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CANAM
A sports car design with fully enclosed bodies, looking somewhat like GT cars. As the name suggests, this formula started in north america, and featured a centrally mounted seat and massive V8 engines. This types
of racing lost popularity toward the middle of the seventies.
CLUBMAN CARS See example
Two seater,
closed in wheeled cars with a live (beam) rear axle and steel spaceframe chassis. Engines were restricted to British Ford or
British Leyland pushrod types of 1000 to 1600cc. Four forward speed gearboxes were the only type allowed, and aerodynamic devices,
such as rear wings, legal. Wheels and tyres were racing items. Races were sub-divided into two classes: 1000cc to 1600cc fully
tuned cars and 1600cc Formula Ford engined cars.
FORD ESCORT MEXICO
A one-make series for
production Escort Mexicos (based on the Mexico rally winning car). All cars had the same 1598cc engines. (sometimes rated as
1601cc for homologation purposes) Very little, other than safety, modifications were allowed.
FORD ESCORT SPORTS
A one-make series for production Escort Sports.
All cars had the same 1300cc engines. Very little, other than safety, modifications were allowed.
FORMULA
ATLANTIC / FORMULA B (USA)
Single seater, open wheeled cars with mid-engined aluminium monocoque chassis.
Engines could be any 4-cylinder unit of 1100cc to 1600cc; the most successful
being the 1600cc Ford Cosworth BDA (Belt Driven A series). Alloy wheels
and racing tyres were used but were restricted to a maximum width. Formula Atlantic arose from the American Formula B and was devised as a transatlantic formula
to be raced throughout Europe
and the Americas.
FORMULA
FORD See
example
Single seater, open wheeled cars with mid-engined, steel spaceframe chassis. Engines
were restricted to Ford "Kent" 1600cc pushrod units from the Escort Mexico.
Four forward gears were allowed, limited slip differentials were banned,
and the drive had to be through the rear wheels. Wheels had to be 5.5 inch
wide steel road production units fitted with standard road tyres. These
'first step' cars were not allowed aerodynamic devices.
FORMULA
LIBRE See
example
Libre
being French for free describes this class well; all single seaters, Clubman
and Sports GTs could race in this formula. These races were sub-divided
into: Formula Ford Engined Cars, Cars up to 1600cc and cars over 1600cc.
FORMULA
VEE
Started in 1959, Formula Vee was the world’s most popular single seater racing of the time.
These cars were based on the Volkswagen Type 1 components: 1300cc engine, gearbox and torsion bar suspension units. Strict weight
and size limits applied to the chassis which could be of spaceframe or monocoque design. Engines had to be 1300cc or less, and
bore and stroke were specified. Although tuning was limited, restrictions on carburettor type and size restricted outputs to about
75bhp. Brakes and gearboxes had to be Volkswagen and wheels had to be 15 inch diameter and 5.5 inches wide. This formula was
seen as a cheap starting point for new drivers but not was not as popular in the UK as other countries.
FORMULA ONE See example
Single seater, open wheeled cars with mid-engined aluminium monocoque chassis.
Engines could be any unit up to 12 cylinders, super/turbocharged engines
were restricted to 1500cc and normally aspirated could be 3000cc. The most
successful F1 engine being the 3000cc Ford Cosworth DFV (Double Four Valve).
Gas turbine engines were allowed until 1979. Alloy wheels and racing tyres
were used but there was very little restriction to their width. This formula
came into being in 1966 and followed on from Grand Prix racing. Formula
One races were never held at Croft but a few F1 cars were raced in Formula Libre.
FORMULA
TWO See
example
Single seater, open wheeled cars with mid-engined aluminium monocoque chassis.
Engine blocks and cylinder heads could be from any production car of
which more than 1000 were made. Extensive tuning was allowed to the 2000cc
engines, and gearboxes were limited to five forward gears driving through
one pair of wheels. Alloy wheels and racing tyre were used but they were
restricted in width. This formula was seen as the final step to F1
at the time. Formula Two races never took place at Croft but many F2 cars
raced in Formula Libre.
FORMULA THREE
Single seater, open wheeled cars with
mid-engined, aluminium monocoque chassis.
Engine blocks and cylinder heads could be from any production car of
which more than 5000 were made. Extensive tuning was allowed to the 2000cc
engines but airflow was restricted by a 24mm diameter throttle flange.
