Compact Disk- an optional extra? Lotus Seven -The Front Disc brake  

Lotus Components: A Series in Many Parts- The Contribution of Components in Colin Chapman’s Iconic Automobile Design


Figure 1.Image taken from the net.


Lotus cars sold

They were bought for their:-

  • Performance –road or track
  • Driving pleasure
  • Reputation and image
  • Aesthetics
  • Symbolism
  • Owner identification /personality extension etc.

All the above were integrated within a total framework design.

The above list is heavily dependent on a select group of components [either bought in proprietary or in house manufacture] that delivered the desired outcomes and met strict criteria.

Many of these components often contributed significantly to the overall aesthetic, many are extremely function and beautiful in their own right .They formed part of a complementary whole.

In this series we examine:-

  • Significant Individual components from all the model range
  • Briefly explain their role /contribution /evaluation
  • Analysis of form and function with regard to their integration
  • Provide sketches or photographs to illustrate
  • Learning opportunities

Understanding Lotus’s use of proprietary parts provides invaluable learning opportunities not just historical but right up to the present day. These lessons are not just applicable to automotive engineers/ designers but to the wider Industrial /Product Design professions.

The Skillful and creative adoption, absorption and integration of components was a powerful factor in the Chapman design methodology and contributed significantly to both competition and commercial success. It also feed his ability to mutate parts and materials to his desired ends.

The use of components is a fundamental skill of the Industrial Designer and the direct provision of added value.

Subscribers might like to see related A&R series:

  • “Rear View Mirror”
  • Lotus Power plants
  • Make or Break
  • Particles in suspension
  • Lotus Seven – various including aesthetics
  • Lotus Seven –brochures
  • Girling [Lotus sponsor ]

Role of Brake Component

For very basic but fundamental definitions Singh Reat provides some useful comments and calculations.

He states:-


These are mechanical devices which use the force of friction to overcome friction. The brakes in an automobile stop it while in motion and also hold it from rolling when not in motion.

When the brakes are applied on a moving vehicle, the kinetic energy or energy of motion of the vehicle is transformed into heat generated by the friction between the brake lining and drums .The heat generated is dissipated into the surrounding air.

Breaking force.

The breaking force is equal and opposite to the linear inertia on the vechicle.Neglecting retarding forces caused by rolling ,air  and gradient resistances , the force required to stop a vehicle is dependent on the weight of the vehicle and the deceleration rate or rate at which it is stopped.

Weight transfer during breaking. If maximum deceleration is to be achieved, the braking effort of each wheel must have the best possible relationship to the weight of the wheel. This is required due to the fact that during deceleration , there is a change in weight distribution  which is proportional to retardation .For  a given deceleration , the ratio of height of CG to length of wheel base determines the extent of weight transfer…………..

Brake efficiency.

It is the ratio between the retarding force and the weight of the vehicle .It is expressed as a percentage……….

Disc Brake

It consists of a disc held between two pads .The disc is attached to the axle in lieu of brake drum. The rotating disc is held up through the frictional force exerted by the brake pads. The action of brake pads is similar to the action of caliper brakes in an ordinary bicycle. It is due to this fact that this brake is known as caliper brake…………

Handbrake or parking break

This break is operated by a hand lever and is used to hold the vehicle while it is stationary. It is used during parking……….it’s also used in emergency when the service brake fails or proves ineffective.

Brake effectiveness .The following factors contribute to the effeteness of the brakes:-

  • Area of brake lining
  • Amount of pressure applied
  • Radius of drum
  • Radius of car wheel
  • Coefficient of friction of breaking surfaces
  • Coefficient of friction between tyre and road surface

Factors controlling the stop of an automobile:-

  • Speed and load
  • Road surface
  • Tyre tread
  • Gradient
  • Number of wheels breaking
  • Coefficient of friction of breaking surface
  • Pressure applied by leverage
  • Pressure applied through energization
  • Weight transfer
  • Breaking force of engine

Lotus Seven Context

Coulter Comments

“Jack Richards Competition secretary of Club Lotus bought an early Seven built to a specification similar to Edward Lewis’s car, with Climax engine, de Dion rear suspension and disc brakes.

Tested by Sports Car & Lotus Owner in April 1958 it was described as a “one in a million sports car” .It was beautifully prepared with extensive chroming and polishing of the 80 bhp Climax engine. Top speed of this formidable little car was above 100 mph mark. The front suspension was standard S1 Seven, but with discs brakes. The discs at the rear were inboard”

Coulter features photographs of this specific car registered TBY 484.

