Princess and Ambassador
Owners Club.
Page reprinted from March 2005 Celebratory Edition of
   Wedge World - marking the first 30 years of Wedges.







Back in March 1975 Philip Turner of Motor Magazine explained the process of how the ADO71 programme went from idea to reality.

At the beginning of the 1960s, the British Motor Corporation was still wedded to the philosophy that a well designed car of advanced engineering concept should have a life of a least 10 years, especially when 'the body design made not the slightest concession to current fashion. It is therefore not altogether surprising that although the "AD017" Austin 1800 made its public debut in October 1964, no steps were taken to design a successor until February 1970. On February 27, the then Director of sales, Filmer. Paradise, submitted a confidential memo to the members of the Product Policy Committee.

This memorandum put forward the view that the main growth prospects for the second half of the 1970s would be in the European market, especially in D class cars over 1500 cc and that the Austin-Morris Division should initiate urgently a programme for a European influenced big car to succeed the AD017. It was felt that a conventional in-line front-engined rear wheel drive car styled to meet the needs of the European market would be the answer, and that the new code name suggested for the proposed car would be Diablo.

The proposals from Marketing went up to Product Planning and Engineering who were not in agreement over departing from the trans­verse engine front wheel drive layout. Product Planning together with Sales did a full analysis of the potential market, likely volume and initial price estimate in April, 1970, and then by May, 1970, drew up a list of the main requirements in terms of dimensions, performance, trim and other details. These details were compared point to point with the equivalent specification details of the Ford Cortina, Vauxhall Victor, Peugeot 504, Audi 100LS, Renault 16, Fiat 125 and Opel Rekord. And not necessarily the models current at that time, but also against models as yet unannounced.

At this time, the 1800 version of the Diablo was still destined to be powered by the single over­ head camshaft 1750 E Series engine as used in the Maxi and the Allegro and it was hoped to have a five speed gearbox for the six cylinder versions. The specification also called for a 35 feet turning circle and 5.5 in wide rims.

Once these parameters of the design had been decided, the Package Engineers produced drawings showing the mechanical layout, the passenger space requirements, controls, luggage space, and many details. Then in June 1970, the preliminary concept came before the Product Policy Committee of Austin-Morris for approval, together with a request for permission to develop it into a full concept brochure for presentation to the Board.

Once this approval was given, action could be taken to turn the Diablo from a paper project into a car in the metal, though the first prototype was still a long way off. So far, the new project had been mainly the preserve of Marketing Sales, Engineering and Product Planning, although Finance have already been involved, for the one and only reason for making a new car is to make money, therefore the costing of the exercise is obviously vital. So very early on Finance (Vehicle Cost Control) were asked to arrive at a target cost for the new car. This they did by preparing what they call a "paper model," estimating the cost of the car part by part. They based their estimates on a complete cost analysis of the AD017 and of one or two competing models, estimating what it would have cost BL to manufacture them.

Once approval at Austin-Morris level had been given to develop the programme, the question of how and where Diablo was to be made at once arose. The two main manufacturing divisions, Power/Transmissions and Body/Assembly, now came into the picture. As the four and six cylinder engines and trans­missions were already in produc­tion for the AD017s, this aspect of continued production presented no new problems. It was confidently expected the new AD071 would sell in considerably greater numbers than the 17. Manufacturing the new body called for much more complicated decisions however. The problem initially is a two-part one, Facilities and Tooling. As a rough and ready generalisation, the Facilities are the buildings and services and the great presses that produce the body parts in sheet metal and Tooling are the dies that go into the presses. Moreover, the facilities can be used to build any model, but the tooling is specific to one model.

As yet, however, there was no body to manufacture. For young Harris Mann, the stylist, had just completed a styling exercise for the 1969 Motor Show, the BL Zanda sports coupe. On the strength of this, Harris Mann was asked to sketch his concept for a saloon car of the future press release.

 The drawing, however, attracted the attention of some of the Austin-Morris top management who said " Why regard it as just a dream car. Why not build it as a production car."

 This drawing was not to turn into a glass fibre dream car like the Zanda project. Harris engaged in sketching outer skins over the packaging requirements set out in the drawings prepared. Slowly He began to clothe the Diablo.



The drawing came at an auspicious time, for it had been decided the new AD071 would not just be a straight forward replacement for the AD017 but should go upmarket in an attempt to win sales from rival makes not merely secure repeat orders from current 1800 owners.

 From the styling drawings, a full size clay model was built for showing to the management. By November, 1970, the programme was really taking shape, for it was now possible to have a shrewd idea what the car would look like, what its engineering features would be, what its sale potential was, what manufacturing facilities would be required to make and assemble it, how much it would cost and finally how long it would take to get into production.

