Lotus Seven
Encyclopedia
The Lotus Seven is a small, simple, lightweight two-seater open-top sports car
produced by Lotus Cars
(initially called Lotus Engineering) between 1957 and 1972.
It was designed by Lotus founder Colin Chapman
and has been considered the embodiment of the Lotus philosophy of performance through low weight and simplicity. The original model was highly successful with more than 2,500 cars sold, due to its attraction as a road legal car that could be used for clubman racing
.
After Lotus ended production of the Seven, Caterham
bought the rights to it, and today make both kits and fully assembled cars based on the original design.
The Lotus Seven design has spawned a host of imitations on the kit car
market, generally called Sevens or sevenesque roadsters. Many of those cars are still produced to this day. Along with manufacturer supplied kits, there are entirely self-built sevenesque cars referred to as Locost
s.
was in limited production. The Seven name was left over from a model that was abandoned by Lotus, which would have been a Riley-engined single-seater that Lotus intended to enter into the Formula Two
in 1952 or 1953. However, the car was completed around Chapman's chassis as a sports car by its backers and christened the Clairmonte Special.
Based on Chapman's first series-produced Lotus Mark VI, the Seven was powered by a 40 bhp Ford
Side-valve 1,172 cc inline-four engine. It was mainly for lower budget club racing on short tracks (750 motor club).
The Lotus Seven Series 2 (S2) followed in 1960, and the Series 3 (S3) in 1968. In 1970, Lotus radically changed the shape of the car to create the slightly more conventional sized Series 4 (S4), with a squarer fibreglass shell replacing most of the aluminium bodywork. It also offered some "luxuries" as standard, such as an internal heater matrix. The S4 model was not widely welcomed, and Lotus sold few cars. What is believed to be the oldest of these Series 4's survives to this day, and can be seen most weekends around Sussex and Kent. A familiar face at Lotus events up and down the country, this was the second Series 4 ever built, and has proved critics of the S4 wrong; it's looks ageing better than many predicted, and its performance and reliability unsurpassed by any of the original Sevens.
The British tax system of the time (Purchase Tax) meant the car could be supplied as a kit (known as "completely knocked down" or CKD) without attracting the tax surcharge that would apply if sold in assembled form. Tax rules specified assembly instructions could not be included, but in a typical Chapman-inspired piece of lateral thinking, there was no rule covering the inclusion of disassembly instructions. Hence all the enthusiast had to do was to follow these in reverse.
Having joined the EEC on 1 January 1973, the UK had to abolish Purchase Tax and adopt VAT instead. VAT does not allow for concessions such as "CKD", so the tax advantage of the kit-built Lotus Seven came to an end. (Note that VAT does allow for variable rating and even zero-rating" of certain goods and services; but the Government still opted not to indulge the kit-builder).
In 1973, Lotus decided to shed fully its "British tax system"-inspired kit car
image and concentrate on limited series motor racing cars. As part of this plan, it sold the rights to the Seven to its only remaining agents Caterham Cars
. After a brief period producing the Series 4, including assembly of the last "kits" supplied by Lotus, Caterham introduced their version of the Series 3, and have been manufacturing and refining this car ever since as the Caterham Seven.
Because of the Seven's relatively simple design, over 160 companies have offered replicas or Seven-type cars over the years. Such cars are often referred to as "sevenesque" or simply a "seven" or "se7en". Sometimes they are also called clubmans
. Some examples are:
Also see :Category:Lotus Seven replicas
in 1958. It was found to have a top speed of 80.4 mph (129.4 km/h), could accelerate from 0-60 mph (96.6 km/h) in 16.2 seconds and had a fuel consumption of 31 mpgimp. The test car cost £1157 including taxes of £386. They commented that car could be bought in component form and then it would have cost £399 for the parts from Lotus, £100 for the Ford engine and gearbox and £27 for the BMC rear axle.
through a speed-trap at the 1962 Natal Grand Prix
. In addition, clamshell style wings tend to create drag
and generate lift at higher speeds. Cycle guards help alleviate this tendency, and low height Brookland aeroscreens that replace the windscreen help improve top end speed.
Physics favours small cars in braking and Sevens have excellent stopping distances, but one of the effects of light weight and powerful (non ABS
) brakes is the tendency to lock up, especially at the front under strong braking. The cooling surface-to-weight ratio improves with reduced scale, while the light weight makes vacuum assistance unnecessary.
The front/rear weight distribution is nearly equal and the lack of a boot and small petrol tank assure that it remains fairly constant. It is, however, more front-heavy than more modern high performance cars.
is traditional, but for the purpose of reducing weight, the upper suspension integrated an anti-roll (anti-sway) bar into a horizontal suspension arm. This approach formed a pseudo-wishbone which was semi-independent in nature. This approach worked well with early crossply tyres, but with later radials, the configuration seriously affected its adjustability.
For the rear suspension, Lotus originally used a live axle
(or solid axle) . This approach was very cost effective since most production saloon cars up to the 1980s used these components. A mixture of Ford, Austin (Rover) components were used. The disadvantage of live axles is higher unsprung weight
since the springs (and shock absorber
) have to carry the weight of the axle and differential, affecting handling and ride on rough surfaces.
While the car's frontal area is small, the Lotus Seven has the highest drag coefficient
of any known production car—ranging from 0.65 to 0.75, depending on bodywork. The introduction of the Series IV Seven improved the car's Cd.
Additionally, the clamshell front wings
develop lift. This is accentuated by the slight natural lift caused by rotating wheels. Consequently, Sevens have exhibited understeer at high speeds.
coupe, it had a multi-tube space frame with high sides to allow a stiffer frame (longer lever arm). However, the Series II and other road versions had simpler frames than the more race oriented Series I.
It is a stressed skin
https://www.cnet.navy.mil/nascweb/sas/stress.htm construction, in which the flat aluminium body panels, and especially the floor, triangulate the largely rectangular steel tubular frame structure. This gives a rigid frame with few tubes and very little body weight that does not contribute to the frame stiffness. The flat panels avoid difficulties in shaping aluminum sheet into smooth compound curves. On the down side, it does not allow "sexy" curves or streamlining.