Alloy wheels up to 25.4cm wide and racing tyres with a 20cm of tread were
allowed.
FORMULA
FOUR See
example
Started as a Formula for
motorcycle engined cars but took until the early seventies and a change to the F3 regulations (engines moved from1000cc to 1600cc)
for it to become popular. The chassis design was reasonably free from restriction, it having to be a rear engined, single seater type. A
1000cc engine from a British manufactured car homologated in Group 1 had to be used. Carburation was free for BL and Imp engines
but a 36mm or 40mm diameter restrictor was compulsory for Ford engine with down draught or side draught carbs. Alloy wheels and
racing tyre were used but they were restricted to narrow widths. No limited slip or torque bias differentials were allowed. Most
of the cars taking part in this formula were old F3 cars but cars such as the Delta IRF4 were specially built.
FORMULA
750 See
example
A formula devised, and strictly monitored, by the F750 motor club to maintain low cost racing. Originally
designed to run Austin Seven chassises and engines, the first F750 race took place in 1950. Design rules stated the car had to be
a two seater with closed in wheels, a live rear axle and a steel spaceframe chassis. Incorporated into the chassis design had to be two 2
inch (5cm) square side rails to reflect the design of the Austin Seven chassis originally used. By the 1970s, these cars had specially
built chassises and the much more readily available Reliant engines were used. Restricted tuning of the 750cc engine was allowed,
and no more than four forward gears were acceptable. Formula 750 races are still held today and there have been very few rule
changes in the mean time.
FORMULA
1300 See example
A formula devised, and strictly monitored, by the F750 motor club to maintain low cost racing. It
was run as Formula 1200 from 1951 to 1973 where, at first, Ford side valve engine of 1172cc were used until they became too scares
and the Anglia 1200cc units took over. When the Anglia engines became expensive to tune, the much cheaper 1300cc Ford units were
allowed and the Formula changed its name to reflect this. They were two seater, closed in wheeled cars with front or rear engines.
Chassis could be spacefame of monocoque and suspension was free. Engines were at first restricted to Ford 1300cc, later, Cosworth
BDAs could be used.
FORMULA
5000 See
example
Single seater, open wheeled cars with mid-engined aluminium monococque chassis.
Similar regs to that of Formula One applied but engine were the much cheaper
5000cc V8. Sometimes, joint races between F1 and F5000, such as the British
Champion of Champions, were held at the end of the season at Grand Prix
circuits. Formula
5000 cars were a popular choice for Formula Libre with some internationally
known drivers turning up for these races.
GROUP
ONE (SALOONS) See example
Raced
at national and international level; these cars were closely based on production
saloons but had numerous 'added extras' which greatly enhanced performance.
Most top manufacturers had their own teams and were heavily involved in
development work.
GROUP
TWO (SALOONS)
Raced at international level; these cars were full race versions of production saloons. Most top manufacturers had their own
teams and were heavily involved in development work. Outrageous development cost killed off this formula. Group Two Saloons races
never took place at Croft but some raced in Special Saloons.
GROUP THREE (Sports cars) See example
example
Roughly equivalent to Group 1 Saloons, these cars were produced in large numbers and raced in standard trim.
GROUP FOUR (Sports Cars) See example
Roughly equivalent to Group Two Saloons, these cars were produced in smaller numbers and highly modified.
GROUP FIVE (Saloons and Sports Cars)
Based on production cars, they had highly modified engines and bodywork but had to retain some production parts such as the engine block.
GROUP SIX See example
Two-seater racing cars which shared more similarities with single-seaters than production sports cars.
GROUP EIGHT See example
This was the name given to the British Aurora F1 championship when it raced both F1 and F2 cars.
HISTORIC SPORTS CARS See example
This
class was open to all types of older sports cars from one-offs to production
models. A mixture of Jaguars, Elvas, Lotuses and other exotic makes could
race in one championship series, or separate championships for one make
could be run.
MINI
MIGLIA
A
formula devised, and strictly monitored, by the F750 motor club to maintain
low cost racing. These cars were bases on standard Minis and were allowed
a little more tuning to their 1000cc engines and suspension than were Mini
7 racers.
Present day rules allow1300cc 'A' series engines, Dunlop racing slicks, brakes must have a maximum of four pot calipers and the suspension may be upgraded to dual gas shox.