This meant that sufficient information was now available to put the concept before British Leyland’s main board for approval in December 1970. I had rather visualised this as a fairly dramatic occasion with a full presentation to the Board by the Austin-Morris Managing Director with slides, charts and a power­ful speech

But in fact, I am assured; it was not like this at all. The new car was but an item on the agenda, for already most members of the board knew a great deal about the project, thanks to the reports circulated by the Product Policy Co-ordination Committee which went not only to Lord Stokes and John Barber but to those members of the Board with a special interest in either Finance or Engineering or Marketing. The concept was therefore no surprise to them when it appeared on the agenda, and the giving of formal approval to the concept was almost a routine matter.

But once this approval was given, the whole programme was really on its way. So far as the car itself was concerned, some major decisions had been taken. For instance, it was decided to retain the B series four cylinder engine for the 1800 model rather than use the 1750 E series engine, for which there would be an increasing demand by both the Maxi and the Allegro, which of course was then some time still in the future so far as its public introduction went.  When the Diablo was first projected, it was expected the new car would take the place not only of the current 1800 and 2200 models, but also of the Maxi and Austin Three litre. However, further market research led to the view that the Maxi should be continued, for once the decision had been taken not to give the Diablo a fifth door—as this was felt to be not in keeping with its up-market image—then obviously here was still a place for the five-door Maxi.

 Both the Maxi and the Allegro contributed to the suspension of the new car, the Maxi through the adoption of a derivative of its front suspension layout and the Allegro through the employment not only of a specifically developed version of Hydragas suspension but also of a basically similar Allegro rear suspension layout. By late 1970 an externally normal looking 1800 was running around with the new suspension concealed beneath its skin.

The body design too, was evolving. Main inspiration for the Harris Mann shape had been the sports racing two -seater with its wedge shape, which paid dividends when wind tunnel testing began with a quarter scale model, for it was found to be exceptionally clean for a big saloon, the original models having a coefficient of 0.350.








From these models a full size glass fibre shell was built for further wind tunnel testing, which showed that the deep spoiler on the rear roof lip was creating too much down force an progressively smoothed out to reduce drag and yet give the required down thrust needed for stability. The sloping nose was also modified to pass enough air through to the front mounted radiator and reshaping the top surface of the bumper and the area beneath the bumper also played a part. One of the gains from the excellent aerodynamic shape of the car (in its final production form the coefficient is just over 0.404) is its excellent stability at speed and its lack of wind noise.

  While the exterior shape was being refined in the wind tunnel, the computers at the Cowley body engineering depart­ment were ensuring adequate clearance for the front wheels on full lock and full travel, and CAD (computer aided design tech­niques) were also used to transfer the design of the body from the full scale clay model to the sheet metal structure of pre production.

Meanwhile the costing people on the basis of their complete cost analysis were hard at work compiling the Design Cost Budget book. Known hereafter as the Green Book, it listed the cost of every part, and had to be signed by the engineering, purchase and manufacturing people responsible for that part to attest that they had accepted its cost as their target.

Important decisions were also being taken on where the AD071 would be made. It had been de­cided that the new car would take the place at Cowley of the body and assembly facilities used to manufacture the 1100-1300 range, which of course would be phased out once the Allegro was in full production at Longbridge. Moving 1800-2200 production from Longbridge to Cowley would then have the additional advant­age of enabling Allegro production to be expanded in the space and facilities thus made vacant. The eventual production volume for facilities planning was set at 2000-3000 AD071s a week from Cowley.

  When styling was finalised there was very close collaboration between the men responsible for the design and engineering of the body and the tooling engineers.    Process engineers, facility engineers and tooling and facility engineers were all involved from the moment when the styling was finalised, and this very tight co-operation, much closer than on any previous BL model, this meant that very few modifications had to be made to the design of the body when tooling up for it began. The four main stages in making the body are the production of the numerous pressings, the weld­ing together of the individual pressings into sub assemblies, then the putting together of the sub assemblies to form the com­plete but un-painted body and lastly the final assembly when the body is united with its mechanical and suspension components. The first decision to be taken concerned the pressings and whether they were to be produced at Swindon, Castle Bromwich or Cowley. It was decided that as far as possible the panels forming the outer skin of the body should be pressed at Cowley where the body was to be put together, for these skin panels are the ones most susceptible to dam­age when being transported around the country. Once the deci­sion had been taken as to where a panel should be made, then it could be allocated to a particular line of presses, always assuming that this did not mean that new presses were then required, for there is a delay of 2 years between the placing of an order for a new press and its delivery and installation. Then came the design and manufacture of tooling to suit a particular type of press. British Leyland make all their own press tools, and the majority of the body and assembly jigs and fixtures, but even so, it takes 12 months to make the dies. In April 1971, the full specification was finally decided. Almost from the beginning, it had been decided there would be both Austin and Morris versions, with modified front and rear ends to distinguish them, but the original decision that there would not be a Wolseley version was later reversed. This meant that equip­ment for the normal and highline models had to be decided upon, plus additional equipment for the even more up-market Wolseley.   Quite apart from decisions about major items such as whether a brake servo should be fitted as standard, each detail of the equipment had to be argued over. Was its extra cost going to be justified by more sales? Or would the addition it made to the selling price have an adverse effect?