(L head or side valve) with 49 hp (37 kW), a BMC series A
was used, then push rod overhead valve
(OHV) Fords of 1,340 cc and 1,500 cc with the intake and exhaust on the same side of the head. These were often Cosworth
modified; the Cosworth 1,340 cc "Super Seven" delivered 85 bhp and the 1,500 cc "Super Seven 1500" 105 bhp . These were later replaced by the Ford Kent engine
, better known as the Ford crossflow, in 1,600 cc and 1,700 cc models designated SuperSprints; in their 1,700 cc guise, a crossflow delivers up to 135 bhp . The acceleration finally caught up to the handling when the Cosworth/Ford Twin Cam 1,600, as in the Lotus Elan
, was used. There was also a model, sold in the US with a Coventry Climax
engine and independent rear suspension.
The geometry and high (relative to total) unsprung weight gave it some bump steer, which owners sometimes treated by moving the supports forward and lengthening the trailing arms.
A model that was sold in the US had independent rear suspension and a Coventry Climax
engine.
Companion estate car (station wagon
) rear axle and differential. This was later solved on the Series III with a Ford Cortina
rear end.
The tubular spaceframe chassis suffered from rust, especially from the inside which would lead to its sudden and unexpected collapse.
Lotus Seven 1957-1980
Edited by R.M. Clarke, Brooklands Books, 1980, ISBN 0 907 073 131, Test reports and articles from magazines around the world.
Lotus Seven Collection No. 1, 1957-1982
Edited by R.M. Clarke, Brooklands Books, 1982, ISBN 0 907 073 506, Test reports and articles from magazines around the world.
Lotus & Caterham Sevens Gold Portfolio, 1957-1989
Edited by R.M. Clarke, Brooklands Books, 1989, ISBN 1 85520 0007, Test reports and articles from magazines around the world.
Lotus Seven Gold Portfolio 1957-1973
R.M. Clarke, Brooklands Books, 1996 ISBN 9781855203297, Test reports and articles from magazines around the world.
Lotus Caterham Seven Gold Portfolio, 1974-95
edited by R.M. Clarke, Brooklands Books, 1996, ISBN-10: 1855203308, ISBN-13: 978-1855203303, Test reports and articles from magazines around the world
The Legend of the Lotus Seven
Dennis Ortenberger, Osprey, 1981, ISBN 0-85045-411-5 (Reissued in 1999 by Mercian manuals.)
Lotus Seven Super Profile
by Graham Arnold, Foulis Motoring Book, Haynes Publishing Group, 1984, ISBN 0 85429 385 X
The Lotus and Caterham Sevens, A Collector’s Guide
Jeremy Coulter, Motor Racing Publications Ltd., 1986, ISBN 0 947981 06 3
Lotus Seven: Collector's Guide
by Jeremy Coulter, Motorbooks International, 1994, ISBN-10: 0947981713, ISBN-13: 978-0947981716
Lotus Seven: Restoration, Preparation, Maintenance
by Tony Weale, Osprey Automotive, 1991, ISBN 1-85532-153-X
Side Glances, Volumes 1, 2, 3 and 4
by Peter Egan, Brooklands Books and Road & Track, ISBN 1-855-20567-X
Peter Egan's books are collections of his Road & Track column Side Glances many of which feature his Lotus Sevens.
Lotus and Caterham Seven: Racers for the Road
by John Tipler, Crowood Press, 2005, ISBN-10: 1861267541, ISBN-13: 978-1861267542
The Magnificent 7: The enthusiasts' guide to all models of Lotus and Caterham Seven
by Chris Rees, Haynes Publishing, Second edition 2007, ISBN-10: 1844254100 ISBN-13: 978-1844254101
Why build a Seven? Putting a Sportscar on the Road, a personal record.
by Michael Eddenden, 2010, Published by lulu.com, ISBN 978-0-557-54398-4
The building of a Caterham Seven from a Club perspective, it includes much on the owners of Lotus Sevens.
Sports car
A sports car is a small, usually two seat, two door automobile designed for high speed driving and maneuverability....
produced by Lotus Cars
Lotus Cars
Lotus Cars is a British manufacturer of sports and racing cars based at the former site of RAF Hethel, a World War II airfield in Norfolk. The company designs and builds race and production automobiles of light weight and fine handling characteristics...
(initially called Lotus Engineering) between 1957 and 1972.
It was designed by Lotus founder Colin Chapman
Colin Chapman
Anthony Colin Bruce Chapman CBE was an influential British designer, inventor, and builder in the automotive industry, and founder of Lotus Cars....
and has been considered the embodiment of the Lotus philosophy of performance through low weight and simplicity. The original model was highly successful with more than 2,500 cars sold, due to its attraction as a road legal car that could be used for clubman racing
Clubmans
Clubmans are prototype front-engined sports racing cars that originated in Britain in 1965 and remain a very popular class of racing. Initiated by Nick Syrett of the British Racing and Sports Car Club and organised by the Clubmans Register which represent car owners, drivers and constructors...
.
After Lotus ended production of the Seven, Caterham
Caterham Cars
Caterham Cars is a manufacturer of specialist lightweight sports cars based in Caterham, Surrey, England and part of the British motor industry. Their only current model, the Caterham 7 , is a direct evolution of the Series 3 Lotus Seven designed by Colin Chapman and originally launched in 1968. A...
bought the rights to it, and today make both kits and fully assembled cars based on the original design.
The Lotus Seven design has spawned a host of imitations on the kit car
Kit car
A kit car, also known as a "component car", is an automobile that is available as a set of parts that a manufacturer sells and the buyer then either assembles into a car themselves, or retains a third party to do part or all of the work on their behalf...
market, generally called Sevens or sevenesque roadsters. Many of those cars are still produced to this day. Along with manufacturer supplied kits, there are entirely self-built sevenesque cars referred to as Locost
Locost
A Locost is a home-built clone of the Lotus Seven. The car features a space frame chassis usually welded together from mild steel square tubing. Front suspension is usually double wishbone with coil overs. The rear is traditionally live axle, but has many variants including independent rear...
s.
