Revolutionary New British Small Cars

The British Motor Corporation’s Austin Se7en and Morris Mini-Minor Rival Continental Designs In Respect of Passenger Accommodation, Performance/Economy and Originality; 848 c.c. Four-cylinder Water-cooled Transverse Engine, Front-Wheel Drive, Sump-located Four-speed Gearbox, All-Independent Variable-Rate Rubber Suspension and Full Four-seater Two-door Saloon Body in a Car Priced at Under £500 inclusive of p.t.

The greatest praise and commendation must be accorded to the powers behind the British Motor Corporation for allowing Alec Issigonis and his design-team to take a clean sheet of paper when planning a revolutionary small four-seater saloon car, which is now announced, and in production, after development work and an exhaustive testing programme extending over a period of some eight years. Ever since the end of World War II Motor Sport has been pressing repeatedly for fresh thinking on the part of British automobile designers and engineers, so that British cars should not lag behind Continental makes in which abolition of the propeller shaft (and in some cases of the cooling water), all-round independent suspension, horizontally-opposed cylinders and low weight have long been desirable features. In persuing this policy I left myself wide open to criticism that I was anti-British, possessed substantial investments in foreign antomobile factories, was on the Wolfsburg payroll — none of which is true! All I could do in reply was to affirm that I am in control of a motoring, not a political, paper and that if and when worthwhile new cars emanated from British factories I would accord them equal publicity and praise.

This year the Triumph Herald arrived as a brilliant new model in the one-litre family-car class, with i.r.s., elimination of greasing points, many safety factors and a taxi-like turning circle, features acclaimed with enthusiasm by Motor Sport, culminating in a detailed, unbiased and analytical road-test report in the July issue.

Now the British Motor Corporation has gone a step further, in a rather different class, with its completely revolutionary and eminently practical Issigonis-conceived new small car, made in two versions as the Austin Se7en and Morris Mini-Minor, but virtually to be regarded as one model technically, known as ADO.15, differences being confined to radiator grille style, colour shades and interior trim.

The General Conception

This vitally important new B.M.C. model is not only a completely fresh conception of small car design, but it is offered at a sensationally modest price. Under these circumstances it is difficult to see how sales of Continental small cars can be maintained in this country and America. Since the war there has developed a growing home and United States demand for cars which are “different,” which embody items of specification rendering them interesting to own and comfortable and economical to drive, and if a high price, brought about by adding Import Duty to basic cost, has been involved this has not mattered to the bulk of these Continental car “fans.” With the new Austin Se7en and Morris Mini-Minor costing not only far, far less than these Continental invaders but less than all other reasonably-sized British vehicles with the exception of the outmoded Ford Popular, and being essentially a practical approach to the unchangeable problems of transporting four adult persons in comfort and safety, they surely cannot fail to deal a knock-out punch to Continental-car sales, which will now presumably revert to the pre-war “drop in the bucket,” kept going by a few fanatical enthusiasts for particular foreign makes and more definitely by the especial merits of, for example. air-cooling, rear-engines and low-speed power units in particular circumstances.

Admittedly the “proof a the pudding is in the eating,” but from what I have seen of this new B.M.C. small car it is likely to fulfil this prediction — when it was first shown, to a select party of experts, there were certainly some who became so enthusiastic they seemed almost prepared to eat what was set before them and brief driving experience certainly confirms the maker’s claim that these new “puddings” set completely revised standards of safe handling.

These Austin Se7en 850s and Morris Mini-Minor 850s also seem to belong to a new class of family vehicle — dimensionally they are very small — in fact mini — cars, but generous accommodation for four persons and the good performance to be expected from a high compression 850 c.c. engine propelling some 11½ cwt. of motor-car makes them serious rivals of existing small cars of up to 1,200 c.c. Moreover, with tuning kits which are available from specialist sources and their revolutionary cornering power these new cars should make a great impression amongst sports-car drivers and rally competitors.

When I had revealed to me the intimate details of the new Issigonis design I listened with an unbiased mind to the reasons why the specification used was decided upon. I am conscious that only after an extensive road-test can an opinion be expressed as to how successful the B.M.C. has been in its effort to offer an extremely low-priced, entirely new small family car. I shall not overlook the need to take the car into slimy fields, up steep hills and through deep water splashes before bestowing praise or criticism on this sensational front-drive, transverse-engined, all-independently-sprung vehicle. I have every reason to believe that as soon as possible the B.M.C. will place a car at this paper’s disposal for prolonged road-test and in the meantime I can only remark that I am exceedingly impressed with the new car after examining it carefully and driving it on a test track.

