Group ND Proposal

Mudguard flares and/or bolt-on extensions are free save that:

• They must be approximately semi-circular and bolted/screwed to the bodywork as per PERIOD (not welded/bonded) and not be “flared or boxed bodywork”
• Where they were factory fitted or factory optional to the MODEL in the PERIOD, they should emulate that shape, size and design as seen in PERIOD competition cars
• They must not prevent any rear door from functioning as intended and thus may include a separate door component.

Adjacent modified bodywork must be rendered safe by welding  or otherwise bonding the metal panels

Justification and Rationale

Flares were permitted and utilized in Australian Group C and FIA group 2

Various manufacturers offered them as standard equipment or option on certain MODELS in the period, eg, Holden Gemini CDT sedan and coupe, Holden LH/LX Torana, Toyota Celica Supra, Mini Clubman & GT

Giving all competitors the option, takes away any real or perceived performance improvement.

Other proposed rules will limit wheel track increases so there cannot be “stupidly wide” flares that are out of context with the PERIOD appearance

Mandating bolt-on flares is an approach to contain costs and matches PERIOD race appearance, especially in Australia (e GpC)

Group ND Proposal

Engine Block and related

The engine block may be original for the model or changed to a later casting/version from the same manufacturer of the vehicle model, provided it :-

• Is made from the same type of material, eg Aluminium alloy or cast iron
• Has identical cylinder bore, crank stroke and crankshaft tunnel sizes
• Has identical main cap fixtures and locations
• Has identical cylinder head fixtures and locations
• Accepts the original camshaft drive system, oil pump, ignition distributor (if fitted to the block)
• Accepts identical engine mounting and support brackets
• Has the same engine model code allocated by the manufacturer

All rotating and reciprocating parts inside the engine block are free save that the crankshaft stroke cannot be altered

The engine mechanical water pump and its drive system is free . Cooling system hoses are free .

Balancing, coating, polishing, surface refinishing , electroplating and heat treatment of any internal component is free.

The block must not be externally altered by grinding off unwanted segments, brackets, manufacturer Identification marks etc.

Cylinder Head

The cylinder head may be a later casting/version from the same manufacturer or a more modern reproduction or performance oriented alternative that may have different size or shape ports. 

Where a non original head is adopted,  the intake and exhaust port numbers , general location (ie, on which side of the head), number of head studs/bolts and any cam shaft drive system must not change from that which was original for the MODEL.

All rotating and reciprocating parts inside the cylinder head are free.

Fixed devices located under the valve or rocker covers ,such as rocker support posts, are free.

Emission control devices such as EGR valves, are free.

Valve Actuation

Any valve operation system may be freely modified to allow adjustment of the static timing, however the basic method of operation must not change, eg chain drive cannot be swapped for belt drive or gear drive or vice-versa. Belts, chains and tensioning devices are otherwise free.

Valves, valve springs,  rocker arms , rocker pedestals , cam buckets , retaining collets and any related packers or shim, are free . Any variable cam timing or valve lift system is free.

Justification and Rationale

The combination of Group N general requirements + this Nc section are seen as too proscriptive and detrimental to wider competitor uptake, especially for a newer cohort or racers with a new generation of more complex vehicles.

Many of the period MODEL have a vast range of competition parts already available off the shelf

The suggested new Nd rules are more complex because the cars and engines of Nd era are more complex with widespread introduction of multiple overhead cams, electronic injection, turbocharging etc and the nature of modifications commonly seen on Nd era cars. A balance has been sought between trying to stay largely “original”  (which can drive up costs) and  having extensive freedoms to swap engines akin to Sports Sedans  or even 3J IP .

Group ND Proposal

The ignition system is free save that the number of ignition coils being used cannot change.

Note: A wasted spark coil assembly or a 2-outlet , 1-piece coil, will be treated as a single coil.

Justification and Rationale

This provides sufficient freedom for cars with both EFI and carburettors and levels the playing field somewhat.

Limiting the number of ignition coils will potentially only effect highly modified forced induction engines and prevent a move to more modern coil-on-plug systems which , whilst common in performance road car modifications, will be visually and obviously incorrect for the PERIOD.

Group ND Proposal

The transmission, clutch, flywheel and any mountings are free save that:

• Any replacement transmission is from a production MODEL, but ratio changes are OK provided the gears retain a helical tooth pattern.
• The transmission retains the same number of forward gear ratios as the model.
• It retains a H pattern manual shifter located in the MODEL location and trimmed/finished as per MODEL
• Dog engagement of gears (non syncro) is not permitted.
• No form of automation of the shifter system or clutch operation is permitted.

Any changes to the bodywork to accommodate a replacement transmission must be neatly finished so the interior appearance is unchanged.