History
The Lotus Seven was launched in 1957, after the Lotus ElevenLotus Eleven
The Lotus Eleven was a racing car built in various versions by Lotus from 1956 until 1958. The later versions built in 1958 are sometimes referred to as Lotus 13, although this was not an official designation...
was in limited production. The Seven name was left over from a model that was abandoned by Lotus, which would have been a Riley-engined single-seater that Lotus intended to enter into the Formula Two
Formula Two
Formula Two, abbreviated to F2, is a type of open wheel formula racing. It was replaced by Formula 3000 in 1985, but the FIA announced in 2008 that Formula Two would return for 2009 in the form of the FIA Formula Two Championship...
in 1952 or 1953. However, the car was completed around Chapman's chassis as a sports car by its backers and christened the Clairmonte Special.
Based on Chapman's first series-produced Lotus Mark VI, the Seven was powered by a 40 bhp Ford
Ford Motor Company
Ford Motor Company is an American multinational automaker based in Dearborn, Michigan, a suburb of Detroit. The automaker was founded by Henry Ford and incorporated on June 16, 1903. In addition to the Ford and Lincoln brands, Ford also owns a small stake in Mazda in Japan and Aston Martin in the UK...
Side-valve 1,172 cc inline-four engine. It was mainly for lower budget club racing on short tracks (750 motor club).
The Lotus Seven Series 2 (S2) followed in 1960, and the Series 3 (S3) in 1968. In 1970, Lotus radically changed the shape of the car to create the slightly more conventional sized Series 4 (S4), with a squarer fibreglass shell replacing most of the aluminium bodywork. It also offered some "luxuries" as standard, such as an internal heater matrix. The S4 model was not widely welcomed, and Lotus sold few cars. What is believed to be the oldest of these Series 4's survives to this day, and can be seen most weekends around Sussex and Kent. A familiar face at Lotus events up and down the country, this was the second Series 4 ever built, and has proved critics of the S4 wrong; it's looks ageing better than many predicted, and its performance and reliability unsurpassed by any of the original Sevens.
The British tax system of the time (Purchase Tax) meant the car could be supplied as a kit (known as "completely knocked down" or CKD) without attracting the tax surcharge that would apply if sold in assembled form. Tax rules specified assembly instructions could not be included, but in a typical Chapman-inspired piece of lateral thinking, there was no rule covering the inclusion of disassembly instructions. Hence all the enthusiast had to do was to follow these in reverse.
Having joined the EEC on 1 January 1973, the UK had to abolish Purchase Tax and adopt VAT instead. VAT does not allow for concessions such as "CKD", so the tax advantage of the kit-built Lotus Seven came to an end. (Note that VAT does allow for variable rating and even zero-rating" of certain goods and services; but the Government still opted not to indulge the kit-builder).
In 1973, Lotus decided to shed fully its "British tax system"-inspired kit car
Kit car
A kit car, also known as a "component car", is an automobile that is available as a set of parts that a manufacturer sells and the buyer then either assembles into a car themselves, or retains a third party to do part or all of the work on their behalf...
image and concentrate on limited series motor racing cars. As part of this plan, it sold the rights to the Seven to its only remaining agents Caterham Cars
Caterham Cars
Caterham Cars is a manufacturer of specialist lightweight sports cars based in Caterham, Surrey, England and part of the British motor industry. Their only current model, the Caterham 7 , is a direct evolution of the Series 3 Lotus Seven designed by Colin Chapman and originally launched in 1968. A...
. After a brief period producing the Series 4, including assembly of the last "kits" supplied by Lotus, Caterham introduced their version of the Series 3, and have been manufacturing and refining this car ever since as the Caterham Seven.
Replicas
Clubmans
Clubmans are prototype front-engined sports racing cars that originated in Britain in 1965 and remain a very popular class of racing. Initiated by Nick Syrett of the British Racing and Sports Car Club and organised by the Clubmans Register which represent car owners, drivers and constructors...
. Some examples are:
- AlmacAlmac' is a contract research organization based in the United Kingdom. Headquartered in Craigavon, Northern Ireland, the company employs about 3,300 in the United Kingdom and United States. The company provides integrated drug development services, research, manufacturing, to over 600 clients. Core...
a kit car manufacturer in New Zealand - Aries MotorsportAries MotorsportAries MotorSport Ltd is a British kit car manufacturer based in Ilkeston, Derbyshire. The company was created in April 2007 and is the distributor of the Stuart Taylor Locost and LocoBlade kits...
Locoblade and Locost in the UK - Birkin S3, Lotus Seven replica
- BWE LocustLocust (car)Locust is a kit car inspired by the Lotus 7.The Locust Seven differs from most other Lotus / kit cars in that it does not use a space frame chassis, but a ladder frame and a body constructed from three 8ft by 4ft sheets of 3/4" thick exterior grade or marine plywood alternatively MDF sheets...
, HornetHornet (car)The Hornet is a Lotus Seven copy built by T&J Sportscars. The Hornet was created by T&J Sportscars and was designed to take the majority of components from the Ford Cortina mk 3, 4 or 5. This means there is a choice of 1300/ 1600 OHV Kent or OHC 1600/2000 OHC Pinto Ford engines...
, GrasshopperGrasshopper (car)The Grasshopper is a children's Lotus Seven type car. It is a smaller version of the Locust Seven kit car. It is built using the same methods as the full size version with the body tub built from plywood or MDF .... - CaterhamCaterham CarsCaterham Cars is a manufacturer of specialist lightweight sports cars based in Caterham, Surrey, England and part of the British motor industry. Their only current model, the Caterham 7 , is a direct evolution of the Series 3 Lotus Seven designed by Colin Chapman and originally launched in 1968. A...
owns the rights to reproduce the Lotus Super Seven - Cobra Cars produces the Garbí in Spain with the Yamaha R-1 180 hp engine.
- Dala7Dala7Dala7 is a taller and wider Lotus 7 inspired design using Volvo parts. The idea behind the design was to make a sevenesque car suitable for Swedish conditions, so it was made taller and wider to make it possible for taller persons to sit comfortably and to make it possible to use Volvo parts that...
