Matters of Moment, May 1972
Independent, or not?
The heading applies, not to whether or not Britain should become a member of the EEC but to how long it will be before the live back axle, too lively on many cars, will become as much a museum-piece as the sprag and the low-tension (or for that matter high-tension) Magneto. Some years ago Motor Sport was a strong advocate of cars without propeller shafts and campaigned strongly for independent rear suspension. While our enthusiasm for front-wheel-drive for all cars may have been a bit misplaced, the fact remains that more and more small cars, from the irrepressible Issigonis Mini onwards, have resorted to FWD, after a troublesome period while universal couplings were being devised that would stand up to it. Today customers of BL, Auto Union, Citroën, Datsun, Fiat, Honda, Lancia, NSU, Peugeot, Renault, Saab, Simca, Triumph and Wartburg small and not so small cars have the benefits of being pulled along by the front wheels of their prop.-shaftless cars.
Less progress has been made towards the elimination of the cross-beam live end, and cart-type springs but i.r.s must surely, in the end, oust a system unsuited to the application of power to the road. It may go as front drive takes over, or when design teams take a universal plunge towards the elimination of the old-fashioned back axle. We used to ask Chief Engineers of the great motor manufacturers why they eschewed i.r.s. and were inevitably told that there was no need for it except on the most extreme examples (this with noses in the air, as if evading an unpleasant odour) of high-performance cars ; or, more honestly that it was too costly to contemplate. This seems a line of thought which continues to prevail among the Big Three, except that Ford of Britain eventually got rig of conventional back axles on their largest (Zephyr and Zodiac) models and, in spite of roads tending to become straighter and smoother surfaced, have revised i.r.s. technicalities on their new Consul and Granada cars (Consul GT illustrated above).
All credit to Ford for this advance: BL, Chrysler UK and Vauxhall complacently go on using back axles on their RWD cars, perhaps hoping that the straightening of main roads and the increased Motorway mileage may diminish the driving-time during which the full merits of i.r.s are experienced. This is a fallacy, because the upward trend in car performance makes it ever more necessary to ensure that the increased power can be put on the road without promoting wheelspin which can upset stability or hold back the available acceleration, apart from the gains in road holding and comfort which should be an added bonus for good i.r.s layout.
These are simple facts which racing brought into focus, causing i.r.s. to dominate the GP scene after 1935. Indeed, the last Grand Prix to be won by a car with a live back axle was the 1935 German GP, but it took the virtuosity of Nuvolari to achieve this, and the P3 Alfa Romeo he drove had that ingenious dual propeller-shaft transmission whereby the usual half-shafts were eliminated and the differential transferred to the chassis, the considerable reduction in unsprung weight this obtained contributing materially to better road-holding, in much the same way as the well-located, lightweight live axles of current production Alfa Romeos give such excellent results, albeit the P3’s clever back axle did not give the full benefits of i.r.s. as one eminent engineer/journalist mistakenly thought at the time.
With the advent of the very powerful Mercedes-Benz and Auto-Union GP cars i.r.s. became virtually essential and was used at first in swing-axle form, with torsion bars as a later refinement in the suspension damping department. This gave rise to unwanted oversteer, which both makes eradicated by resorting to de Dion rear axles. The low unsprung weight and lack of torque reaction between the drive unit and the axle which is the merit of i.r.s. was retained but the wheels lost their gyroscopic effect and could be located so as to promote understeer, which is also achieved by i.r.s. systems employing trailing arms and additional universal joints. It is significant that de Dion rear suspension has been used by Lancia and Maserati on production cars and is still favoured by Aston Martin, Iso, Monteverdi and Rover. (Incidentally, the Mercedes-Benz racing engineers soon eschewed sliding splines for the driving shafts in favour of de Dion-pattern universal joints, and in the modern Rovers a splined de Dion tube is used in conjunction with fixed-length-drive-shafts. Softer suspension and hydraulic dampers were another racing-car-fostered development at this time.)
Refraining from a long historical discourse about the evolution of i.r.s., and pausing only to pay homage to those pioneer layouts which come to mind, such as those of Rumpler in 1921, Mercedes-Benz in the early 1930s, W. O. Bentley’s Lagonda after the war, Triumph’s Herald in 1959 and Chevrolet’s Corvair in 1960 we can now list those enlightened manufacturers who use i.r.s. on current catalogue Panhard layout cars (ignoring FWD designs in which the need for i.r.s. is materially lessened and rear-engined vehicles which are virtually forced to adopt it), as AC, Bentley, BMW, Chevrolet Corvette, DAF, Daimler, Datsun 240Z, Fairthorpe, Ferrari, Fiat 130 and Dino, Ford Consul and Granada, 3-litre Ginetta, Jaguar, Lamborghini, Lotus Elan, Mercedes-Benz, NSU Ro80, Peugeot 504, Renault 16, Rolls-Royce, Triumph and TVR.
