Number of posts : 16788
Age : 120
Location : International Simracing Organisation
Registration date : 2010-09-17
|Subject: Re: Important Q for you all regarding set-ups Sat 23 Oct 2010 - 18:15|| |
OK, it's decided then
In case any of you is interested in the reading, here are the FIA Group 4 rules until 1981: (Note that Procars had some slight limitations introduced by BMW for their own series like f.e. differential slip fixed at 40%)
- Quote :
- GROUP 4 RULES UNTIL 1981:
Modifications authorised : Exactly the same as those authorised
for Group 2 (Special Touring Cars) (see Art 261), with the exception of the
following scale of weights (Art 255 h). These weights are weights such as the
car crosses the finishing line, weight of the fuel deducted.
Up to 500 cc: 495 kg
,, ,, 600 cc: 535 kg
,, ,, 700 cc: 570 kg
,, ,, 850 cc: 615 kg
,, ,, 1,000 cc: 655 kg
,, ,, 1,150 cc: 670 kg
,, ,, 1,300 cc: 700 kg
,, ,, 1,600 cc: 740 kg
,, ,, 2,000 cc: 810 kg
,, ,, 2,500 cc: 880 kg
,, ,, 3,000 cc: 945 kg
,, ,, 3,500 cc: 1,005 kg
,, ,, 4,000 cc: 1,075 kg
,. ,, 4,500 cc: 1,120 kg
., ,, 5,000 cc: 1,170 kg
,, ,, 5,500 cc: 1,225 kg
,, ,, 6,000 cc: 1,270 kg
,, ,, 6,500 cc : 1,310 kg
, ,, 7,000 cc: 1,340 kg
,, ,, 7,500 cc: 1,365 kg
,, ,, 8,000 cc: 1,380 kg
Over 8,000 cc: 1,465 kg
b) Modifications of the original mechanical parts: The original mechanical
parts having undergone all the normal machining operations foreseen by the
manufacturer for series-production, except those for which the present article
provides a freedom of replacement, may be subject of all perfecting operations
by means of finishing or machining, but not replacement. In other words, provided
the origin of the series-production part may always be ascertained undoubtedly,
this part may be rectified, balanced, lightened, reduced or modified
in its shape through machining. This permission however does not apply to
brake callipers. Any adjunction of material in an homogeneous way (welding,
gluing, electrolysis) is forbidden for the following mechanical elements: engine,
gear-box, transmission, suspension parts.
c) Engine - cylinder-heads and valves: Besides the modifications which
can be carried out on the cylinder-head as specified under paragraph b) hereabove,
complete freedom is left as regards valves, valve-guides and valve-seats.
The number of valves per cylinder cannot be modified. It is allowed to add
washers to the valve-spring assembly.
Valve-springs are submitted to no restriction as regards their number and type,
provided the modifications remain within the limits provided for in b).
cl) Engine-induction system and elements: Free. However, supercharging
will be forbidden if nct recognised.
Aft 259-60-61 : Group 2
e) Engine-reboring : No overlapping of cylinder-capacity class is allowed
(Art 252 i). A 0.6 mm maximum reboring is permitted. It is permitted to sleeve
(or re-sleeve) the engine within the aut!?orisec! dimensions.
By sleeve, it will be understood the metal cylinder inside which the piston
moves. This part will be a separate component which will be fitted in the block
in different ways: pressed, welded, etc.
The material will be free. In case the engine would be directly bored and no
intermediate part used, it will be possible to add a sleeve, the material of which
will be free. An addition of material will be permitted inside the cylinders.
f) Engine-exhaust system and elements: Free. The piping will however be
conceived in such a way as to end on one of the sides or at the rear of the car.
However, for all types of events, organisers may provide for a particular restriction,
which will be mentioned in the regulations of the event. Besides, for
events run on open roads, the efficiency of the mufflers must conform to the
legal prescriptions of the country where the event is run.
g) Engine-bearings: Plain, or roller bearings may be replaced by others of
the same type.
h) Engine-gaskets: Gaskets may be repiaced by others or suppressed.
modified provided its original body is retained.
The number of oil pumps originally fitted cannot be changed.
A dry sump lubrication system is forbidden, unless recognised in series.
Oil filters and oil coolers are free (type, number and capacity). The fitting of
an oil cooler exterior fro the coachwork is only permitted be!ow the horizontal
plane passing through the centre of the wheel-hubs. In no case, such a fitting
of an oil cooler map result in the addition of an aerodynamic enveloping structure.
Moreover, the oil cooler must not constitute a protuberance outside the general
car perimeter, seen from above, such as presented on the starting line.
j) Engine-camshafts and valve gear: Free. Yet, the location, number and
driving system of the camshaft (S) cannot be changed (chain, belt, gears, conrods,
k) Engine-piston, piston axle and piston rings: Free.