Although no manufacturer makes public the findings of the experimental department, the B.M.C. makes no secret of the fact that many experimental models were built and tested before the present specification was adopted. I believe these included a decidedly unconventional and compact engine and certainly vehicles with two-cylinder air-cooled power units and with pneumatic suspension, etc., were tested exhaustively before being discarded in favour of the present layout which, and this is significant, although refreshingly new, does incorporate an engine and other features, such as gearbox internals, front suspension wishbones and rack-and-pinion steering, already well-proved in existing, B.M.C. cars.

Issigonis Genius

Alec Issigonis put a transverse-engine f.w.d. power unit into a Morris Minor (another of his brain-children) for experimental purposes as long ago as 1951. I believe I am correct in saying that, as in the case of the Volkswagen, the new vehicle owes something to military requirements. Issigonis explains that although he has designed a very small car it has interior dimensions for four bulky adult humans. He uses water-cooling not only for quiet running but even more so because he wanted a compact power unit to make possible this generous passenger accommodation in a mini-size car and he regarded the ducting and fan necessary with air-cooling as being too bulky for his purpose. Another reason for the water-cooled engine he gives as the desire to gain economical petrol consumption by using high compression-ratios — the present compression-ratio is 8.3 to 1 and Issigonis says he would like to go to 9 to 1. A further contribution to good petrol economy is the fact that the reasonable sized engine is able to pull high gear ratios — top gear is 3.7 to 1.

The ultra small road wheels and highly ingenious suspension system he explains by saying that with four passengers in an 11½ cwt. car it was essential to adopt new suspension rates if proper standards of road-holding and comfort were to be achieved and that, on a commercial basis, rubber provides the only possible harnessed variable-rate medium. Pneumatic suspension he dismisses as involving complication, including an engine-driven compressor, and giving rise to condensation problems, etc. The clever suspension of the ADO.15 is a Moulton Developments product conceived by Alec Moulton, and Dunlop made tubeless 10 in. “Gold Seal” tyres for the car.

Apart from his generally new approach to the problems of a truly economical, decently fast four-seater small-car, Issigonis displays further genius in his treatment of more minor factors. Thus to employ the rubber-cone suspension units it became necessary to evolve ball-joints capable at taking the enormous loads represented by multiplication of wheel movement from the tiny movements permitted at the rubber cones. So effectively does this suspension function that the dampers, although fitted, do very little work and are very lightly loaded. Then, although neither Renault nor Fiat adopted transverse engines in their economy cars, study of the f.w.d. Lloyd may have pointed the way to this layout. But in incorporating the gearbox in the electron engine sump and making the same lubricating oil serve both, Issigonis devised another space-saver. Again, to conserve space he wanted the smallest possible radiator and fan and it is surely pure genius that he used a front-wheel arch as the radiator outlet because this is also aerodynamically a point of low pressure, using the fan to push air through the radiator, aided by this extractor effect, instead of sucking air from it. The adoption of a front transverse engine and front-wheel-drive to eliminate the propeller shaft does not involve lubrication of the universal joints in the drive shafts, a frequent source of attention in other f.w.d. cars, because self-lubricating Rzeppa constant-velocity inner and B.M.C. patented resilient inner couplings are used. There are, however, some vital grease points about the car, so in this respect the Triumph Herald retains a significant lead. Front-drive does not, in the case of the ADO. 15. result in a poor turning circle, for prominence is given to the ability of the car to park in a kerb space of only 11 ft. 6 in.

Issigonis literally designed the new car round four people; equally ingenious is the manner in which he has contrived exceptional stowage space for luggage (boot capacity, closed, 5½ cu. ft.) and oddments without encroaching on the comfort of the occupants.

Testing the ADO.15 Project

After evolving the minimum size of car for four persons to obtain economy of operation and low first-cost consistent with reasonable, indeed, sparkling, performance and endowing it with new standards of comfort and safety, particularly the latter, the B.M.C. set out to convince themselves that they had a sound proposition. To begin with, two ADO.15s were driven at very high average speeds over little-used British roads, each covering over 50,000 miles. The rubber suspension units were reported to have suffered negligible wear and the B.M.C. engineers have not yet found a means of destroying them!

Several cars were then taken on prolonged endurance tests in France, Spain, Portugal, Switzerland, Norway, Sweden, Denmark, Germany and Italy, in mid-winter and again in tropical summer. The new suspension with a “wheel at each corner,” and low c. of g. showed up well on ice and the cars refused to overheat in summer. Indeed, Issigonis tells us that in Spain, where a very high ambient temperature was experienced, it was found satisfactory to replace the export six-bladed cooling fan for the normal four-bladed variety and this economy of fan size will enable quieter fans to be evolved for production cars, this being the noisiest part of the power plant. Early production models were subsequently taken on the Continent for further testing.

