Lotus Components: Lotus and de Dion: The French Connection

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 functional and beautiful in their own right. They formed part of a complementary whole.

In this series we examine:-

  • significant Individual components from all the marques
  • Briefly explain their role /contribution /evaluation
  • Analysis 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 Optional Extra-Compact Disc
  • Lotus 7:20
  • Lotus Seven & Missing Link

Advantages of Independent Suspension

Singh Reyat summarizes the advantages as follows:-

  • Reduced unsprung weight and hence improved ride and better road holding while cornering and breaking
  • The frame and body do not tilt but remain horizontal and the wheels vertical when the vechicle encounters a road hump
  • The wheels being sprung independently , springing movement of one wheel is not transmitted to the other side
  • Provides a greater degree of vertical/ springing movement
  • Diminished wheel wobble and steering tramp
  • Provides scope for the use of springs of greater resilience giving much better springing action than most rigid axle vechicles

Sprung and Unsprung weight

Summarized by R.Singh as:-

“The unsprung weight should be kept as low as possible as the reduced unsprung weight results in obtaining a better ride “

On the subject of Independent Suspension systems he comments:-

“In independent suspension, there is no axle beam running below the frame like the conventional suspension system, suspension for each wheel is an independent unit and is free from the effects of one another, the linkages used in the construction of this suspension compromise the basic features of the suspension.

The following types of independent suspension system are applicable to automobiles:-

  1. Wishbone arm system
  2. Trailing link system
  3. Sliding pillar system

De Dion Tube

Independent Rear Suspension


Figure 2.Editors sketch of early de Dion car fitted with their own rear suspension arrangement.


“Although independent rear suspension are not widely used, the different systems in use may be briefly reviewed:

The conventional “life “axle that this an axle casing containing the final drive gears , differential and axle shafts –is a relatively heavy unsprung unit .attached to leaf springs , torsion bars or coil springs , it has a tendency to bounce on poor road surfaces ,adversely affecting road holding and stability. Moreover, the engine torque reaction tends to lift the right hand wheel [viewed from the rear] off the ground, causing wheel spin on slippery surfaces

The de Dion type rear suspension greatly reduces the unsprung weight by mounting the differential casing on the chassis frame and driving the wheels through two short , universally jointed shafts .the rear wheel hubs ,however are carried on an axle beam to which the suspension members are attached.it is a common fallacy to mistake de Dion suspension for true independent rear suspension ,it will be obvious ,however that this is not the case since the wheels are linked by the axle beam

From the net:-

“De Dion suspension uses universal joints at both the wheel hubs and differential, and uses a solid tubular beam to hold the opposite wheels in parallel. Unlike an anti-roll bar, a de Dion tube is not directly connected to the chassis nor is it intended to flex. In suspension geometry it is close to the trailing beam suspension seen on many front wheel drive cars, but without the torsional flexibility of that suspension.



The de Dion tube was named after Comte Jules-Albert de Dion, founder of French automobile manufacturer De Dion-Bouton. The tube, however, was invented around 1894 by co-founder Charles Trépardoux for use on the company’s steam tricycles.[3]

Advantages and disadvantages


  1. Reduced unsprung weight compared to the Hotchkiss drive (live axle), since the differential and half-shafts are connected to the chassis.
  2. Unlike most fully independent suspension there are no camber changes on axle loading and unloading (or rebound). Fixing the camber of both wheels at 0° assists in obtaining good traction from wide tires and also tends to reduce wheel hop under high power operations compared to an independent suspension.
  3. The choice of shock absorbers and springs is made easier.[2]
  4. The two wheels may be individually aligned, allowing for independent camber (vertical) and track (horizontal) alignment.


  1. A pair of CV or universal joints are required for each wheel, adding complexity, cost, and weight.[2]
  2. If coil springs are used then a lateral location link (usually either a Panhard rod or Watt’s linkage), plus additional torque links on each side (five link suspension) or a combination of lower trailing links and an upper transverse wishbone are required. None of these additional links are required if leaf springs are used, but ride can be compromised due to the leaves having to do double duty as both locating links and springs. The torque links are not required if the setup uses in-board brakes, like in the Pegaso 1502, Rover P6 and Alfa Romeo type 116 (and derivatives), as the wheels do not transmit torque to the suspension.
  3. Sympathetic camber changes on opposite wheels are seen on single-wheel suspension compression, just as in a Hotchkiss drive or live axle. This is not important for operation on improved surfaces but is more critical for rough road or off road use.”

