Lotus Seven
Manufacturer:	Lotus Cars
Production:	1957–1972
Platforms:	Series 1 Series 2 Series 3 Series 4
Class:	Sports car
Body styles:
Engine types:
Predecessor:	Lotus 6
Successor:	Caterham 7, Elise

See also: Caterham Cars

The Lotus Seven was a small, simple, lightweight two-seater open-top sports car produced by Lotus Cars (initially called Lotus Engineering)^[1] 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 2500 cars sold^[2], due to its attraction as a road legal car that could be used for clubman racing^[3]. After Lotus ended production of the Seven, Caterham bought the rights to it, and today make both kits and fully assembled cars. Lotus Logo with initials of its founder, Anthony Colin Bruce Chapman Lotus Cars is a British manufacturer of sports and racing cars based at Hethel, Norfolk, England. ... Lotus Logo, claiming fair use This work is copyrighted. ... 1957 (MCMLVII) was a common year starting on Tuesday of the Gregorian calendar. ... 1972 (MCMLXXII) was a leap year starting on Saturday. ... To meet Wikipedias quality standards, this article or section may require cleanup. ... To meet Wikipedias quality standards, this article or section may require cleanup. ... The Lotus Seven is a small, simple, lightweight two-seater open-top sports car, which have been called a motorcycle on four wheels. It is characterised by very good acceleration but a low top speed, handling is lively and the ride is uncompromising. The drag coefficient is around 0. ... The Lotus Elise is a roadster conceived in early 1994 and released in September 1996 by the English manufacturer Lotus Cars. ... Caterham Cars is a manufacturer of specialist lightweight sports cars based in Caterham, Surrey, England and part of the British motor industry. ... To meet Wikipedias quality standards, this article or section may require cleanup. ... Lotus Logo with initials of its founder, Anthony Colin Bruce Chapman Lotus Cars is a British manufacturer of sports and racing cars based at Hethel, Norfolk, England. ... 1957 (MCMLVII) was a common year starting on Tuesday of the Gregorian calendar. ... 1972 (MCMLXXII) was a leap year starting on Saturday. ... Wikiquote has a collection of quotations related to: Colin Chapman Anthony Colin Bruce Chapman (born 9 May 1928 in London - died 16 December 1982) was an influential designer, inventor, and builder in the automotive industry. ... Caterham Cars is a manufacturer of specialist lightweight sports cars based in Caterham, Surrey, England and part of the British motor industry. ...

History

The Lotus Seven was launched in 1957, after the Lotus Eleven was in limited production. (The name was left over, due to a model that was originally to have had that name having been abandoned by Lotus - this car would have seen Lotus entering Formula Two with a Riley-engined single-seater in 1952 or 53, but the car was completed around Chapman's chassis as a sports car by its backers and called the Clairmonte Special). Based on the first series produced Lotus, the Lotus 6, it was powered by a 40 bhp Ford Side-valve 1172 cc 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. These had even simpler structure and a close look at such details as bushings of rubber, rather than brass or Delrin, as well as removable weather protection and optional heaters and engine fans, shows that they are mainly for use on roads. In 1970, Lotus radically changed the shape of the car to create the slightly more conventional sized Series 4 (S4), with more fibreglass replacing some of the aluminium. Having closer serious competition from all the moderately spartan British sports cars, this model was not accepted widely enough that either Lotus or Caterham continued it for long. The Lotus Eleven on the cover of Road and Track Magazine The Lotus Eleven was a racing car built in various versions by Lotus from 1956 until 1958. ... Formula Two was a type of formula racing. ... To meet Wikipedias quality standards, this article or section may require cleanup. ... BHP may refer to: Broken Hill Proprietary Company BHP Billiton BHP Steel Brake horsepower This page concerning a three-letter acronym or abbreviation is a disambiguation page—a list of articles associated with the same title. ... Ford Motor Company is an American multinational corporation and the worlds third largest automaker based on vehicle sales in 2005. ... The cam-in-block valvetrain layouts are ones in which the camshaft is placed within the cylinder block, usually beside and slightly above the crankshaft in a straight engine or directly above the crankshaft in the V of a V engine. ... A colorized automobile engine The internal combustion engine is a heat engine in which the burning of a fuel occurs in a confined space called a combustion chamber. ... It has been suggested that this article or section be merged into polyoxymethylene. ...