By June/July 1971 manufactur­ing plans were complete. More than £15 million was to be spent on the body and assembly plants at Cowley. Sub assemblies in the body plant were to be put together in an area previously engaged in making the Rover coupe, and a massive new weld­ing press was to be developed in collaboration with BL engineers for producing the main floor unit. This would then be transferred to the main body assembly line, which the new car was to share with the Maxi. The body sides would be assembled separately in massive jigs, which are then clamped, into position on each side of the floor unit and the body sides are spot welded to the floor.

This method of body assembly rather than feeding floor, sides and roof into one giant assembly fixture was chosen for its flexi­bility and because it eliminates the delay while the various units queue up.

Over the other side of the Oxford Eastern by-pass even more drastic reorganisation took place in Cowley North Works. The five relatively short assembly lines gave rise to a very congested working environment, and as only two were currently in use, one for the 1100/1300 range and the other for the Maxi range, it was decided to rip out the unused lines and replace them by extend­ing the two lines, thereby giving more production room, wider aisles, and greatly improved working conditions. The work would mean a complete rearrange­ment, with much civil engineering work to accommodate the revised layout, including demolition of the old GK paint shop.

In August 1971 the British Leyland Board gave its final approval to the body styling sign off and as a consequence of this also to the ADO71 programme. This signified the commencement of the work of transforming the complete specification into a real vehicle, since no finance can be committed for either manu­facturing facilities or tooling until British Leyland Board approval!

Definite targets had by now been set for the price, cost and volume, to see that the car remained on target, the estimators monitored the design cost to make sure each part did not exceed the cost laid down for it in the green book. These estimators are highly qualified engineers who are not only well grounded in design and production engineering, but also know the capabilities of the suppliers who in many cases will be responsible for manufacturing and supplying individual items as well as complete assemblies. The estimators realise there would be some overrun to the original green book costs because initial estimates may not have been based on complete information. But the art of the estimator lies in finding enough savings on other parts by value analysis and value design to ensure that the savings balance out the overruns

By September 1971, some fairly strange 1800s might have been glimpsed going in and out of the experimental department on test they were the simulators, ADOl7’s with ADO71 front styling and front suspension. The simulators were followed by four SEPs, semi-engineered prototypes, which are hand-built prototypes built in the body experimental shop and represent the design stage reached at that time. An enormous amount of test running was completed with these cars which were followed by 12 FEPs, fully engi­neered prototypes. These are still hand built but are made from the production drawings and incor­porate all the lessons learned from the SEPs. Much of the test running was carried out in Italy, but the United States and Canada were also used. The United States has the Arizona Desert to give very high temperature conditions and Canada fills in at the opposite end of the temperature scale, thanks to its freezing winters. One problem is that all the test cars run for the first two years are overweight; owing to the camouflage they have to carry.

In July 1972, the complete re­fashioning of the Cowley Assembly North Works began to install the facilities for the new model. It was a pretty dramatic business, for production of the then current models was maintained in spite of rebuilding going on ail around, and that production was maintained, this was due entirely to the tremendous co-operation of all the workers and the super­visory staff.







Once the facilities were com­plete and the tooling available, test runs were made on the presses and the body assembly fixtures. Usually only a few panels are pressed, but the marrying of the panels on the ADO 71 is much more accurate than on any previous BL model and to secure this accuracy more than 50 examples of many panels were produced during testing. This emphasis on quality applied not only to the body but also to all its fittings, which were all the sub­ject of a very intensive investiga­tion and test programme before being finally cleared for produc­tion.

 A tremendous effort too, was made to ensure the body had no water leaks, this point having received particular attention right from the design stage. In November 1973 the pre-production cars with the majority of their parts production- and not hand-made items went on test, then in August, 1974 the Pilot cars came down the production line, fol­lowed in November 1974 by the first volume production cars.

 Ever since, the Cowley directors have been taking five cars off the line at random every week and driv­ing them to make quite sure the production cars are up to the very high standard set for this model.

And so to March 26, 1975, when no longer the ADO 71 or even the Diablo, but the 18/22 series went on sale to the public.

 Jim Inshaw.  March 2005.