2010 Rules and Regulations
Street: 9 points or less
Modified: 9.25-15.25 points
Unlimited: 15.5 + points
It is the competitor’s responsibility to read and understand these rules in total. Any modifications not specifically allowed in this document can be considered not allowed. Consult Miata Challenge event organizers for any clarifications needed prior to entering event. Miata Challenge reserves the right to re-class any car not deemed to be classed within the spirit of the rules by the entrant.
Properly installed SFI or FIA 5/6 pt harnesses, FIA or SFI seat, and SFI approved head & neck restraint are not mandatory but encouraged. No lightening points will be assessed for SFI or FIA 8855-1999 approved racing seats. 4/5/6 pt harnesses may not be used in conjunction with OEM seats. 4 pt harnesses must be ASM type.
90-05 Miatas must have a four point roll bar bolted or welded to the frame per Speedventures minimum safety requirements for open cars. Two point "style" bars will not be allowed. 6-8 pt cage is free.
Free all classes. Street & Mod must serve no other function.
Street must retain complete OEM dash, a real passenger seat, door cards and carpet. Carpet may be removed behind driver seat. No removal of any single component over 1 lb unless otherwise allowed for Street.
Mod may remove passenger seat, carpet, dash, heater.
Wiring harness – Free all classes
Items which may be removed free in Street and Mod
Door arm rests
Center console aft of shifter
Brake dust shields
Air Conditioning system
Power Steering system
Streetmust be OEM or OEM replacement and be made of DOT approved shatter resistant glass
Unlimited – Windows free
Street and Mod: Any battery in stock mounting location
Unlimited: Charging and starting system free
Master cut off switch
Free all classes
Suspension & Drivetrain
Street class may not use tires with UTQG tread wear rating of less than 140
Clutch- Free, all classes
Flywheel – Free, all classes
Wheel spacers free in all classes with these limitations
3mm maximum on OEM studs
20mm maximum on extended studs
All classes may use Miata 5 or 6 speed transmission
Final Drive Ratio
Street may use any USDM Miata ratio (3.9, 4.1, 4.3). Mod may also use 3.6, 4.875. Unlimited- Free final drive ratio
Quaife or OS Giken close ratio dog box conversions not allowed in street
Any Miata OEM or steel caliper, any rotor, soft lines, pads- Free all classes
Master cylinder - Free all classes
Proportioning valve - Free all classes
Street must retain functioning OEM parking brake mechanism
Mod and Unlimited – may delete emergency brake mechanism for non-street legal cars only.
Street and Mod may add no more than two 3” diameter holes in front bumper for cooling ducts without points penalty. Further modifications constitute Custom Front Aerodynamic Modification.
Engine and differential mounts
Free all classes
Connecting links for sway bars
Free all classes
Street may replace with OEM replacement urethane or hard rubber type. No solid materials, e.g.: Delrin, Aluminum, Acetal.
Mod - Same as Street but may use offset bushing or rigid materials without penalty
Street and Mod must use Mazda Miata factory control arms. May update / backdate. May add material but not remove material.
Unlimited - Free. May replace pivots with spherical bearings. May relocate pivot location up to 25mm from OEM location for that year chassis
“Coilover” herein defined as a damper assembly having either a threaded body, threaded sleeve or springs of less than 75mm ID.
Upper shock mounts
Free all classes
Free all classes
Street and Mod may not use aftermarket or modified OEM spindles. Update / Backdate OK
Alignment- Free all classes
Free all classes behind OEM cat location.
Street cars must have functioning catalytic converter. Function can be quickly verified with infra red heat gauge.
Mod and Unlimited may delete catalytic converter
Ignition – Free, all classes
Radiator – Type, free
Street must be mounted within 2” of OEM location in same orientation
Mod- Must be located within 2” of either bottom two, or top two OEM mounting points.
Unlimited- Location free
Coolant Reroute- Free all classes
Oil Cooler- Type, free all classes. Street and Mod must be located in engine bay and serve no other function.
Unlimited - Free
Fuel - Up to 100 octane unleaded pump gas, or E01~E100 allowed in all classes
Water or methanol injection allowed in all classes. Methanol can not be primary fuel source. Nitrous Oxide injection can not be used. Any competitor found using N2O will be banned forever.
Engine Swaps & Forced Induction
Non Miata engine conversions include points for LSD, internal, external, header, exhaust, subframe.
Forced induction Miata engine includes points for ECU, header, exhaust, internal, external mods
Body & Chassis modifications
Body Panel Attachment
Street & Mod may pin hood and trunk. Street must retain OEM hood and trunk hinges. Street may delete front hood latch if two pins are used.
Mod may remove all hood or trunk hinges and latches if 4 pins are used per panel
Street and Mod, body panels must attach within.25” of OEM locations
Unlimited- Body panel attachment free
Tire to Fender Clearance
Fenders may be rolled and or pulled to allow for tire clearance
Free in all classes. Street & Mod class must take lightweight body panel points if material is removed from OEM fender to allow flares.
Free, all classes. Street and Mod may not protrude more than 1.25” above surface of OEM hood.