An S2 Lotus 7 driven by star Patrick McGoohan was featured in the 1967–1968 television series The Prisoner. This article or section does not cite its references or sources. ... A television program is the content of television broadcasting. ... The Prisoner was a 1967 UK science fiction television series, starring Patrick McGoohan. ...

In 1973, Lotus decided to shed fully its British tax system-inspired partial kit car image and concentrate on its more up-market models. As part of this plan, it sold the rights to the Seven to Caterham Cars. Caterham had been a Seven dealer since the very early days, and at this time they were the sole suppliers. After a brief period producing the Series 4, including assembly of the last "kits" supplied by Lotus, they introduced their version of the Series 3 car, and have been making, and refining, this car ever since as the Caterham Seven. A kit-car is an automobile that is available in kit form, i. ... Caterham Cars is a manufacturer of specialist lightweight sports cars based in Caterham, Surrey, England and part of the British motor industry. ...

Replicas

Since the design of the Lotus Seven is so simple, over 90 companies have offered replicas or Seven-type cars over the years such as:

• Luego Sports Cars Velocity and V8 Viento in UK
• Almac a kit car manufacturer in New Zealand
• Caterham owns the rights to reproduce the Lotus Super Seven
• Dax Cars ltd
• Westfield Sportscars Ltd produces several models
• Stalker V6 Clubman by Brunton Automotive
• Raptor by Tornado Sports Cars
• Donkervoort from Netherlands with Audi-Turbo-Engines
• HKT from Germany also with Audi-Turbo-Engines
• Hauser from Switzerland with BMW engines
• Tiger Z100 from Z Cars Ltd
• MK Indy from MK Engineering (using Ford Sierra parts)
• Mitsuoka Zero 1 from Toyama, Japan
• ESTfield from RaceTech (using Lada parts)
• Esther [1]
• Several models from Robin Hood Engineering Ltd
• Dala7 (a taller and wider design using Volvo parts) [2]
• Rotus, originally built with components from Japan and a Mazda rotary engine
• Gregory
• Superformance S1 Roadster
• Fraser Clubman from Fraser Cars Ltd
• Vindicator Sprint and the four seat Vindicator Family by Vindicator Cars [3]
• Irmscher 7[4]
• Elfin [5], Australian manufacturer of the MS8 (V8 powered) and Type 3 Clubman
• Super Martin from France
• Pegasus Automobile from Germany.

Caterham Cars is a manufacturer of specialist lightweight sports cars based in Caterham, Surrey, England and part of the British motor industry. ... Westfield Cars are manufacturers of both factory built and kit versions of several two-seater, open top sportscars. ... Stalker V6 Clubman The Stalker V6 Clubman is a facsimili/replica of a Lotus Seven. ... Donkervoort Automobielen is a producer of sports cars based in Lelystad in The Netherlands. ... Audi AG is a German automobile manufacturer with headquarters in Ingolstadt, Bavaria, and is an almost wholly owned (99. ... HKT is a Lotus 7 clone from Germany using Audi turbo engines. ... There are persons that have the last name Hauser: Bodo H. Hauser (1946-2004), German Journalist Eduard Hauser (b. ... This article or section does not cite its references or sources. ... The MK Indy is a Lotus 7 replica based on the Locost principle, built by MK Engineering in Langold, Nottinghamshire. ... A Swedish MK Indy. ... The Ford Sierra was a large family car built by Ford Motor Company in Europe between 1982 and 1993, originally designed by Patrick le Quément. ... 2005 Mitsuoka Orochi Nude-Top Roadstar. ... Toyama (富山市; -shi) is the capital city of Toyama Prefecture, Japan. ... ESTfield is a Lotus Seven-style car manufactured by RaceTech in Estonia either as a kit car or in key ready form. ... Lada logo Lada is the trademark of AutoVAZ, a Russian car manufacturer. ... Esther is a Lotus 7 type car made in Ugglerum, Sweden. ... Dala7 is a taller and wider Lotus 7 inspired design using Volvo parts. ... AB Volvo (or Aktiebolaget Volvo) is a world-leading Swedish manufacturer of commercial vehicles, trucks, buses and construction equipment, drive systems for marine and industrial applications, aerospace components and financial services. ... 12A redirects here. ... A few Gregory cars were produced of different shapes and varietys one was a Lotus 6/7 replica based on a Ford Popular with a Ford Sidevalve engine. ... Fraser Clubman is a high quility component based car similar to a Lotus Seven Series 3, built in Auckland, New Zealand by Fraser Cars Ltd. ... Fraser Cars Ltd is a privately, completely NZ owned company that operates out of Beachhaven, North Shore, Auckland and manufactures Component based cars in kit and complete form since 1988 Fraser Clubman. ...

