rack & Pinion:
Rack & Pinion steering boxes not allowed.
All steering bolts and nuts must be drilled and cotter keyed or safety wired or locking nuts.
Note: Any fastener (nut or bolt, etc.) of a component that would enable movement of or adjustment of spindles such as caster, camber, etc., must be drilled and utilize either a cotter pin or safety wire.
5. DRIVELINE COMPONENTS / CLUTCH:
Dry type engine mounted clutch is mandatory.
No transmission gearbox or other device, which permits a change of gear sprocket ratio while vehicle is in motion, is allowed.
Torque converters are not allowed.
Disc type clutches allowed (max. 4 disc).
No direct drives allowed.
Crankshaft extension no more than 7".
6. CHAIN GUARDS:
A chain guard designed to retain a broken chain from reaching the driver is mandatory.
Chain guard must curve 1200 around clutch and extend to rear of car to cover sprocket.
Chain guard must be constructed of steel or aluminum. (No plastic or lightning holes allowed.)
No automatic chain lubricators allowed, no chassis lubrication.
Hydraulic brakes only. (No scrub or band type brakes allowed.) All brake systems must be in good working condition.
All master cylinder and caliper bolts must be cotter pinned for safety or locking nuts.
Nylon lock nuts without cotter pins are prohibited.
8. WHEELS / HUBS:
5" or 6" wheels only, 5/16” wheel studs mandatory
No bead locking devices allowed.
No screws allowed.
No wheel discs allowed.
No clip on wheel weights allowed.
Both rear hubs must be locked to axle no floater hubs allowed.Brake hub and gear hub can be a floater type allowed.
Rims must be made of aluminum and be an approved racing rim (E.g.: Douglas, Van K) by Grand Bend Speedway and shall have an approximate minimum thickness. 5" rim should have 1/4” wall thickness.
9. REAR AXLE:
An axle clip must retain both rear hubs to prevent wheels from coming off. Maximum axle size 1-
10. WEIGHT / BOLT IN WEIGHT:
Mods Sprint cars must have a minimum weight with driver of 475 Ibs.
Any removable weight must be fastened with 2 bolts and be double nutted.
Any removable weight cannot be bolted to nerf bars, front and/or rear bumper and in front of front axle or behind rear axle.
Any removable weight must be painted white with your car number on it.
Any car found to be illegal shall be immediately disqualified, and the next finisher shall be called to the scales.
11. FRONT BUMPERS:
Front bumpers are mandatory. Must be constructed of minimum 3/4" o.d. x .065 wall and a maximum of 1" o.d. mild steel tubing.
Front bumper must extend beyond all body parts.
Must not extend beyond the inside dimension of the front tires.
Must extend at least 16" forward of the front axle or spindle assembly.
The upper hoop must be a minimum of 4 1I2"and a maximum of 6" from the bottom of frame rail.
The upper hoop must be supported by at least 2 vertical bars in the front portion of the bumper by 3/4" x .065 wall or larger steel tubing.
No weights mounted to front bumper.
12. REAR BUMPERS:
Rear bumpers are mandatory. Must be constructed of minimum 3/4" o.d. x .065-
Rear bumper must be constructed with 2 horizontal bars wit11 a minimum of 2 vertical bars.
The horizontal bars must be a minimum of 5" and a maximum 7" apart.
Minimum height to be no lower than top of frame rail. Maximum width to be no wider than roll cage uprights.
Rear wheel protectors are allowed and may be fastened to the bumper in a safe secure manner. May not exceed outside of rear tires.
Rear bumper must be fastened on the back of the roll cage uprights.
Rear bumper must extend a minimum of 24" behind the rear axle.
13. NERF BARS:
Nerf bars are mandatory on both sides of the car. Must be constructed of a minimum of 3/4" x .065 wall o.d. and maximum 1" o.d. mild steel tubing.
Nerf bars are to be a minimum of 24" in length, measured from backside of nerf bar closest to rear tire in a straight line to where it attaches to front of car. Nerf bars to have a minimum overall height of 5" at the highest point and a maximum height of 7 W'.
Nerf bars must not extend outside of rear tires.
14. FLOOR PAN:
The car shall have a floor pan under the frame rail covering a minimum area from front frame rail to front of driver's seat. Main floor pan must be constructed of 22ga. Steel or alum..
Min. .100” steel plate or .125” aluminum plate must be bolted or welded under the driver’s seat or a roll bar 1 1/8 under seat. ( Mandatory )
15. ROLL CAGE & COCKPIT SPECIFICATIONS:
The roll cage must be a minimum height of 38" to a maximum of 44".
The top of the driver’s helmet must be completely below the bottom of the horizontal roll cage bars (2”).
A distance of 4" between the top of the driver’s helmet and the bottom of the horizontal bars is highly recommended.
The roll cage must be made of chrome-
The roll cage must be welded to the chassis in 4 locations.
The top of roll cage must have gussets in all 4 corners.
No sharp edges shall be left anywhere on the roll cage or brackets on the car.
The roll cage must have 2 vertical bars mounted behind the driver's head.
The roll cage must consist of continuous hoops front to rear.
The roll cage must be connected on both sides and in the back and front by a minimum of 3/4" tubing.
The driver must be able to climb through the space in the top of the roll cage.
Driver's head must not be outside of the roll cage at any point.
Roll cage padding on every bar within hand & foot area must be padded (Mandatory).
16. FUEL TANKS & FUEL LINES:
Fuel cells are mandatory and may be a foam or bladder type or alum. Or plastic tank
Fuel cells must be located in tail section with only the bottom section of tail being open.
No pressurized fuel systems allowed.
Fuel lines must be clamped at all connecting points.
Fuel lines from fuel cell to the fuel pump must have protective covering to prevent a cut. Covering must meet technical approval.