De Dion: Lotus application

Using the Lotus book as reference we note the main models to use de Dion rear suspension as:-

  • Mk .VIII:”de Dion axle with transverse coil spring/ piston dampers”

In the Lotus Story –Part 4 Colin Chapman stated:-

“De Dion type rear suspension was fitted with inboard brake drums and the suspension medium was transverse coil springs .this form of rear suspension was chosen mainly to keep down wheel spin and to reduce unsprung weight, a “live” axle tends to lift under wide throttle openings, as torque reactions tends to lift one rear wheel to induce wheel-spin. This is obviated with the de Dion type axle due to the “diff” housing being bolted up solidly to the frame, the drive was taken out to the rear wheels by two separate, short drive shafts”

Whilst Smith adds:-

At the rear a de Dion type of axle was used ,in conjunction with a transverse helical spring held in tension ,an damped b Armstrong piston –type units .the brakes were fitted inboard ,each side of the differential housing ……….”

  • Mk.IX: de Dion or Ford Ten axle with coil spring/dampers.

“Lotus Mk.IX Competition Car, Autocar, 1955 quotes:

“the rear wheels are supported by a de Dion tube and are therefore, not fully independent .the axle tube is swept behind the final drive unit and is made from 3 inch diameter 16 swg mild steel tube .each end of the tube merges into a fabricated housing provided with two opposed conical seatings .into this fits an aluminium casting containing the hub and race assembly ………..which makes an ingenious and extremely light unit …………..”

  • Mk.X:ditto
  • Eleven: de Dion axle with twin radius rods , coil spring/dampers


Figure 3.Editors sketch drawing of de Dion of rear suspension in Lotus Eleven

Further details of the Eleven set up are provided by Smith:-

“At the rear a de Dion layout was used which saved 10 valuable unsprung pounds from the layout used in the Mk.IX. The tube was pierced to allow the half shafts to pass through , so giving them much greater length and less deflection for the universal joints .the short tubular shafts were still extensions from the Rudge –type hubs , but now carried on pair of taper roller races in a light alloy housing .as earlier a pair of radius arms located the axle on each side , but now one of them was triangulated into an A-frame to absorb lateral forces .ultralight hydraulically operated 9.5 inch Girling discs were fitted out board at the front and inboard at the rear , the calipers of the rear being carried ahead of the axle to reduce overhand loads ……….a horizontally mounted hand brake operated the rear calipers through inner and outer cables…….”


“the de Dion rear suspension of the Le mans car has been completely redesigned and the tube diameter increased to 3.25 inches .he outboard universal joint is now inside the tube instead of being located in the conventional manner .the new arrangement has meant a valuable saving here of 15 lbs. ,unsprung weight .the rear wheels are located longitudinally by parallel trailing arms , whilst a diagonal bracket has been introduced on the off-side which provides the equivalent of a Panhard rod of 64 inches in length……..”

Learning 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 centre 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:-

  • Was there a viable alternative to the part under consideration?
  • If, 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

Editors sketch of Lotus Eleven with De Dion rear suspension set up

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”

In this instance we feel the following might be appropriate: –

  • De Dion and the French Revolution: Keeping the wheels on the Ground
  • De Dion and the Wheel of Fortune
  • Chapman improves handling: Going in the French Direction
  • De Dion and Lotus: The French Connection
  • De Dion and how Lotus cut corners
  • De Dion: Chapmans Cornerstone

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 where we expand on the manufacturer’s history, products and list more extensively in which their components were used. The relationship between Lotus and 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.

Forms of de Dion suspension have been used on Caterham’s.


Legend of the Lotus Seven.Ortenurger.Osprey.1981.

ISBN: 0850454115

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

ISBN: 3822863106

Lotus: The First Ten Years.Smith.MRP.1958.

Lotus Sports Racers. Unique books

ISBN: 1841554308

Practical Automobile Engineering Illustrated. [Ge.Editor, S.Abbey]Odhams.1959

The Automoile.Singh Reyat.Chand.2011.

ISBN: 8121902142

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.