The Diatto has the considerable distinction of having been the fore-runner of the Maserati. Yet the first such cars were quite humble and rather ugly light cars, which were turned out by the engineering company of that name in Torino when it was not engaged in constructing railways. To this end Adolphe Clement was induced to join the Board and his Clément-Bayard cars were made under licence. It commenced in 1906, with unambitious T-head productions, but more interesting large Diattos followed, like the 28/38 and the somewhat smaller six-cylinder chassis.
This could be said to have been the writing on the wall, because after Clément had left in 1909 somewhat more modern engines replaced these T-head power-units. Moreover, Diatto had absorbed the Scarchi and Newton companies and when Italy entered the war they were put onto building military trucks and the straight-eight 250hp Bugatti aero-engine, although I believe the latter was never used in combat. After hostilities were over the link with Ettore Bugatti became obvious, when Diatto showed a 16-valve Diatto-Bugatti with an overweight closed body at the 1919 Paris Salon. That was a passing fancy however, and the Company nursed ambitions to go for mass production of good quality cars, until it was ousted from this fantasy by the great Fiat empire. To that ambition had been steered its Diatto one-litre small car and a continuation of the high-grade 2.7-litre four-cylinder model.
Not much was known in England about the make before and immediately after the Armistice of 1918, although in 1910 a couple of 15.9hp Diattos were raced at Brooklands. Indeed, it seems that another little-known Italian car, the Aurea (which, as I am bad at spelling, always reminds me of beef-suet), also from Turin, received better publicity here. This changed when Diatto introduced the 2- litre single-overhead-camshaft model in 1922, its design attributed to Guiseppe Coda, who had been responsible before the war for the Targa Florio SCATs. In accordance with its maker’s policy of using type-nurnbers this was known as the Tipo 20: the lighter car with its uninspiring appearance being the Tipo 10. It was this Tipo 20 and Tipo 20S that took the Diatto into the realm of effective sports cars. The Maserati brothers had been making Maserati sparking-plugs (now collector’s items) at Bologna and now Alfieri Maserati was hired to develop the 2-litre Diatto. This he did effectively, raising its power from 40 to 70 bhp.
This led to Meregalli winning the Circuit of Garda in 1922, 1923 and 1924 and Alfieri himself winning his class in the GP de Monza in 1922, apart from which there were some hill-climb successes. Later there were other class victories in some lesser Italian races, with drivers Brilli-Peri, Schieppari, Ferretti, Stefanelli, Aimini and Barsanti driving the Diattos, and it is said that Count Conelli had used a Diatto-Bugatti to win the 1921 Circuit of Brescia race for Italian drivers.
Meanwhile, the Bryanston Garage in London tried to interest British buyers in the sound 2.7-litre side-valve four-cylinder Diatto in post-war form, but apparently without much success, for racing driver Giulio Foresti took over, along with his lsotta-Fraschini agency, trying to sell this chassis for £950, in that difficult year, 1920. Even the appearance of a Diatto in the Targa Florio race and Foresti preparing a rather oddly streamlined racing Diatto failed to arouse much interest.
This notwithstanding, a Bagshot firm was engaged in selling the revised 10 hp Diatto, which had a slightly enlarged engine and a cowled-in fan behind its decidedly undistinguished radiator. The best that was achieved appears to have been the performance of V Oliver in the Junior Car Club’s Fuel Consumption Trial, in which, with the little Diatto that had arrived from Italy only a few days beforehand and was untuned, he came second, having achieved 68mpg, beaten only by a friction-drive GWK which, fitted with a carburettor the owner had made on his 3 1/2in Drummond lathe, managed an astonishing 86.1mpg.
It was the intervention of enthusiast Cyril Durlacher, AMIAE, who took a small stand at the 1923 Olympia Show, on which he exhibited the new ohc 79.7 x 100 mm (1995 cc) four-cylinder Diatto, that ensured success. The camshaft was driven by a vertical shaft, from which skew gears drove a cross-shaft for the magneto and waterpump. The cylinder head was detachable and the valves were operated by rockers. Additional rockers and dummy valve springs damped out camshaft fluctuations and at a time when overhead-camshaft engines were suspect, that of the Diatto ran with commendable quietness. Four-wheel-brakes were available for an extra £50 on the £495 chassis price and a sporting four-seater on this 15/40 hp chassis cost £650, Rudge-Whitworth wire wheels another £20. The former ugly radiator had been replaced by a smart one, in the Italian style.
From this stemmed the 15/50 hp sports Diatto, retaining the extremely neat engine exterior, notable for its smoothly-finished castings, which had a shaft-drive fan incorporating a tyre-inflator. The bodywork was of good quality but the dashboard and other items showed the hand of an engineer. For this model the wheelbase had been reduced to 9 ft 10 in, from the extended 10 ft 6 in of the touring chassis on which this had been done to give less cramped seating. The 2-litre Diatto pulled a top gear as high as 4.16 to 1, in conjunction with 820 x 120 tyres. In spite of its neat aspect, the engine’s components were easily accessible and in touring form this was a 70 mph car. One snag had been the transmission brake housed in an extension of the four-speed gearbox, which became covered in oil, smoked and smelt, but this was deleted for 1924.
Durlacher appeared in competition events to help publicise the Diatto, which he sold from his premises in Upper St Martins Lane, WC, where he offered full guarantees on ex-demonstrator and low-mileage cars. His service was well spoken of by his customers, an essential factor in making a success of dealing in new cars. His best effort in the racing field was finishing seventh in the 1927 Essex MC’s Six Hour Sports Car Race at Brooklands, linking the name of Diatto with such illustrious sports cars as the 3-litre twin-cam Sunbeam, 3-litre Bentley, 12/50 Alvis and Salmson. Dudacher’s 2-litre Diatto won its class, partnered by F. Clifton, at 59.2 mph, beating AC, Lagonda and OM opposition.
The 15/60 hp Diatto of 1925, priced at £550 as a chassis, was an 80 mph super-sports car with good road holding, pleasant to drive, featuring a friction clutch in the cooling fan drive and a Faudi patent spring-damper in the steering drop-arm. The light steering, light clutch action and good castor-action were praised and the owner who complained of heavy steering admitted that the castor return was effective. English bodies, such as by Salmons, were put on the touring chassis but it is the fast versions that are best remembered.
At the 1924 Show Durlacher had shown a two-seater with English body in brilliant crimson, with mudguards in dark amaranth, and the following year a car finished in scratched aluminium with black flared wings, vee screen and red upholstery. The central gear and brake lever were both knobbed, the back springs were half-elliptics, replacing the cantilever rear springs of the touring chassis. Those who sought even more performance were offered a 20 hp 93 x 106mm (2952 cc) engine, on the Tipo 30 Diatto. Solex carburettors and Bosch electrics were used on both cars.
However, all good things come to an end; in Diatto’s case the Maserati brothers lost interest when the firm’s modest racing programme ended. Alfieri had designed and had built a very handsome 2-litre GP car in the supercharged straight-eight twin-cam tradition, which was driven in the 1925 Italian GP by Materassi. It was too new to succeed and retired with supercharger problems. But it pointed the way ahead and the Maseratis took it and its equipment over and the great Maserati racing concern was started at Bologna, the outcome of which was to make such an impact on the motor-racing world. By 1930 Durlacher had no new Diattos to sell. WB