Justification and Rationale

These freedoms will collectively maintain the lowest possible cost of competition by preventing race-only dog boxes and/or sequential shifters being adopted.

Insisting on an unchanged interior appearance helps to maintain a PERIOD appearance whilst still allowing for transmission changes.

Group ND Proposal

The final drive assembly is free save that:

Any replacement assembly cannot widen the wheel drive flange to flange width more than 40mm.

The body work including pick up points for the final drive, remains unchanged.

Justification and Rationale

Being able to alter the final drive assembly allows competitors to utilize readily available and relatively lower cost components, eg using the common HILUX diff for which there are a plethora or race-suitable ratios and LSD or locking units.

MODELS with particularly fragile final drives can be upgraded to better manage costs.

Note: ND vehicle can be RWD live axle, RWD IRS, AWD, FWD.

Group ND Proposal

These items are free save that no in cabin adjustment can be possible:

• Springs
• Torsion bars
• Sway or roll bars
• Shock absorbers (dampers), save that their connection points to the body work may not be moved
• Wishbone and linkage rods, arms and their pivoting end “bushes”

Wishbone and/or control arm connection points on body structure or any bolt-in subframe, may be moved by up to 30mm.

Each fully sprung part of the Automobile, except for the exhaust system, must be at least 100mm above the ground when measured at a point within the wheelbases. The Automobile ride height shall be measured with the driver, and all normal necessary equipment fitted.

Justification and Rationale

Permits simple and cheap adoption of off-the shelf components now commonly found on both road going and race cars of the PERIOD.

Enclosed spherical joints were becoming common place in suspension components on a wide variety of cars (eg Triumph Dolomite, Toyota Corolla) , so forcing the use of elastomeric bushes is unnecessary and could result in a perceived performance difference between MODELS.

The freedom to move pivot point locations allows for commonly seen “race” modification on lots of MODELS.

Group ND Proposal

Braking system must remain as original ie Drum-Drum, Disc-Drum or Disc-Disc

All brake components are free save that:

• Where disc calipers are used, there can be only 1 per wheel and they cannot be liquid cooled.
• Brake calipers must be of PERIOD external appearance and have no more than 4 pistons per caliper
• Brake drums must be ferrous but finned alloy cooling rings may be pressed onto them.

Note: The size of the disk or drum assembly that can be used will be limited by the rim size. 

Justification and Rationale

In this PERIOD, braking systems became much more complex with the advent of dual circuit master cylinders, ABS and 4-wheel discs and this can make repair and/or modification complicated.

In some cases, an ABS system cannot be effectively modified for competition use and/or its control devices repaired.

Allowing this freedom improves safety by allowing competitors to choose the best system that will fit under the wheels

Retaining a period appearance for calipers will not adversely impact the overall look of the vehicle.

Group ND Proposal

Wheels maybe increased in diameter by 2 inches

Wheel design and construction must be compatible with the PERIOD save that magnesium construction and/or centre lock single nut arrangements are prohibited

Maximum permitted rim width:

• Class A and B Maximum 8 inches
• Class C, D and E Maximum 7 inches
• Class F and G Maximum 6 inches

Wheel nave plates or covers must be removed

Any wheel to hub spacers used must be securely fitted, not slip on

Vehicle Classes

Justification and Rationale

Simplification in line with ever increasing size of wheels found on production cars in the PERIOD

The prohibition on magnesium and centre lock wheel is to cap costs and increase safety in an amateur sport.

Note: Allowing a maximum of 2 Inch increase will permit drivers to upsize to a rim/tyre combination where race tyres are available, 14" and 16" rims are common on ND era cars and race tyres are already obsolete for most common brands.

Group ND Proposal

Tyres must be correct for the wheel width and diameter as determined by the Tyre and Rim Association Handbook

Tyres must be selected from the Production car tyre list

Justification and Rationale

Expanding the tyre choice and not proscribing 60% aspect ratio will enable more suitable tyres to be chosen when a competitor wishes to increase the rim diameter as per other rules/freedoms.

Group ND Proposal

1. Supercharging is not permitted unless fitted as standard to the particular model.  
2. The supercharger general location and its drive system must remain unchanged.
3. The brand of supercharger is free save that the type of supercharger must be maintained (e.g. Roots, Twin Screw, Centrifugal, Sliding vane etc.)
4. For any replacement supercharger , the per cycle flow of the supercharger can be no more than 40% greater than the standard vehicle supercharger.
5. Boost pressure and all other associated components including pulleys, intercooler/s and boost controller/s are free, however any intercooler pipes must only be used to channel air and no external bodywork alterations are made to accommodate the supercharger, intercooler and its pipes. Any holes drilled in inner panels for intercooler pipes must be no larger than needed for the pipe and fitted with a rubber or similar sleeve.
6. Water or alcohol injection is prohibited.
7. Water cooling of intercoolers is prohibited.