Analysis of the Seven's performance

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 mph, although a race-prepared Seven was clocked at 127mph by Brausch Niemann through a speed-trap at the 1962 Natal Grand Prix^[4]. 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. Brausch Niemann was a Formula One driver from South Africa. ... In design, clamshell is a form resembling the shell of a clam, with the ability to open up in the same way. ... The drag coefficient (Cd or Cx) is a number that describes a characteristic amount of aerodynamic drag caused by fluid flow, used in the drag equation. ... Automobile windshield. ...

Low speed acceleration

Nearly all Sevens, due to their extremely light weight (around 500 kg) have excellent acceleration, especially up to 70 mph, 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. More recent acceleration times (for top level models) are world beating for production cars with 0–60 mph below 3.5 seconds. The high power-to-weight ratio is excellent with almost any engine.

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) 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. An anti-lock braking system (ABS) is a system on motor vehicles which prevents the wheels from locking while braking. ...

Handling

The highest part of the car is about three feet from the road (similar to a Lamborghini Countach) 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 aluminum. The lower chassis tubes are five inches from the road, while the wet sump, bell housing and one chassis tube are lower. Lamborghini Countach from the top. ...

The front/rear centre of gravity 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 suspension is traditional, but for the purpose of reducing cost, 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.^{[citation needed]} This article or section does not cite its references or sources. ... A double wishbone suspension is an automobile independent suspension design using two parallel wishbone-shaped arms to locate the wheel. ... The front suspension components of a Ford Model T. Suspension is the term given to the system of springs, shock absorbers and linkages that connects a vehicle to its wheels. ...

A number of changes to the front suspension were tried in racing circles in the 1970-80s mostly involving using a full upper wishbone and a separate anti-rollbar and this approach was finally adopted by most manufacturers by the early 1990s. This approach has much greater allowance for adjustment in suspension settings, especially Camber.

For the rear suspension - Lotus originally used a live axle (or solid axle) rear suspension. 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 response. A live 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. ... Solid axle and Panhard rod on a 2002 Mazda MPV A live-axle (also called solid-axle, beam, or dead-axle) suspension is an automobile suspension that uses a single-piece axle to connect the front or rear wheels, side-to-side. ... Gasfilled Shock absorber. ...

In the early 1990s as supplies of live axles dried up, manufacturers started to introduce various independent and semi-independent designs. Most popular is the semi-independent De Dion tube, but others have also tried rear wishbones to great effect. A de Dion tube is an automobile suspension technology. ...

Tyres and wheels

Tyres that look small in comparison to those of most other cars are actually oversize for a car of this weight.

Track and wheelbase

The track is noticeably wider than that of the Austin Healey Sprite/MG Midget. The wheelbase is long relative to the length of the car and the distribution of mass. The Austin-Healey Sprite was a small open sports car designed by Donald Healey. ... Round Wheel Arch MG Midget on Autotest The MG Midget was a small sports car produced by MG division of the British Motor Corporation from 1961 through to 1979. ...