I) Engine-other elements: Mobntings are free. The cooling fan and waterpump
may be modified, replaced or suppressed.
There is no restriction for the fuel pump as regards number, type, location and
output. Nevertheless, it must never be located in the passengers' compartment.
The inclination and the position of the engine inside the engine compartment
are free, provided however the implied modifications do not go beyond what is
allowed in Art 261 b, I, m and n.
m) Transmission : For one same series ~f 1,000 cars, the following possibilities
are given on the express condition that they are those of the series-production,
and that they are normally sold to the purchaser and entered on the recognition
Gear-box: Three sets of recognis~dra tios, which may be mixed, on condition
that the gears are not combined into a one piece gear unit. The number of ratios
of the gear-box(es) of origin must be retained. The synchronisation system of
origin must be retained.
Selection forks may be reinforced by addition of material, by way of exception
to Art 261 b).
Mountings are free. The location and type of the gear lever are free. The gearbox
casing should remain that of origin, within the limits of the modifications
permitted in paragraph b). The original principle of lubrication of the box should
be retained; however a cooling device for the gear-box oil is authorised (circulation
pump and radiator).
For cars fitted with automatic gear-box, a completefreedom is left for the ratios
on condition that their number is unchanged. The torque converter is free.
DiRerentlal: Mountings are free. The differential ratios are free, provided
however it is recognised. No minimum production is necessary for this recognition.
A limited-slip or self-blocking differential may be fitted but not with a constant
and complete blocking effect, provided it can be located in the casing without
entailing a modification beyond that allowed under paragraph b). All the
transmission shafts and joints between the engine and the wheels are free.
The original principle of lubrication must be retained; however a cooling device
for the oil is authorised (circulation pump and radiator). A complete freedom is
left as regards pulleys and belts for belt transmissions.
Clutch: The clutch will be free on condition that it has the same number of
discs as the series-production clutch and that the original bell-housing and flywheel
n) Suspension: It is permitted to modify the original parts of the suspension
according to the specifications of Art 261 b). The addition or suppression of
an anti-sway bar is permitted.
The material and dimensions of the main spring are free, on condition that it
remains unique in the performance of its function.
The addition of auxiliary springs is permitted on condition that the main spring
of origin be retained unchanged.
The shock absorbers anchoring points may be reinforced.
The fitting of joints of a different type andlor material is authorised.
o) Steering: The steering ratio is free, provided that the original steering box
is kept. A servo steering system may be disconnected, or its recognition can be
granted without minimum production.
p) Wheels and tyres: Free, provided their fitting can be carried out in full
conformity with Art 255 d) and in so far as the complete wheel (Art 252 1) width
in relation to the cylinder-capacity of the car does not exceed the following
Up to 1,300 cc: 9"
,, ,, 1,600 cc: 10.5"
,, ,, 2,000 cc: 11.5"
,, ,, 3,000 cc: 13"
,, ,, 5,000 cc: 14"
,, ,, 6,000 cc: 15"
Over 6,000 cc: 16"
Moreover, the four wheels of a car must always have the same diameter (Art
252 1). The spare-wheel is not compulsory. Honrever, in case one should be installed,
i t must be firmly attached, not installed within the space reserved for the
driver and the front passenger, and not entail modifications in the outside aspect
of the coachwork.
Q) EIectricwl equipment-lighting equipment: Free. Yet for events on open
roads, the vehicle must be in compliance with the police regulations of the
country where she event is run or with the international convention c;n road
trafic (Art 255 k).
The liberty given for the lighting devices concerns their replacement or modification,
but does not allow their suppression.
Their number should be even. The minimum lighting equipment should remain
in normal functioning conditi~nsd uring the whole event. Two stop lights are
The lccation of the battery is free; however, it should not be placed in the
habitacle. In case the battery would be placed within the habitacle of a car in the
normal production, it may retain this location on condition it is properly protected.
E[ecfrical system-engine accessories: It is allowed to replace a dynamo
by an alternator and vice-versa. Its mounting brackets and crankshaft pulley are
free. The generator may be removed or put out of use. The ignition system is
free on ccnclitisn the modifications involved are authorised in Art 261 b). The
fitting of a dolible ignition system is not allowed, except if recognised with a
minimum production equa! to that of the basic homologation.
The make and type of the starter motor are free.
r) Fuel tanks and water radiators: The capacity of fuel tanks is limited by
Art 255 g).