It seems high time for others to follow suit! Ford of Britain are to be congratulated on using improved i.r.s. on their competitively priced Consul and Granada. Someone who had just sampled the 3-litre V6 version of the latter remarked to us that its handling reminded him of a Mercedes-Benz, the improved sense of control and higher cornering power having been achieved without recourse to a harsh ride. It will be interesting to assess the situation five years hence, when we shall expect more manufacturers to have gone over not only to i.r.s. but to self-levelling suspension systems as provided by Citroën from 1948, Packard in 1955 and by Citroen, Rolls-Royce and Mercedes-Benz at the present state of play. As it is, much enlightenment has resulted since the last vintage year, when only 1.57% of cars on the British market had independent front suspension (today only the Range Rover employs a beam front axle) and leaf springs were almost universal. Forty years later a surprisingly large number of cars still resort to springing uncharged in principle since the era of donkey carts, but one must not be too critical, for even here advances have been made, in the use of single-leaf springs, etc., as no doubt Jonas Woodhead would be only too happy to point out. . . .
Ford’s splendid Safari
Congratulations to Ford on not only winning outright the E. African Safari (report, page 470, pictures centre-section) as well as taking the important Team Prize, with their Escorts—thereby stemming the Japanese invasion of this toughest of “customer-relations” international Rallies, but to Mikkola and Palm for at last breaking the legend that non-residents cannot win the Safari. (Even if they did have fan-belt anxieties, which in vintage times the more enlightened designers obviated by using positive drives for fan, water pump and dynamo—one such car was the 12/20 Calthorpe and no doubt some of our readers could add others.)
We have long regarded Ford as the leading supplier of practical transport for the masses since 1908, the year the immortal Model-T was introduced, and more recently Ford has added sound sporting saloons for those who favour cars with a bit of beef.
General Motors, whose cars seem to us stodgy in comparison with those of the scripted four-letter make, do not officially condone competition work but it is significant that their Opels, which are the exception to the foregoing premise, have been doing well in the important rallies. Moreover, if we were Lord Stokes we would want to pit our advanced-engineering conceptions, from Minis to transverse engined-sixes, against the all-conquering Fords.
Meanwhile, salutations to Ford of Britain, not only for coming out top in the Easter Safari which eliminated 67 of those who started, but for releasing immediately afterwards realistic advertisements advising customers that Escorts can be seen and tried at Ford Showrooms. The Safari victory may not be apprehended by many thousands of Escort owners but a great many of them must have felt a justifiable glow of pride when the results came through and, although the Escorts you can buy are not exactly patterns of the Safari Ford as driven by Mikkola and Palm, the Company’s engineering and organisation which enabled it to in the Safari must surely pay off in terms of good consumer relations.
Schrader’s energy saver
The other day I came upon the Continental Correspondent standing by a four-cylinder car the engine of which sounded as if it was idling on two cylinders. “No, on three”, he said, in reply to my look of alarm. It transpired that he was inflating the tyres of an older car from one of the cylinders of the engine I had heard, using a Scovil Schrader Spark Plug Air Pump.
There is nothing new in this, which is a simplification of those little inbuilt air-compressors incorporated in certain luxury cars such as the V8 De Dion Bouton, the big Packards, post-war 20 h.p. Wolseley, etc. I then remembered that last year we had been sent this Schrader Spark Plug Air Pump for test but I had discarded it as a gadget which would probably pump carbon and hot gases into the tyre it was blowing up. I should have known better of A. Schrader’s Son, who have made such excellent tyre valves and such sensible valve caps for so many years. It was pointed out to me that an ingenious ball valve is used, which passes only fresh air as the immobilised cylinder into which it is screwed by hand, in lieu of the sparking plug, converts it into a miniature air-pump. There is a tube long enough for a car to inflate its own tyres or those of another car beside it. This clever air-pump is also a splendid energy saver for inflating rubber boats, tents, etc. The Type 8888R comes without a pressure gauge, in a light blue wallet. Type 8888RG incorporates a gauge and is packed in a black wallet. The respective prices are £1.99 1/2 and £4.28, which is less expensive than buying a decent pump and a tyre gauge and much less exhausting to the user! The air-pump has three thread sizes, 18 mm., 14 mm. or compression-top diameter and it can be used for inflating liquid-filled tractor tyres providing the adapter is put on and taken off the tyre valve while the engine is running. The makers of this very worth-having accessory are A, Schrader’s Son, 829 Tyburn Road, Erdington, Birmingham B24 9NZ.