The Specification in Detail

The engine is virtually an A-series B.M.C. four-cylinder o.h.v. unit with shortened stroke to give dimensions of 63 by 68 mm. (848 c.c.). It has a compression-ratio of 8.3 to 1 and develops 38 b.h.p. (34 nett) at 5,500 r.p.m., when piston speed is 2,460 ft./min. 128 lb./sq. in. b.m.e.p. is developed at 2,900 r.p.m. An HS2 semi downdraught carburetter is fed from a 5½-gallon tank in the near side of the boot by a PD-type S.U. rear-mounted electric pump. Because of the engine’s front transverse location the water-proofed distributer and plugs and the dip-stick are readily accessible. The radiator is set laterally on the near-side with the four- or six-bladed fan between it and the engine.

The drive goes via a hydraulically-operated 7-in. single dry-plate clutch to a four-speed and reverse gearbox incorporated beside the crankshaft in the magnesium-electron eight-pint sump. The three upper ratios are synchronised, the gears are changed by a long central floor lever and the gear ratios are 13.658, 8.177, 5.316 and 3.765 to 1. The final drive is through helical spur gears, universal joints and open shafts to the front wheels, the final drive being in unit with the engine and gearbox.

Two sub frames are used, the front transverse one carrying the complete power pack and i.f.s., the rear one the i.r.s., these frames being united by the rubber-mounted mono-construction body. Front suspension is by upper and lower steel-forged wishbones attached to swivel-pin hubs by ball joints, with vertically-mounted rubber-cone suspension units, the cones being in compression under load and tension as the wheels fall. The spring rate is automatically variable and damped by strut-type shock-absorbers. The front roll-centre is 2½ in. approximately above ground level. Independent rear suspension is achieved by a single trailing arm carrying the hub on twin dual-purpose bearings. The rubber suspension unit is mounted horizontally and again dampers are incorporated; the roll centre is at ground level, and each unit weighs 21½ lb.

Rack-and-pinion steering is used, the two-spoke steering wheel asking 2¹/₃  turns from lock-to-lock. The turning circle is 29 ft. 6 in. The brakes are 7 in. Lockheed cast-iron drum type, giving a lining area of 67½ sq. in. and incorporating the Lockheed pressure-reducing valve for the rear brakes. The hand brake is placed centrally between the seats. The pressed-steel 10 in. by 3.5 in. disc wheel carry Dunlop “Gold Seal” tubeless 5.20 by 10 tyres, giving 1,073 revolutions per mile.

The electrical system uses a Lucas C40 dynamo, and Lucas GLTW7A 12-volt 34 amp. hr. battery under the boot floor. Lucas F.700 headlamps, incorporating parking lamps, are used; there are direction-flashers with stop and tail lights in unit with them, two 35 amp. fuses protecting the circuits.

The two-door body is of spot-welded construction with a torsional stiffness of 6,500 lb./deg. over the wheelbase, the bare hull weighing 310 lb. The doors trail and have sliding windows and rope-type interior releases. Bucket front seats are fitted, the driver’s adjusting. A full width parcels’ shelf forms the facia, with central speedometer incorporating mileometer and fuel gauge, and warning lights. Enormous rigid pockets are found, not only in the doors but on each side of the back seat, while there is the usual shelf behind the back seat. The boot, with rather a heavy lid, holds 5½ cu. ft. of luggage and its lid folds down to carry further luggage, when the number plate hangs vertically from the lid to maintain legality — another ingenious detail! Normal models have cloth upholstery.

De-luxe versions of the Austin Se7en and Morris Mini-Minor have two-colour leathercloth upholstery and foam-rubber seat cushions, Screen washer, pile carpet, adjustable front passenger’s seat, hinged ¼-lights, wheel embellishers, sill finishers, better interior finish, passenger’s sun vizor, etc. As optional extras, heater, Smith’s radio, underseat stowage baskets and fitted suitcases are available. No Starting handle is supplied. The ADO.15s wheelbase measures 6 ft. 8 in., front track 3 ft. 11 ¾ in., rear track, 3 ft. 9 ⅞ in. They are 10 ft. long, 4 ft. 7 in. wide and 4 ft. 5 in. high unladen.

The ADO.15 is geared at 14.85 m.p.h. per 1,000 r.p.m. in top gear and at 5,500 r.p.m. the speeds in the gears are, respectively, 22½, 38, 58 and 81.7 m.p.h.

The Price

The price is so sensational it deserves its own heading! The basic price is £350, which purchase tax inflates to £496 19s. 2d. Even with many items of de luxe equipment the total price is but £537. If price were the only merit, which in the case of these cars it most emphatically is not, they could not help but be amongst the world’s best sellers. As it is, they appear to lead the world in small car design. — W.B.