Weale Comments

“Early production series 1 cars employed twin leading shoe 9” diameter Girling drum brakes at the front…………..Front disc brakes were fitted to certain series 1 cars to special order, but did not become cheap enough for Lotus to supply them as standard equipment for the Seven until suitable ones appeared in the Triumph range and these 9” discs were fitted to all except the most basic series 2’s from 1963.”

Ortenburger Comments

The editors paraphrase that some series 1 cars that were special versions were fitted with a Girling alloy caliper disc brake at the front

Lotus and Sports car Owner, 1958

Writing in an article entitled “This One is Different” of Seven [TBY484] the testers observed:-

“Faultless Brakes”. We can find no fault in the breaking department –although some disc brakes on these cars have been found to grab at times. Firm pressure ion the pedal is necessary but braking effort is very progressive. There was no squealing and no locking of wheels except under heavy pedal pressure at slow speeds.”

Drawing: Form, Function and Aesthetics

Information from the net assists with an appreciation of form and function:

“A disc brake is a type of brake that uses calipers to squeeze pairs of pads against a disc in order to create friction that retards the rotation of a shaft, such as a vehicle axle, either to reduce its rotational speed or to hold it stationary. The energy of motion is converted into waste heat which must be dispersed. Hydraulic disc brakes are the most commonly used form of brake for motor vehicles but the principles of a disc brake are applicable to almost any rotating shaft.

Compared to drum brakes, disc brakes offer better stopping performance because the disc is more readily cooled. As a consequence discs are less prone to the brake fade caused when brake components overheat. Disc brakes also recover more quickly from immersion (wet brakes are less effective than dry ones).

Most drum brake designs have at least one leading shoe, which gives a servo-effect. By contrast, a disc brake has no self-servo effect and its braking force is always proportional to the pressure placed on the brake pad by the braking system via any brake servo, braking pedal, or lever. This tends to give the driver better “feel” and helps to avoid impending lockup. Drums are also prone to “bell mouthing” and trap worn lining material within the assembly, both causes of various braking problems.

The brake disc (or rotor in American English) is usually made of cast iron, but may in some cases be made of composites such as reinforced carbon–carbon or ceramic matrix composites. This is connected to the wheel and/or the axle. To retard the wheel, friction material in the form of brake pads, mounted on a device called a brake caliper, is forced mechanically, hydraulically, pneumatically, or electromagnetically against both sides of the disc. Friction causes the disc and attached wheel to slow or stop.

On automobiles, disc brakes are often located within the wheel.

The development disc-type brakes began in England in the 1890s, but they weren’t practical or widely available for another 60 years. Successful application required technological progress, which began to arrive in the 1950s, leading to a critical demonstration of superiority at the Le Mans auto race in 1953. The Jaguar racing team won, using disc brake equipped cars, with much of the credit being given to the brakes’ superior performance over rivals from firms like Ferrari, equipped with drum brakes. Mass production quickly followed with the 1955 Citroën DS.

Disc sketch

From all our observations it can be understood that the mechanical properties of the disc brake was a perfect complement to Chapman design methodology.

The design, appearance, materials etc. of the Girling disc brake was performance orientated.

It complemented the overall design and fitted into an integrated hierarchy of design imperatives.

Furthermore it was simple in operation, accessible and easy to service. It simply looked and did exactly what it ought. Studied in conjuction with other suspension components [see A&R article “Particles in Suspension” it’s easy to understand that Chapman and his colleagues at Lotus took care to select and adopt componentry that was first most functional but also sympathetic to aesthetic they sought.

Within this there are important lessons for all designers .The disc brake would have contributed to sales. Although expensive and perhaps not massively an improvement it was of the moment and certainly conferred on the Seven this indelible image of professional sports car in thought, detail and aspects of execution.

Lotus Seven Series 1: Production Numbers

Taylor in the “Lotus Book” suggests that 242 SI cars were produced c 1957-1960.

Learning/ Evaluation Opportunities

Our learning /educational opportunities are intended to be challenging thought provoking and requiring  additional research and/or analysis.

These opportunities  are particularly designed for a museum/education center location where visitors would be able to enjoy access to all the structured resources available in conjunction with any concurrent exhibition.