(a taller and wider design using VolvoVolvo CarsVolvo Car Corporation, or Volvo Personvagnar AB, is a Swedish automobile manufacturer founded in 1927, in Gothenburg, Sweden. It is owned by Zhejiang Geely Holding Group. Volvo was originally formed as a subsidiary company to the ball bearing maker SKF. When Volvo AB was introduced on the Swedish...
parts) - DAX RushDAX RushThe Dax Rush is a lightweight two-seater sports car. It is offered as a kit, and is a popular choice among Kit Car builders. It has a multi-tube triangulated steel space frame chassis, front engine and rear wheel or four wheel drive. The body is constructed in Glass-Reinforced Polymer with...
by Dax CarsDax CarsDax Cars is a British sports car manufacturer founded in 1968 and based in Harlow, Essex, England.The company, whose official name is D.J. Sportscars International Ltd, started as a fibreglass moulding company before becoming the first British company to make a kit based replica of the AC 427 Cobra... - Deman Motorsport
- DonkervoortDonkervoortDonkervoort Automobielen BV is a manufacturer of authentic hand-built and ultra light weight sports cars based in Lelystad in The Netherlands. This car brand was founded in 1978 by Joop Donkervoort....
from NetherlandsNetherlandsThe Netherlands is a constituent country of the Kingdom of the Netherlands, located mainly in North-West Europe and with several islands in the Caribbean. Mainland Netherlands borders the North Sea to the north and west, Belgium to the south, and Germany to the east, and shares maritime borders...
with AudiAudiAudi AG is a German automobile manufacturer, from supermini to crossover SUVs in various body styles and price ranges that are marketed under the Audi brand , positioned as the premium brand within the Volkswagen Group....
-Turbo-Engines - Elfin Sports Cars, Australian manufacturer of the Elfin Type 3 ClubmanElfin Type 3 ClubmanThe Elfin Type 3 is an Australian clubman-style, open body kit car by Elfin. The rear end components were sourced from the Mk 2 Ford Escort....
and Elfin T5 Clubman. - ESTfieldESTfieldESTfield is a Lotus Seven-style car manufactured by RaceTech in Estonia either as a kit car or in key ready form. The design is basically a Locost that has been adapted to take Lada parts instead of the Ford Escort of the original Locost...
from RaceTechRaceTechRaceTech is a company in Estonia that makes karts, the Lotus 7 clone ESTfield and GTest, a two seated, mid-engined sports car kit modelled on the Ford GT40....
(using LadaLadaLada is a trademark of AvtoVAZ, a Russian car manufacturer in Tolyatti, Samara Oblast. All AvtoVAZ vehicles are currently sold under the Lada brand, though this was not always so; Lada was originally AvtoVAZ's export brand for models it sold under the Zhiguli name in the domestic Soviet market...
parts) - EstherEsther (car)Esther is a Lotus 7 type car made in Ugglerum, Sweden. The company was founded by Lars Svensson and Magnus Haferbier in 1987. They started off with a shingle wood board jig which had been used for earlier Lotus 7 copies in the Kalmar area. However new ideas came and the first chassis was sold...
- Fraser ClubmanFraser ClubmanFraser Clubman is a component based car similar to a Lotus Seven Series 3, built in Auckland, New Zealand by Fraser Cars Ltd. Scott and Ida Tristram are the current Managing Directors of Fraser Cars having taken over the company from Neil Fraser in 2006....
from Fraser Cars Ltd - HauserHauserHauser is a German-language surname and may refer to:* Arnold George Hauser , American baseball player* Arnold Hauser , Hungarian art historian* Dwight Hauser screenwriter, actor and producer, father of actor Wings Hauser...
from SwitzerlandSwitzerlandSwitzerland name of one of the Swiss cantons. ; ; ; or ), in its full name the Swiss Confederation , is a federal republic consisting of 26 cantons, with Bern as the seat of the federal authorities. The country is situated in Western Europe,Or Central Europe depending on the definition....
with BMWBMWBayerische Motoren Werke AG is a German automobile, motorcycle and engine manufacturing company founded in 1916. It also owns and produces the Mini marque, and is the parent company of Rolls-Royce Motor Cars. BMW produces motorcycles under BMW Motorrad and Husqvarna brands...
engines - Hispano AllemanHispano Alleman Mallorca
- Höckmayr KFZ-Technik (HKT) from Germany also with Audi-Turbo-Engines
- Irmscher 7 from Germany with OpelOpelAdam Opel AG, generally shortened to Opel, is a German automobile company founded by Adam Opel in 1862. Opel has been building automobiles since 1899, and became an Aktiengesellschaft in 1929...
engines - Kaipan type 47 and 57. Replica from Czech Republic
- Leitch Super SprintLeitch Super SprintThe Leitch Super Sprint is a Lotus Seven replica made by Leitch Motorsport and Restoration, Ltd, in Invercargill, New Zealand.Barry Leitch started building Super Sprints in 1986 and regularly raced them competitively in local classic and sports car racing...
, Leitch Industries, Invercargill, New Zealand - Lucalia Clubman, Lucalia Partnerships, TasmaniaTasmaniaTasmania is an Australian island and state. It is south of the continent, separated by Bass Strait. The state includes the island of Tasmania—the 26th largest island in the world—and the surrounding islands. The state has a population of 507,626 , of whom almost half reside in the greater Hobart...
, AustraliaAustraliaAustralia , officially the Commonwealth of Australia, is a country in the Southern Hemisphere comprising the mainland of the Australian continent, the island of Tasmania, and numerous smaller islands in the Indian and Pacific Oceans. It is the world's sixth-largest country by total area...
; mostly Japanese mechanicals (inline 4) - Luego Sports Cars Velocity and V8 Viento in UK
- MAC #1
- Marc Nordon RacingMarc Nordon RacingMarc Nordon Racing is a kit car manufacturer specialising in bike engined cars or BECs and in particular, Lotus Seven Replicas. They are based in Harrogate, England....
Vortx RT, RT+ and RT Super - McGregor Motorsport Ltd (New Zealand) Lotus Seven replica kits and manufacturers
- MitsuokaMitsuokais a small Japanese automobile company. They are noted for building cars with unconventional styling, some of which imitate British vehicles of the 1950s and 1960s. It is primarily a coachbuilder, taking production cars like the Nissan March and replacing the bodywork with its own custom designs...