Steel braided line is recommended.
Car must have a fuel shut off valve. Must be located over the right side bearing hanger bracket and must be easily accessible.
No cool cans or other conditioning components. Max. 3/8" I.D. lines short as possible.
A tire brand and compound may be specified.
Slick type tires only. (No re-
No grooving of tires allowed.
18. CAR DIMENSIONS:
Wheelbase shall be a maximum of 48".
The maximum overall width shall be 54". This includes all parts of the car. The overall length shall not exceed 100".
19. BODY DESIGN:
The front nose section may be wedges hood, or standard sprint car style. The front nose section can be made of aluminum, fiberglass, or a poly-
All cars must resemble a sprint style car.
The nose shall extend from the roll bars to a minimum of 1" from the back of the front bumper to a maximum of 4".
The nose must be in side the front wheels.
All cars must have a sprint style tail section to be made of fiberglass or poly-
The tail section must be a minimum 2" from the axle to front face of tail section.
The tail section must be inside the rear bumper.
The tail section must not extend more than 29" from the axle.
The tail section must be mounted between roll cage hoops.
Body panels must be in place at all times. (Hood).
All cars must be neat and clean appearing at all times.
The intent of these body rules is to insure uniform style "sprint appearing cars."
Any cars not meeting these descriptions will be asked to make the necessary changes by the technical official.
Grand Bend Speedway reserves the right to refuse competition to any car not meeting or following these guidelines.
20. NUMBERS / LETTERING:
All cars must be kept neat in appearance.
Numbers and letters must be done professionally.
Numbers and letters must be done in contrasting colors.
Numbers must be located in each of the following locations:
Front of hood -
Tail section both sides -
Wing both sides -
Numbers must be easy to read for scoring purposes.
Chassis, bumpers, nerf bars, bodies, etc., must be painted, plated or finished in a professional manner. (Any cars in question will be at the discretion of the tech department.)
All cars must run a side panel wing only, with a maximum size of 10 1/2" high x 32" long and a minimum of 10" x 32".
Wing panels must be mounted on both sides of car.
Wing panels must be made of aluminum.
Wing panels must be clamped to roll cage. (No tie wraps allowed.)
23. SEAT BELTS:
All cars must have a 2” or 3" 5 point safety harness.
Harness cannot be cut or worn in any place. Any belts in question will not be allowed.
Belts must be 3 years old or newer – tag must be visible
Any belts mounted in an unsafe manner will not be allowed.
No mirrors will be allowed.
All cars must have an engine kill switch and is to be mounted in a location easily accessible to both the driver and the safety crew.
26. SEAT / HEAD SUPPORTS:
High back aluminum seat is mandatory.
Seat must be bolted in 4 places with minimum 5/16" diameter bolts.
Right and left side head supports are mandatory.
Must be made of aluminum and have a padded cover.
Head and neck or HANNS or ZAMP device is MANDATORY IN 2018
No two way radios allowed
Honda GX270 9.0 HP motor with a Honda GX390 13hp carburetor is mandatory. (New with new / Old with Old specs to follow)
Must be located on right side of car.
GX270 Motor Specifications -
Governor mechanism may be removed.
Decompressor mechanism may be removed
Block may be bored to three over-
Piston dish must be a minimum of .037".
Piston must be a minimum of .003" above deck.
Stock Honda rings must be used and installed properly.
Any ring gap allowed stock stamped 1:1 rockers only
Stroke shall be 58mm or 2.287" maximum.
Stock or .010" undersize rods allowed.
Stock air cleaner or snorkel type allowed. Any heat range spark plug allowed as long as the reach is stock with gasket no taper plugs allowed.
Stock valves and keepers, stellite ex allowed.
Valves may be refaced but not excessively.
Any valve spring allowed.
13 hp carb a stock Honda jet and emulsion tube allowed only. NO jets larger than 110 allowed . NO MODIFIED CARBS
Minimum head cc is 26.
3 Angle valve jobs allowed ..
Cylinder head thickness from deck surface to valve cover surface is 3.736" minimum.
19. Head gasket is composition .042" minimum after being compressed.
20. Any flywheel air gap allowed.
21. Any ignition timing allowed as per the flywheel key.
22. Carb throttle bore NEW 1.070" maximum. (13hp carb)
23. Carb venturi NEW .833 no go. (13hp carb)
24. Any vacuum operated fuel pump allowed.
25. Any camshaft timing allowed.
26. No metal may be removed or added to camshaft.
a. Cam lobe height intake NEW 1.240" minimum -
b. Cam lobe height exhaust NEW 1.240" minimum -
28. a. Maximum lift intake valve NEW .280".
b. Maximum lift exhaust valve NEW .275".
29. Camshaft may not have lobe separation angle changed from stock angle.
30. Fuel Any pump fuel and or appoved racing fuel allowed . NO alcohol, orMethanol allowed . NOTE: some pump fuel contains 8% alcohol is ok with additives .
31. 1 1/8” Header pipe is permitted with a maximum length of 24" including muffler. Exhaust must exit the left side of the car.
The pipe must enter the muffler by a minimum of 2" if clamped on.
All engines must be properly assembled in accordance with Honda shop manuals.( old with old / new with new )
All parts may be compared with a known stock Honda part to verify their originality.
Engine seals are mandatory on.Crankcase & head.
Keith Marshman, Dave McAdams or Gary Custer may only do seals.
Engine rules are the same as Junior Late Models except for the following changes:
1. 13HP carb & insulator NO MODIFIED CARBS
2. Any ignition timing by flywheel key
3. Crank balanced may be removed
4. GX270 New aftermarket piston rod allowed ARC-
5 MAX Horsepower with these stock parts is 14 HP MAX