Justification and Rationale

Similar to the current Group 2B regulations.

Group ND Proposal

1. Turbo charging is not permitted unless fitted as standard to the model.
2. Turbocharger/s and associated inlet and exhaust manifold/s are free provided the compressor housing inlet diameter is no larger than the original standard turbocharger compressor wheel inducer diameter plus 10%.
3. Twin turbochargers may be replaced by a single turbocharger configuration with an inlet cross sectional area no greater than the combined inlet cross sectional area of the standard twin turbochargers.
4. Measurements for the compressor housing inlet diameter and cross sectional area shall be taken at the narrowest point of the inlet - within 1mm of the outermost face of the compressor wheel vane.
5. The original turbocharger general location on the manifold (eg top or bottom mount) must remain.
6. All other associated components including intercooler/s and boost controller/s are free, however each intercooler pipe (both to and from the intercooler) must only be used to channel air and no external bodywork alterations are made to accommodate the intercooler and its pipes. Any holes drilled in inner panels for intercooler pipes must be no larger than needed for the pipe and fitted with a rubber or similar sleeve.
7. Water or alcohol injection is prohibited.
8. Water cooling of intercoolers is prohibited.

Justification and Rationale

Similar to the current Group 2B regulations. This is a more sensible approach as repairs to, or replacement of, ND era turbo’s is near impossible.

Most ND era cars that are turbo charged have an inducer diameter much larger than the old MSA restrictor system.

Group ND Proposal

Mandatory removal of self-locking door latches

Mandatory removal of alarms and immobilizers

Mandatory removal of steering locks

Justification and Rationale

These are all common sense safety requirements

Group ND Proposal

The radiator may be replaced but must retain its original location, form and function.

The support panel opening may not be modified except for mounting bolt locations.

The material from which the radiator may be manufactured is free.

Any attached fans or shrouds are free

The control system for any electric fan is free

Justification and Rationale

Allows commonly seen alloy radiators and electric fans to be easily added without disagreements

Freedom with electric fan controllers will allow competitors to choose to use off-the-shelf simple controls or make it a function of either factory or aftermarket ECU

Group ND Proposal

The original lubrication system supplied by the manufacturer must be employed, save that oil pumps may be replaced or modified to enable higher pressure and/or volume, and additional external oil lines to original or approved components may also be employed. Any replacement oil pump must work on the manufacturer's original principle. Sumps as supplied as original equipment for the model in question may be modified to incorporate baffles and/or increased capacity. Oil coolers and remote oil filters are permitted, but the external bodywork must not be altered for the purpose of fitment, nor may they be fitted outside the confines of the standard bodywork. Dry sump lubrication systems are not permitted, unless originally fitted. Remote pressurised oil accumulators are permitted, conditional on them being used in conjunction with a normal wet-sump oil system and serving no other purpose. The capacity of the accumulator must not exceed three litres. Should the accumulator be mounted in the cockpit then the system must comply with the Manual Technical Appendix Schedule A (I)

Any holes drilled in inner panels for Oil Cooling pipes must be no larger than needed for the pipe and fitted with a rubber or similar sleeve

Justification and Rationale

Trivial change to clarify how oil coolers can be “plumbed” and allowing for holes to be made in internal panels to route hoses.

Group ND Proposal

The Fuel delivery system type must remain as per the manufactures specifications in the Vehicle Specifications eg:

• Carburetted
• Mechanical Fuel Injection
• Electronic Fuel injection

Note: For both mechanical and electronic fuel injected cars there can be no more than 1 fuel injector per cylinder or rotor.

Throttle Plates

On a carburetted car the original carburettor may be swapped for a different carburettor or replaced with multiple carburettors. The inlet manifold is free.

On fuel injected cars the number of throttle bodies is free as is the inlet manifold.

The total number of throttle plates can be no more than the number of engine cylinders or rotors.

Fuel Regulation

Fuel pumps and fuel pressure regulation is all free.

On Carburetted cars, elements that control the fuel regulation such as jets, vacuum units, springs and electro-mechanical mechanisms are all free.

On Mechanical Fuel injected cars, elements that control the fuel regulation such as metering units, distributing units, vacuum units, springs, air flow devices and other mechanical mechanisms are all free. The size of the fuel Injectors is free.

On Electronic Fuel injection cars, elements that control the fuel regulation such as the ECU, sensors and pickups used to provide the ECU with engine data are all free. The number of sensors and pickups used is also free. The size of the fuel Injectors is free.

Justification and Rationale

As other historic classes have permitted quite radical changes to carburetted vehicles. The same freedoms have been translated into both Mechanical Fuel Injection and Electronic Fuel Injection systems that are used on a lot of Group ND era cars.