MINI
7
A
formula devised, and strictly monitored, by the F750 motor club to maintain
low cost racing. These cars were bases on the first Mini 7s and were allowed
limited tuning to their 850cc engines and suspension.
Present day rules allow1000cc 'A' series engines, Dunlop Racing Tyres, brakes must be made up of standard Cooper S components and the suspension may be upgraded but not changed.
MINI
1275 GT
A
one make series for production Mini 1300cc GTs. Little modification was
allowed other than for safety.
MODIFIED
SPORTS CARS See
example
These
were, as the name suggests, modified road-going cars, the class being re-named in 1970 from Prodsports (not to be confused with
Production Sports Cars of the 70's). Prodsports had similar rule to Special Saloons up until then and fiberglass replicas were
being used; along with this name change came changes to the rules to bring the cars nearer to their original specifications.
Engines had to be a one originally supplied with the car but there were no restriction to tuning as long as the main engine
components were not substituted for special items. Suspensions had to retain the original set-up and components but leaf spring
could be changed for coil springs, and lever arm shock absorbers replaced by telescopic. Parts could be added to the suspension to
improve location. Brakes were free from restrictions. The bodywork had to retain the original material, no lightweight replicas
were allowed, but some lightweight panels were permissible as were wheel arches, lightening/airflow holes and spoilers. Cars were raced against others of
similar engine capacity, which were bases on Le Mans/GT classes - hence
the strange up to 1150cc class.
Classes:
A
- over 2001cc
B
- 1501cc to 2000cc
C
- 1151 to 1500cc
D
- up to 1150cc
MONOPOSTO
See example
Single seater, open-wheel single seaters with engine
mounted at the front or rear. Chassis design could be of any type and be of one-off construction or a propriety built car older than 4 years. Engines had to
pushrod and have a maximum capacity of 1600cc. Carburation was free but
forced induction was not allowed. This was a popular formula which sometimes visited Croft, but mostly these cars took part in the
Formula Libre races.
PRODUCTION SALOON CARS See example
A
formula for current, at the time, road going saloon cars which had the
required production run. Only safety modifications were allowed. Classes
were based on price.
1975
classes:
A
- over £2300
B
- £1700 to £2299
C
- £1300 to £1699
D - up to £1299
SPORTS CARS (Group 3) See
example
A British formula, based on the FIA
Group 3 regulations, for current, at the time, road going sports cars which had the
required production run. Only safety modifications were allowed. Classes
were based on price and an upper limit of £4000 was imposed to stop
exotic supercars running away with the prizes.
1975
classes:
A
- £2250 to £ 4000
B
- £1400 to £2250
C
- up to £1400
RENAULT 5 See example
A one-make series for production Renault
5s. Little modification was allowed to these 956cc cars other than for safety. Probably the slowest formula to race in the
seventies; these cars had poor performance and leaned at frightening angles when cornering.
SPECIAL
SALOONS See example
These were modified road saloon cars ranging from home tuned 850cc
budget racers to eight litre, no expense spared, Super Saloons. Special
Saloons ran five classes: class 'E' was smallest class allowing engines
up to 850cc and was the hunting ground of mostly Minis and Imps; class
'D' cars had engine capacities from 851cc to 1000cc; class "C"
were cars of 1001 to 1300cc, again Minis dominated but Ford Anglias and
Escorts (an Escort BDA held the lap record) were also competitive;
class 'B', 1300cc to 2500cc, allowed a wide range of saloons to take
advantage of Ford and Vauxhall based racing engines and V8 engines
dominated the big class,' A', of over 2500cc; these being shoehorned
into some of the most sophisticated racing cars of the time.
SUPER
SALOONS (and later - SUPERLOONS) See example
A formula devised for the most sophisticated of the Special Saloons.
Cars had to be based on a saloon (sedan) car, the choice of engine was
free but they had to be over 1599cc and remain in the same position as
the originals. Any type of gearbox could be used. Constructors
interpreted the few regulations freely and rear engined cars such as
Skodas and VWs suddenly became mid-engined, just like single-seaters.
The silhouette of the car above the centreline of the wheels could not
be changed but super-light bodies, spoiler, air dams, splitters and
power bulges were allowed. The ingenuity of the builders knew no bounds
and these £10,000 + machines were no more than prototype sport racer
chassis with F1, F2, and F5000 engines, covered by fibreglass replica
saloon bodies. |