In case the tank of origin would be changed, either the modification will be
made in conformity with Art 261 bb), or the fuel tank will be a safety fuel tank
recognised by the FI.4 (minimum specification FT3). Should the tank and its
fiiler be located in the luggage compartment, an outlet must be provided at the
lowest point for the fuel accidentally spilled in this compartment.
The location and dimensions of the fiiler orifice as weil as those of the filling
cap may be changed, provided the new fitting does not protrude beyond the
coachwork iine and provides against fuel leakage into the inside compartments
of the car.
There is complete freedom as regards the water radiator and its capacity. Its
location may be changed provided no modification is entailed either to the outside
or to the inside (habitacle) of the coachwork.
S) Braking equipment: The mounting of a double master-cylinder or of any
device which produces simultaneous action on the four wheels and a separate
action on two wheels at ieast is compulsory.
The discs may be replaced by others provided the area of the friction surface
is not modified; the same does apply to the drums.
It is however not permitted to replace drums by discs and vice versa.
Linings are free. The backing plates may be modified and fitted with air openings.
Protection shieids may be modified or suppressed. Cooling air-ducts may
be added provided they do not entail a modification of the coachwork.
Thn ~dditiono r the suppression of brake servos is allowed.
It is not permitted to modify the drum disc callipers which can only be replaced
by callipers recognised by the manufacturer without minimum production (re
Art 261 bb).
t) Cables and pipes: It is allowed to entirely modify the arrangement, location
and materiais of ali cables and pipes providing for the passage of fluid
e!emenls (air, water, fuel, eiectric currents, etc, including the suspension system).
The fuel and high temperature liquid pipes and air ducts should not pass
through the habitacle, except if this mounting is realised in series. In all cases,
these pipes should be efficiently protected.
U) Springs: Any spring, including its abutment(s), may be replaced by another
one of similar type (ie, leaf spring, coil-spring, etc) except in the case of the
suspension where Art 261 m) applies. Its original location must be retained.
v) Coachwork elements: The front seats may be replaced.
It is permitted to remove the rear seating arrangements, as well as the passenger
seat. However, when the rear seating arrangements are removed, cars shall
be fitted with a rigid metallic partition flame and liquid proof which will separate
the passengers' cornpartmefit from the engine compartment and fuel tank.
It will be forbidden to install anything except the fire extinguisher, and, according
to the case, the spare wheel inside the passengers' compartment.
The lightening and modification of the structural elements of the coachwork
or the chassis cif the car is forbidden. Any kind of reinforcement is authorised.
It is allowed to fit aerodynamic devices on the front part of the car below the
horizontal plane passing through the centre of the wheel-hubs. Nevertheless,
these aerodynamic devices shall not protrude beyond the overall perimeter of
the car, seen from above.
All recognised windows and winding mechanisms should be retained. The
original rear window should also be retained. Non-visible insulating material may
be removed. Trimmings of the passengers' compartment, of the door panels,
etc, which are normally providedforcarsoftheseries-production may belightened
but not removed. The original aspect of the inside must be kept. I t i s also permitted
to remove the glove-box and the floor carpets.
It is permitted to widen the wing by beating, within the limits foreseen by Art
261 cc) (wing extensions).
W) Heating system: It is permitted to remove the heating devices and their
accessories on condition that the demisting of the windshield and the rear
window remains assured, if provided in series.
X) Options-definitions: A variant of the series-production.
Accessories or equipment delivered on express request of the customer. By
option is therefore meant any equipment supplied in supplement to or in place of
the basic model available on request, even if this equipment is normally fitted
on scme series-production cars as is the case, for example, of cars for export.
aa) Recognition of an option: The recognition of an option will only be
granted if the optional equipment may be obtained without any discrimination
from the manufacturer or his concessionnaires by any person who wishes to buy
bb) Optional equipment which may be recognised without a minimum
- Reinforced suspension elements and rear axle, provided they are absolutely
interchangeable with the original part and that the pivoting points to the chassis
remain in their original location and that the kinematics of the suspension is not
- Different dashboard.
- Brakes-brake callipers.
- Fuei tanks. - Steering rods.
- Servo steering (Art 261 0).
- Underneath nrotections.
- Wing extensions (simple defleytors of at least 120" and of 5 cm maximum
width and 10 cm maximum height).
Front view Side view \1
dd) Any other option affecting directly or indirectly the performance of the
car cannot be recognised unless 1,000 identical cars equipped with this option
have been manufactured in 12 consecutive months.
In case this article would be applied within Group 4 (Special GT), the minimum
production would obviously be 400 cars and not 1,000 in 24 months.
NB: Mechanical elements recognised in Group 2 before 31.12.75 as well as the
authorised modifications according to the prescriptions of Art 260 of former
Appendix J can be used until 31.12.77 for rallies. The car will be automatically
transferred to Group 4.