Zero 1 from ToyamaToyama Prefectureis a prefecture of Japan located in the Hokuriku region on Honshū island. The capital is the city of Toyama.Toyama is the leading industrial prefecture on the Japan Sea coast, and has the industrial advantage of cheap electricity due to abundant water resources....
, JapanJapanJapan is an island nation in East Asia. Located in the Pacific Ocean, it lies to the east of the Sea of Japan, China, North Korea, South Korea and Russia, stretching from the Sea of Okhotsk in the north to the East China Sea and Taiwan in the south... - MK IndyMK IndyThe MK Indy is a Lotus 7 replica based on the Locost principle, built by MK Sportscars in Maltby, Rotherham. The Indy has an independent rear suspension using the differential and drive shafts from a Ford Sierra. It uses many other components from the Sierra, including front hubs and steering rack...
from MK Engineering (using Ford SierraFord SierraThe Ford Sierra is a large family car that was built by Ford Europe from 1982 until 1993. It was designed by Uwe Bahnsen, Robert Lutz and Patrick le Quément. The code used during development was "Project Toni"....
parts) - Pegasus Automobile from Germany.
- PRB Clubman - manufactured Peter R Bladewell in Strathfield, Sydney Australia.
- Raptor by Tornado Sports Cars
- Several models from Robin Hood Engineering Ltd
- Rotus, originally built with components from Japan in Hagerstown, Maryland. Since founder Chris Custer owned a Toyota dealership, the first cars used a Japanese spec 2litre twin cam Toyota engines and five speed gearbox. Many other engines were used over the years including Mazda rotary up to Rover/Buick V8s.
- Stalker V6 ClubmanStalker V6 ClubmanThe Stalker V6 Clubman made by Brunton Automotive is a kitcar replica of a Lotus Seven .The drivetrain is based on components from the Chevrolet S-10 two-wheel drive pickup truck as sold in the United States and Canada from the mid 1980s through the early 1990s. Older Stalker used the 2.8 or 3.4 l...
by Brunton Automotive USA Bradenton, Florida USA - Superformance S1 RoadsterSuperformanceSuperformance LLC is a small American automobile company that builds, designs, and imports sports cars and replicars. The company was founded as "Superformance International Inc." by Hi-Tech Automotive Ltd. in 1996. Today, Superformance has 15 authorized dealers in the United States and 6...
- Super Martin from France
- Tiger Z100, Tiger R6, Tiger B6 & Tiger Cat E1 from Tiger Racing Ltd
- TSV a great Lotus 7 replica From Greece
- Vindicator Sprint and the four seat Vindicator Family by Vindicator Cars
- Westfield Sportscars produces several models
Also see :Category:Lotus Seven replicas
Road test
A car with a tuned Ford 1172 cc engine and close ratio gearbox was tested by the British magazine The MotorThe Motor (magazine)
The Motor was a British weekly car magazine founded on 28 January 1903....
in 1958. It was found to have a top speed of 80.4 mph (129.4 km/h), could accelerate from 0-60 mph (96.6 km/h) in 16.2 seconds and had a fuel consumption of 31 mpgimp. The test car cost £1157 including taxes of £386. They commented that car could be bought in component form and then it would have cost £399 for the parts from Lotus, £100 for the Ford engine and gearbox and £27 for the BMC rear axle.
Top speed
A Seven's top speed greatly depends upon the body configuration, engine power and gearing. Early models with low-powered engines had difficulty exceeding 90 mi/h, although a race-prepared Seven was clocked at 127 mi/h by Brausch NiemannBrausch Niemann
Ambraüsus "Brausch" Niemann is a former racing driver from South Africa. He participated in 2 Formula One World Championship Grands Prix in 1963 and 1965, both in his home country, driving a privately-entered Lotus...
through a speed-trap at the 1962 Natal Grand Prix
1962 Natal Grand Prix
The 2nd Natal Grand Prix was a motor race, run to South African Formula One-style rules, held on 22 December 1962 at Westmead Circuit, South Africa. The field was split into two heats, with a subsequent final...
. In addition, clamshell style wings tend to create drag
Drag coefficient
In fluid dynamics, the drag coefficient is a dimensionless quantity that is used to quantify the drag or resistance of an object in a fluid environment such as air or water. It is used in the drag equation, where a lower drag coefficient indicates the object will have less aerodynamic or...
and generate lift at higher speeds. Cycle guards help alleviate this tendency, and low height Brookland aeroscreens that replace the windscreen help improve top end speed.
Low speed acceleration
Nearly all Sevens, due to their extremely light weight (around 10cwt / 500 kg) have excellent acceleration, especially up to 70 mi/h, depending on power. For their time, the original late 1950s Sevens could beat most contemporary saloon cars—and by the early 1960s, with improved Ford-Cosworth engines could take on most high performance sports cars with 0–60 mph time in the low 7 seconds.Braking
The choice of brakes vary considerably between models and over the evolution of the car. The less powerful early models had drum brakes all round, while more powerful and later models had drums at the rear only (especially on live axle cars from the early 1960s) or discs all round. With the popularity of semi-independent (DeDion) or fully independent Rear suspension most manufacturers have opted for discs all round, as is current common practice in the automotive industry.Physics favours small cars in braking and Sevens have excellent stopping distances, but one of the effects of light weight and powerful (non ABS
Anti-lock braking system
An anti-lock braking system is a safety system that allows the wheels on a motor vehicle to continue interacting tractively with the road surface as directed by driver steering inputs while braking, preventing the wheels from locking up and therefore avoiding skidding.An ABS generally offers...
) brakes is the tendency to lock up, especially at the front under strong braking. The cooling surface-to-weight ratio improves with reduced scale, while the light weight makes vacuum assistance unnecessary.
Handling
The highest part of the car is about three feet from the road and it has a cloth top and side curtains with plastic back and side windows. The supports for the top and the windshield frame are aluminium. The lower chassis tubes are five inches (127 mm) from the road, while the wet sump, bell housing and one chassis tube are lower, meaning the centre of gravity is very low.The front/rear weight distribution is nearly equal and the lack of a boot and small petrol tank assure that it remains fairly constant. It is, however, more front-heavy than more modern high performance cars.