Chassis Stiffening Braces
Free in all classes. Chassis braces can serve no other purpose in Street and Mod class.
OEM tow hooks may be removed. Must retain at least one front and at least one rear fixed or strap style tow hook at all times while on course.
Street and Mod: Can not modify tub except, and only to allow installation of approved roll bar, seat, intercooler or engine swap.
Unlimited: Must retain contiguous tub between OEM subframe mounting points. Examples: Radiator support may be removed or replaced. Cage may extend to shock front shock towers. Windshield frame may be removed.
Street must use unmodified OEM subframe unless part of non-Miata engine swap. May update/ backdate.
Mod & Unlimited – Free
All cars must retain functioning tail lights of same light output and color
Street and mod must retain OEM or direct OEM replacement taillights in original locations. Third high mount light may be removed.
Unlimited - Type and shape of tail light free and must be located within perimeter of OEM tail light
“Front” of the car is herein defined as the top of the windshield header forward
“Rear” of the car is herein defined as the top of the windshield header aft
Front or rear lip spoiler herein defined as “Homologated” i.e. that which is/was serial produced, is/was readily available to the public.
Rear lip spoiler may not protrude more than 7” above lower most point of OEM trunk lid. Taller than that and it will be considered a wing.
“Custom” is herein defined as not Homologated i.e. not for sale, not advertised, not readily available to the public, DIY, one of a kind or home made.
Lowermost point of front bumper skin to front subframe cross member- Free all classes
Mid-body Flat Bottom Under Tray herein defined as any structure covering more than 300 square inches combined of underbody between engine/transmission junction and rear axle centerline
Side skirts attached below door opening, between wheel openings- Free all classes
Any under body structure or structure (other than engine exhaust) covering more than 300 square inches combined of area aft of rear axle centerline herein defined as a diffuser.
201 or higher treadwear +0
200 or less treadwear +2
140 or less treadwear +4
100 or less treadwear +6
40 or less treadwear (also non DOT slicks) +8
Wheel width <7.5" +0
Wheel width 7.5-8” +1
Wheel width >=8.5" +2
Steel wheels -1
Any change to OEM front and/or rear sway bar (Update/ Backdate free) +.5
Any non OEM springs (not including threaded sleeves or adjustable spring perches) +.5
Any eccentric/offset front suspension pivot bushing (Street only) +.5
Any coilover, includes sway bar, bushing and spring points +2
Any aluminum brake caliper +.25
Non OEM header and/or test pipe +.5
Any internal engine mod (Cam, pistons, porting, etc) including 1-6~1.8, early 1.8 to later 1.8 swap +1.5
Any external engine mod (intake, ECU, pulley) +.5
Iron block: V8, V6, non Miata I4 swap +3
Aluminum block swap: V8, V6, Rotary, I4 +5
Forced induction (Miata engine) +5
Quaife or OS Giken dog box conversions +1
Any Torsen (including OE) or clutch type differential +1
Body / Aerodynamics:
Any Aftermarket front lip spoiler +.5
Any Custom front aerodynamic modification, including canard, splitter or bumper swap (includes lip spoiler) +1
Any Aftermarket rear trunk lip spoiler +.5
Any Custom rear aerodynamic modification, including wing, diffuser, bumper (includes lip spoiler) +1
Any non OEM lightweight body panels including non OEM hard top +1
Mid-body flat bottom under tray +.25
Approved driver seat and 5 or 6 pt harness and charged fire extinguisher installed -.5
Mod Class Lightening
Removal of headlight assembly +.25
Removal of front and/or rear bumper supports +.25
Any tubular control arm +.25
Removal of door windows and/or gutted doors +.25
.187” or .250” Lexan, Tuffak or Makrolon polycarbonate windshield +.5
NB/NC 99-11 +1 (applies to Street class only)
Excessive Rice +1
Non male -1
Automatic Trans (Miata engine only) -1
Rental Miata/MX5 (with rental contract) -1
Entrants will be required to have a completed entry form in the hands of the timing person before competition begins. It is the responsibility of the entrant to make sure this happens. Verbal requests to enter competition will not be counted.
Only officially registered AMB transponders recorded by Speedventures will be scored. You may rent one from SV or register your own on your entry form.
Entrants will be required to submit one vehicle for the day’s competition no later than 8:30 am that day. A tech sticker will be given to the entrant to be placed on the upper left hand (drivers) corner of the windshield. Entrants will not be allowed to switch cars once timed runs have begun.
Entrants found modifying their cars during timed sessions to a class above that which they are registered for will be disqualified and their points from the previous event deleted. They will also be banned from participating in the two subsequent MC events.
- All points scored will count towards series championship
- To be declared a class champion, the competitor must have won at least one road course event when there was a minimum of one other entrant in that class. In the event that the high points scorer did not win an event this way, the next highest point scorer will be declared champion
- In the event of a season final tie in points, the competitor with the most road course wins will be declared the higher points scorer.
- In the event of a season final tie in points and road course wins, the competitor with the highest average points per event (AX and RC) will be declared the higher points scorer.
- In the event we still have a tie, the faster of the two that day wins.
1st: 10 points
1st: 5 points