In this instance we suggest the following might be appropriate:-

Understanding the potential of componentry particularly proprietary items provides some of the following learning:-

  • Describe the differences between drum and disc brakes
  • Explore relationship of chapman design methodology , handling and weight to breaking
  • Was there a viable alternative to the part under consideration?
  • Is what might it have been /cost?
  • What is the importance of ergonomics  and how does it influence modern automobile design?
  • Does excessive safety/ and or ergonomics impact negatively on aesthetics
  • What is the impact of standardization of platforms through mark ranges and indeed shared with other manufacturers? Could uniformity ultimately impact on sales even if economies of scale improved?
  • Enumerate Lotus bought in components
  • How has mass production and proprietary parts assisted the specialist car market?
  • Produce an engineering drawing of a selected component and consider the specification of the materials and assembly process, costs and volumes
  • Explore an enumerate components used in other Industrial Design fields

Exhibitions, Education and Economics

In the museum context the editors believe that commercial considerations are both necessary and complementary with its educational objectives.

For these reasons our suggested outline Business Plan includes provision for promoting products and services which share Chapman’s ideals of mechanical efficiency and sustainability. In addition we propose merchandising that explain and interprets the social and cultural context of Chapman’s designs in period. It’s suggested there will be catalogue for on line purchasing.

In particular we consider that there is considerable opportunity to host exhibitions that display componentry in its original form, its manufacture and the eventual adoption, incorporation into Lotus cars.

Such exhibitions provide the chance to further explore the educational skills a sets offered in Learning Opportunities. Additionally it’s possible to explore how components were and are mutated into other design fields and relate to current practice. The technology and computerization offer many interactive experiences related to learning opportunities that will stretch imagination and conceptualization .Furthermore such experiences and experiments can be structured to relate to other branches of Industrial/Product Design.

They are complementary to the possibility that the museum /education center can fulfill the role of the “Exploratory -Laboratory”

Conclusion: “The whole is greater………”

Chapman’s design and manufacturing methodology rather confirms the adage that “the whole can be greater than the sum of the parts”.

It’s an interesting an important study to consider deployment of components. It contributes to aesthetics, assembly economics and sales [attractive components/ known accepted performance and servicing ability etc.]

It is equally and mutually relevant and beneficial to the component manufacturer.

Chapman and his colleagues often took the best / most appropriate mass produced item and almost reinvented it in its service to design objectives. In this manner many components acquired a new status and indeed their aesthetic was enhanced surrounded by the Chapman conceptual whole.

It’s also extremely significant how many of these components were also used in Lotus competition cars. This created a powerful dynamic and interrelationship. Many components:-

  • Performed well in competition gaining beneficial publicity and sales
  • Both the component and racing reputation carried through to road cars and assisted sales
  • The component manufacturer gained disproportionate publicity and assisted products sell in other applications
  • All together a beneficial spiral was commenced. Publicity of the era [see dedicated articles on each sponsor / manufacturer] often opted to highlight the Lotus dimension in publicity material. In fact there was a powerful synergy.

Subscribers are directed to A&R dedicated article on Girling where we expand on the manufacturer’s history, products and list more extensively in which their components were used. The relationship between Lotus and Girling is substantial and worthy of close study and has lessons for Engineering, Industrial Design and Manufacturing disciplines.

Along the way it’s possible too to study the wider British motor component industry and how it has helped foster the specialist car manufacturers.


Subscribers are directed to our articles on Lotus Seven that contain an extensive bibliography. Of special interest are:

The Magnificent Seven.Rees.Haynes.2007.

ISBN: 9781844254101

Lotus & Caterham Seven.Tipler.Crowood.2005

ISBN: 1861267541

Lotus Seven.Weale.Osprey.1991.

ISBN: 185532153X

Lotus Caterham Seven. Unique Books.

ISBN: 1841553778

The Lotus & Caterham Sevens.Coulter.MRP.1986.

ISBN: 0947981063

Lotus and the Independents.Ortenburger.Coterie.2004.

ISBN: 1902351126

The Automobile.H.Singh Reyat.Chand.2013.

ISBN: 8121902142

Industrial Design A-Z.C&P Fiell.Taschen.

ISBN: 3822863106

Please note the editors of the A&R attempt to give the broadest spectrum of references but not all are available for consultation in an article. However by noting their existence it may assist students in their research.

*Items in italics non A&R library books.