Unsprung weight

Due to the solid axle with which most (but not all) models are fitted and the very low overall weight, this is not particularly good. Again, the effect on the handling is controlled at the expense of the ride. (Ride harshness is aggravated by the lack of springs or thick cushions in the seats, which are only pads on the floor panels.)

Aerodynamics

In general, un-aerodynamic cars 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, so unless these are changed, the good handling, like the good straight line performance, is limited in speed range. It can be argued that this is not usually important in a car intended for public roads. Aerodynamics is a branch of fluid dynamics concerned with the study of gas flows, first analysed by George Cayley in the 1800s. ...

Delivery of power to the wheels and brakes

These are not unusual, beyond a rather smooth application of torque.

Yaw and pitch angular inertia (polar moment)

It is very short, and the nose and wings are of very light fiber glass. There are often no bumpers at all, for exactly this reason.

Physics favors a small car in handling, also, because angular inertia depends more on size than turning or rolling torque does.

Roll angular inertia

The body is much narrower than the track, and the wings are very light. It is about three feet high, with nothing but the roll bar (if fitted) and windscreen sticking up that high.

Position and support for the driver

The driver is upright and held in place between the transmission tunnel and side panel.

Steering

The rack and pinion steering provides a minimum of play and friction. The light weight assures light steering without power assist, even with very large tyres. The ratio is quick.

Alignment of the wheels

Nothing unusual.

Rigidity of the frame

Like racing cars of the time and the equally respected and more expensive Mercedes-Benz 300SL 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. 1955 Mercedes-Benz 300SL Gullwing Coupe from the Ralph Lauren collection 1955 Mercedes-Benz 300SL Gullwing Coupe from the Ralph Lauren collection Wikimedia Commons has media related to: Category:1955 Mercedes-Benz 300SL Gullwing Coupe The Mercedes-Benz 300SL was available as a two-seat closed sports car with characteristic...

It is a stressed skin [[6]] construction, in which the flat aluminum body panels, and especially the floor, triangulate the largely rectangular steel tubular frame structure. This gives a ridgid 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. In mechanical engineering, stressed skin is a type of rigid construction, intermediate between monocoque and a rigid frame with a non-loaded covering. ...

Mechanical details

Engines

After the English Ford flathead (L head or side valve) with 49 hp (37 kW), a BMC series A was used, then push rod overhead valve Fords of 1340cc and 1500 cc with the intake and exhaust on the same side of the head. These were often Cosworth modified; the Cosworth 1340cc "Super Seven" delivered 85 bhp and the 1500cc "Super Seven 1500" 105 bhp. These were later replaced by the Ford Kent engine, better known as the Ford crossflow, in 1600cc and 1700cc models designated SuperSprints; in their 1700cc guise, a crossflow delivers up to 135 bhp. The acceleration finally caught up to the handling when the Cosworth/Ford twin cam 1600, 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. Ford flathead V8 engine, modified for power, depicted on cover of Hot Rod magazine. ... Ford sidevalve engine in a Ford model T. Ford Sidevalve is an engine from Ford Motor Company. ... Cosworth Logo Cosworth is an automotive engineering company founded in London in 1958 specialising in engines for automobile racing. ... The Ford Kent is an internal combustion engine from Ford of Europe. ... Lotus Elan is the name of two convertible automobiles and one fixed head coupé produced by Lotus Cars. ... Coventry Climax was a British specialty engine manufacturer. ...

The latest models are the most powerful. The CSR 260 the fastest with a Cosworth tuned 2.3 L Duratec engine giving 260 hp (194 kW). The Rover K-Series engine has been replaced by the 1.6 L Ford Sigma engine with 115 hp (86 kW), 140 hp (104 kW), or 160 hp (119 kW). A 2.0 L Duratec with 210 hp (157 kW) will be used in the Superlight R400.^[5] Turbocharged MZR engine in a 2006 Mazdaspeed 6 The MZR is Mazdas latest Straight-4 engine. ... The Rover Group K-Series engine is an engine built by MG Rovers MG Powertrain division. ... The Ford Sigma is a small straight-4 automobile engine sold by Ford Motor Company as the Zetec-SE and by Mazda as the MZI. The engine was introduced in the mid-1990s and production continues through the present. ...