Suspension
In the original Seven, the front lower A-arm (or "wishbone") of the double wishbone suspensionSuspension (vehicle)
Suspension is the term given to the system of springs, shock absorbers and linkages that connects a vehicle to its wheels. Suspension systems serve a dual purpose — contributing to the car's roadholding/handling and braking for good active safety and driving pleasure, and keeping vehicle occupants...
is traditional, but for the purpose of reducing weight, the upper suspension integrated an anti-roll (anti-sway) bar into a horizontal suspension arm. This approach formed a pseudo-wishbone which was semi-independent in nature. This approach worked well with early crossply tyres, but with later radials, the configuration seriously affected its adjustability.
For the rear suspension, Lotus originally used a live axle
Live axle
A live axle, sometimes called a solid axle, is a type of beam axle suspension system that uses the driveshafts that transmit power to the wheels to connect the wheels laterally so that they move together as a unit....
(or solid axle) . This approach was very cost effective since most production saloon cars up to the 1980s used these components. A mixture of Ford, Austin (Rover) components were used. The disadvantage of live axles is higher unsprung weight
Unsprung weight
In a ground vehicle with a suspension, the unsprung weight is the mass of the suspension, wheels or tracks , and other components directly connected to them, rather than supported by the suspension...
since the springs (and shock absorber
Shock absorber
A shock absorber is a mechanical device designed to smooth out or damp shock impulse, and dissipate kinetic energy. It is a type of dashpot.-Nomenclature:...
) have to carry the weight of the axle and differential, affecting handling and ride on rough surfaces.
Aerodynamics
In general, cars with non-optimized aerodynamics tend to be free of adverse aerodynamic effects on handling, but the front wheel arches, of all but the Series I, cause lift at high speeds. Like the good straight line performance, the car's nimble handling is limited in speed range. It can be argued that this is not usually important in a car intended for public roads.While the car's frontal area is small, the Lotus Seven has the highest drag coefficient
Drag coefficient
In fluid dynamics, the drag coefficient is a dimensionless quantity that is used to quantify the drag or resistance of an object in a fluid environment such as air or water. It is used in the drag equation, where a lower drag coefficient indicates the object will have less aerodynamic or...
of any known production car—ranging from 0.65 to 0.75, depending on bodywork. The introduction of the Series IV Seven improved the car's Cd.
Additionally, the clamshell front wings
Fender (vehicle)
Fender is the US English term for the part of an automobile, motorcycle or other vehicle body that frames a wheel well . Its primary purpose is to prevent sand, mud, rocks, liquids, and other road spray from being thrown into the air by the rotating tire. Fenders are typically rigid and can be...
develop lift. This is accentuated by the slight natural lift caused by rotating wheels. Consequently, Sevens have exhibited understeer at high speeds.
Steering
The rack and pinion steering provides a minimum of play and friction. The light weight assures light steering without power assistance, even with very large tyres. The ratio is quick.Rigidity of the frame
Like racing cars of the time and the equally respected and more expensive Mercedes-Benz 300SLMercedes-Benz 300SL
The Mercedes-Benz 300SL was introduced in 1954 as a two-seat, closed sports car with distinctive gull-wing doors. Later it was offered as an open roadster...
coupe, it had a multi-tube space frame with high sides to allow a stiffer frame (longer lever arm). However, the Series II and other road versions had simpler frames than the more race oriented Series I.
It is a stressed skin
Stressed skin
In mechanical engineering, stressed skin is a type of rigid construction, intermediate between monocoque and a rigid frame with a non-loaded covering:...
https://www.cnet.navy.mil/nascweb/sas/stress.htm construction, in which the flat aluminium body panels, and especially the floor, triangulate the largely rectangular steel tubular frame structure. This gives a rigid frame with few tubes and very little body weight that does not contribute to the frame stiffness. The flat panels avoid difficulties in shaping aluminum sheet into smooth compound curves. On the down side, it does not allow "sexy" curves or streamlining.
Engines
After the English Ford flatheadFlathead engine
A flathead engine is an internal combustion engine with valves placed in the engine block beside the piston, instead of in the cylinder head, as in an overhead valve engine...
(L head or side valve) with 49 hp (37 kW), a BMC series A
BMC A-Series engine
Austin Motor Company's small straight-4 automobile engine, the A-Series, is one of the most common in the world. Launched in 1951 with the Austin A30, production lasted until 2000 in the Mini. It used a cast-iron block and cylinder head, and a steel crankshaft with 3 main bearings...
was used, then push rod overhead valve
Overhead valve
An overhead valve engine, also informally called pushrod engine or I-head engine, is a type of piston engine that places the camshaft within the cylinder block , and uses pushrods or rods to actuate rocker arms above the cylinder...
(OHV) Fords of 1,340 cc and 1,500 cc with the intake and exhaust on the same side of the head. These were often Cosworth
Cosworth
Cosworth is a high performance engineering company founded in London in 1958, specialising in engines and electronics for automobile racing , mainstream automotive and defence industries...
modified; the Cosworth 1,340 cc "Super Seven" delivered 85 bhp and the 1,500 cc "Super Seven 1500" 105 bhp . These were later replaced by the Ford Kent engine
Ford Kent engine
The Ford Kent is an internal combustion engine from Ford of Europe. Originally developed in 1959 for the Ford Anglia, it is an in-line four-cylinder engine with a cast-iron cylinder head and block.-Pre-Crossflow:...
, better known as the Ford crossflow, in 1,600 cc and 1,700 cc models designated SuperSprints; in their 1,700 cc guise, a crossflow delivers up to 135 bhp . The acceleration finally caught up to the handling when the Cosworth/Ford Twin Cam 1,600, as in the Lotus Elan
Lotus Elan
Lotus Elan is the name of two convertible cars and one fixed head coupé produced by Lotus Cars. The original Type 26, 26R Racing version , 36R Racing version , 36 Fixed Head Coupe, 45 Drop Head Coupe, and the "Type 50" +2 Coupe, circa 1962 to 1975, are commonly known as the '60s Elans...