Frame and body

It had a front engine and rear drive like most cars of its time, with a tubular steel frame with stressed skin aluminum bodywork. The body panels were flat to avoid the expense of more elaborate aluminum bodywork. The nose and wheel arches were thin colored fibreglass. Often neither the body nor the arches were painted. It was a bit over three feet high with the top up. The track was relatively wide. The ground clearance was 5 inches to the main frame tubes, but components extended at least half an inch lower. Because the upper frame tubes were high for rigidity, there were no doors, but only removable hinged side curtains. Bumpers were not standard, as they would have degraded the very low angular inertia (polar moment) as well as the total weight. A heater could be installed.

Weight

Early Lotus Sevens weighed around 1100 lb (500 kg). Although the weight crept upward as production progressed, it remained remarkably low for a production car of over a litre displacement. Superlight production models weigh well under this and the latest high performance model reports a stunning, world class power / weight ratio in the region of 600 hp (447 kW) per metric ton or 3.7 lb per hp.

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 engine. Coventry Climax was a British specialty engine manufacturer. ...

Broken off splines from the Standard Companion estate car (station wagon) half axles of a Lotus Seven series II

Image File history File links Standard_Companion_splines. ... Image File history File links Standard_Companion_splines. ...

Problem areas

The series II had problems with its Standard Companion estate car (station wagon) rear axle and differential, however Caterham has supplied stronger parts. 1927 Standard Nine Selby Tourer 1933 Standard Ten. ... Estate car body style (Saab 95) A station wagon (United States usage), wagon (Australian usage) or estate car (United Kingdom usage) is a car body style similar to a sedan car but with an extended rear cargo area. ... Estate car body style (Saab 95) A station wagon (United States usage), wagon (Australian usage, though station wagon is widely used) or estate car (United Kingdom usage) is a car body style similar to a sedan car but with an extended rear cargo area. ...

The anti-roll bar has broken in at least one old car, but without the serious consequences that might be expected for a member that takes braking loads.

Footnotes

October 17 is the 290th day of the year (291st in leap years) in the Gregorian calendar. ... The introduction to this article provides insufficient context for those unfamiliar with the subject matter. ... October 19 is the 292nd day of the year (293rd in leap years) in the Gregorian calendar. ... The introduction to this article provides insufficient context for those unfamiliar with the subject matter. ... October 19 is the 292nd day of the year (293rd in leap years) in the Gregorian calendar. ... The introduction to this article provides insufficient context for those unfamiliar with the subject matter. ... October 21 is the 294th day of the year (295th in leap years) in the Gregorian Calendar, with 71 days remaining. ... The introduction to this article provides insufficient context for those unfamiliar with the subject matter. ... Edmunds. ... May 17 is the 137th day of the year in the Gregorian Calendar (138th in leap years). ... The introduction to this article provides insufficient context for those unfamiliar with the subject matter. ...

References

• Jeremy Coulter. The Lotus and Caterham Sevens. Croydon: Motor Racing Publications Ltd., 1986. ISBN 0-947981-06-3
• Lotus Super Seven Series II owner's manual, Lotus Components.
• Amazon list of many related books
• Lotus Seven Register [7]

External links

• http://www.r300.net Superlight R300, R400 & R500 Owners Website.
• http://www.se7en-up.co.uk Contains a comprehensive history of the 7 sports car, technical specifications, reviews and projects.
• http://www.caterham.co.uk The modern day custodians of the legend.
• http://www.lotus7club.co.uk The Lotus 7 club of Great Britain
• http://www.blatchat.com The Lotus 7 club's Internet forums
• http://www.californiacaterhamclub.com The California Caterham Club
• http://dmoz.org/Recreation/Autos/Makes_and_Models/Lotus/Seven/
• Lotus Seven Club Sweden
• US Caterham Site