, was used. There was also a model, sold in the US with a Coventry Climax
Coventry Climax
Coventry Climax was a British forklift truck, fire pump, and speciality engine manufacturer.-History:The company was started in 1903 as Lee Stroyer, but two years later, following the departure of Stroyer, it was relocated to Paynes Lane, Coventry, and renamed to Coventry-Simplex by H...
engine and independent rear suspension.
Frame and body
The Lotus Seven was designed with racing in mind, and lightness was of primary concern to Chapman. A front mounted engine driving the rear wheels (a similar layout to most cars of the day) and a very lightweight steel spaceframe was covered with unstressed aluminium panel bodywork. The body panels were mainly flat to avoid the expense of more elaborate curved bodywork, and the simple cloth lined plastic doors were hinged from the windscreen. The nose-cone and wheel arches were originally aluminium parts, but these were replaced in the later S2 and S3 models with painted or self-coloured fibreglass.Weight
Early Lotus Sevens weighed around 1,100 lb (10cwt/500 kg). Although the weight crept upward as production progressed, it remained remarkably low for a production car of over a litre displacement.Suspension
The front was by "A" arms and coil springs with an anti-roll bar serving as the front half of the top A arm. The rear had trailing arms, a triangular centre locating member and solid rear axle.The geometry and high (relative to total) unsprung weight gave it some bump steer, which owners sometimes treated by moving the supports forward and lengthening the trailing arms.
A model that was sold in the US had independent rear suspension and a Coventry Climax
Coventry Climax
Coventry Climax was a British forklift truck, fire pump, and speciality engine manufacturer.-History:The company was started in 1903 as Lee Stroyer, but two years later, following the departure of Stroyer, it was relocated to Paynes Lane, Coventry, and renamed to Coventry-Simplex by H...
engine.
Problem areas
The series II had problems with its StandardStandard Motor Company
The Standard Motor Company was founded in Coventry, England in 1903 by Reginald Walter Maudslay . The Standard name was last used in Britain in 1963, and in India in 1987.-1903–1914:...
Companion estate car (station wagon
Station wagon
A station wagon is a body style variant of a sedan/saloon with its roof extended rearward over a shared passenger/cargo volume with access at the back via a third or fifth door , instead of a trunk lid...
) rear axle and differential. This was later solved on the Series III with a Ford Cortina
Ford Cortina
As the 1960s dawned, BMC were revelling in the success of their new Mini – the first successful true minicar to be built in Britain in the postwar era...
rear end.
The tubular spaceframe chassis suffered from rust, especially from the inside which would lead to its sudden and unexpected collapse.
Lotus Seven in the media
- An S2 Lotus Seven (registration KAR 120C) driven by star Patrick McGoohanPatrick McGoohanPatrick Joseph McGoohan was an American-born actor, raised in Ireland and England, with an extensive stage and film career, most notably in the 1960s television series Danger Man , and The Prisoner, which he co-created...
was featured in the 1967–1968 television series The PrisonerThe PrisonerThe Prisoner is a 17-episode British television series first broadcast in the UK from 29 September 1967 to 1 February 1968. Starring and co-created by Patrick McGoohan, it combined spy fiction with elements of science fiction, allegory and psychological drama.The series follows a British former...
. The registration plate is still held by Caterham Cars.
- Marvel ComicsMarvel ComicsMarvel Worldwide, Inc., commonly referred to as Marvel Comics and formerly Marvel Publishing, Inc. and Marvel Comics Group, is an American company that publishes comic books and related media...
superhero WolverineWolverine (comics)Wolverine is a fictional character, a superhero that appears in comic books published by Marvel Comics. Born as James Howlett and commonly known as Logan, Wolverine is a mutant, possessing animal-keen senses, enhanced physical capabilities, three retracting bone claws on each hand and a healing...
drives a Lotus Seven.
- A Lotus Seven appears as one of the steal-able cars in Grand Theft Auto: London 1969, under the name "LocustLocust (car)Locust is a kit car inspired by the Lotus 7.The Locust Seven differs from most other Lotus / kit cars in that it does not use a space frame chassis, but a ladder frame and a body constructed from three 8ft by 4ft sheets of 3/4" thick exterior grade or marine plywood alternatively MDF sheets...
". Ironically enough there is a replica of the Lotus Seven made under the same name and another version made under the trade name of the LocostLocostA Locost is a home-built clone of the Lotus Seven. The car features a space frame chassis usually welded together from mild steel square tubing. Front suspension is usually double wishbone with coil overs. The rear is traditionally live axle, but has many variants including independent rear...
.
- In the games Sonic DriftSonic DriftThe Sonic Drift games were a series of two racing games that featured characters from the Sonic the Hedgehog series. It was released for the Sega Game Gear in 1994 and 1995 respectively, and later re-released many years later in several other compilations.-Sonic Drift:Sonic Drift is a kart racing...
and Sonic Drift 2, Tails uses a car called the "Whirlwind S7", which is a reference to the Lotus S7.
- A Super Seven is driven by the character Sena Wakabayashi in the anime series You're Under Arrest.
- Sōichi Sugano from the anime éX-DriverÉX-Driveris a manga series by Kōsuke Fujishima, which was adapted into an anime series, produced by Bandai Visual and XEBEC. The anime series spanned 6 episodes, as well as a feature movie, entitled éX-Driver: The Movie...
drives a Super Seven. This series contains several Lotus models, but the Seven is most prominent.
- Jim Skylark from the anime Gate KeepersGate Keepersis primarily a role-playing game for the PlayStation. The game was then adapted into a manga series written by and drawn by Keiji Gotoh and an anime series produced by Gonzo, and first aired on April 3, 2000.....
drives a Super Seven with license plate AEGIS 02. In the series he debuted in the car, outrunning Shun Ukiya's Toyota Sports 800Toyota Sports 800The Toyota Sports 800 was Toyota Motor Corporation's first production sports car. The prototype for the Sports 800, called the Toyota Publica Sports, debuted at the 1962 Tokyo Auto Show, featuring a space age sliding canopy and utilizing the power train of the Toyota Publica 700, a Japanese market...
on the freeway.
- On the "Is born" series on the Discovery ChannelDiscovery ChannelDiscovery Channel is an American satellite and cable specialty channel , founded by John Hendricks and distributed by Discovery Communications. It is a publicly traded company run by CEO David Zaslav...
Mark Evans built a Westfield Sportscars SEi from a kit.
- In the BBC TV Series Top Gear, Richard HammondRichard HammondRichard Mark Hammond is an English broadcaster, writer, and journalist most noted for co-hosting car programme Top Gear with Jeremy Clarkson and James May, as well as presenting Brainiac: Science Abuse on Sky 1.-Early life:...
, James MayJames MayJames Daniel May is an English television presenter, journalist and writer. He is best known for his role as co-presenter of the award-winning motoring programme Top Gear alongside Jeremy Clarkson and Richard Hammond....
and Jeremy ClarksonJeremy ClarksonJeremy Charles Robert Clarkson is an English broadcaster, journalist and writer who specialises in motoring. He is best known for his role on the BBC TV show Top Gear along with co-presenters Richard Hammond and James May...
were at Knockhill Racing CircuitKnockhill Racing CircuitKnockhill Racing Circuit in Fife is Scotland's national Motorsport centre. The circuit is located in the Fife countryside about north of Dunfermline. The track, initially opened in 1974, is long and 10 metres wide and was created by joining service roads to a nearby disused mineral railway,...
in Fife, Scotland "racing" against The Stig. The race was not a normal race as the winner was deemed to be the team who arrived on the race track and started their engine first. The Stig was based at the Caterham Factory in Surrey racing a factory built and the three presenters were actually at the racetrack building the car from scratch. The race was in order to determine whether it was quicker to build a car from scratch or to actually purchase and drive one from the factory. In the race the team won (mainly because of the low capacity of the Lotus 7's petrol tank - and because the Stig was unable to answer any questions about the car when stopped by police just as he was about to win), however the build quality of the presenter's car could not be determined.
Lotus Seven literature
The Lotus Seven has spawned many books, test reports and articles, many of which are still in print.Lotus Seven 1957-1980
Edited by R.M. Clarke, Brooklands Books, 1980, ISBN 0 907 073 131, Test reports and articles from magazines around the world.
Lotus Seven Collection No. 1, 1957-1982
Edited by R.M. Clarke, Brooklands Books, 1982, ISBN 0 907 073 506, Test reports and articles from magazines around the world.
Lotus & Caterham Sevens Gold Portfolio, 1957-1989
Edited by R.M. Clarke, Brooklands Books, 1989, ISBN 1 85520 0007, Test reports and articles from magazines around the world.
Lotus Seven Gold Portfolio 1957-1973
R.M. Clarke, Brooklands Books, 1996 ISBN 9781855203297, Test reports and articles from magazines around the world.
Lotus Caterham Seven Gold Portfolio, 1974-95
edited by R.M. Clarke, Brooklands Books, 1996, ISBN-10: 1855203308, ISBN-13: 978-1855203303, Test reports and articles from magazines around the world
The Legend of the Lotus Seven
Dennis Ortenberger, Osprey, 1981, ISBN 0-85045-411-5 (Reissued in 1999 by Mercian manuals.)
Lotus Seven Super Profile
by Graham Arnold, Foulis Motoring Book, Haynes Publishing Group, 1984, ISBN 0 85429 385 X
The Lotus and Caterham Sevens, A Collector’s Guide
Jeremy Coulter, Motor Racing Publications Ltd., 1986, ISBN 0 947981 06 3
Lotus Seven: Collector's Guide
by Jeremy Coulter, Motorbooks International, 1994, ISBN-10: 0947981713, ISBN-13: 978-0947981716
Lotus Seven: Restoration, Preparation, Maintenance
by Tony Weale, Osprey Automotive, 1991, ISBN 1-85532-153-X
Side Glances, Volumes 1, 2, 3 and 4
by Peter Egan, Brooklands Books and Road & Track, ISBN 1-855-20567-X
Peter Egan's books are collections of his Road & Track column Side Glances many of which feature his Lotus Sevens.
Lotus and Caterham Seven: Racers for the Road
by John Tipler, Crowood Press, 2005, ISBN-10: 1861267541, ISBN-13: 978-1861267542
The Magnificent 7: The enthusiasts' guide to all models of Lotus and Caterham Seven
by Chris Rees, Haynes Publishing, Second edition 2007, ISBN-10: 1844254100 ISBN-13: 978-1844254101
Why build a Seven? Putting a Sportscar on the Road, a personal record.
by Michael Eddenden, 2010, Published by lulu.com, ISBN 978-0-557-54398-4
The building of a Caterham Seven from a Club perspective, it includes much on the owners of Lotus Sevens.
External links
- LocostBuilders.gr Portal for locost builders from Greece.
- TSV.gr A Lotus 7 replica From Greece
- Factor Seven - Web resource and news portal for Sevens and Seven-inspired cars * Club francophone de Seven dédié à la célèbre Lotus Seven, aux Caterham, Westfield, Martin, et autres véhicules inspirés de ce concept
- Se7en-up - Lotus Seven history, information and specifications
- Caterham Graduates Racing ClubCaterham Graduates Racing ClubCaterham Graduates Racing Club is a British motor-racing club for privateer racing drivers in Caterham Seven type cars.-History:The Caterham Graduates Championship was started in 1998 by competitors from the 1997 Caterham Scholarship...
- Historic Lotus Register for the history & ownership of individual Lotus Seven Series 1, 2 & 3 cars
- The Lotus Seven Club
- The Lotus Seven Club's Internet forums
- Comprehensive history of the Lotus Seven sportscar, technical specifications, reviews and projects
- Lotus Seven Club Sweden
- Lotus Klub Danmark (Lotus Club Denmark)
- Caterham official website (UK)
- Caterham USA
- The California Caterham Club
- Seven Builder: How Lotus & Caterham Sevens are put together
- USA7s Club Site & Forum
- LocostUSA Active forum for active replica builders.
- nise7ens Club for owners of Lotus Seven-inspired sportscars in Northern Ireland
- SimpleSevens.org in the interest of genuine Lotus Sevens and their owners