THE 241ITRE LEA-FRANCIS /5.7 H.P. 6-CYLINDER FOR HIGH-SPEED TOURING
AS might be expected from a firm which has taken such ail active part in. racing and competition work in recent years, the latest sixcylinder Lea-Francis possesses many features which differ somewhat from the conventional, and which have been developed as a result of their extensive experience with their well-known supercharged 1500 c.c. car.
Realising the great demand which exists for a car which combines the performance of a good sports model with real sweetness of running, the firm have for over a year been experimenting with the model which is now known as the “Ace of Spades.” The name came to it in consequence of the shape of the front of the timing case, which is exactly the shape of that emblem, only inverted.
When we recently had an opportunity of trying for ourselves the performance and behaviour of this model, we were able to appreciate how remarkably well the designer has succeeded in his object, and were glad of the chance of examining some of the components.
One thing which has a great deal to do with the smooth running and high revving capabilities of this engine is the very robust crankshaft. This is carried in four bearings and is both statically and dynamically balanced, and fitted with counterweights. The journals are nearly as large as the cylinder bores, and besides ensuring abnormal rigidity, should give almost complete freedom from wear. Another good point is the freedom from oil-pipes to the various parts requiring pressure lubrication, all possible oil leads being arranged integral with the casting. Although the car we tried, the fabric saloon, was extremely roomy and comfortable, the performance was in no way impaired, and on quite a short stretch of road we attained 75 m.p.h. and there is no doubt that,
given more room, a higher speed could have been reached. There was a very slight period at 55 m.p.h. but this covered only about one mile an hour and throughout the rest of the range there was no sign of any vibration.
The actual engine we were driving was an experimental job, and differed in one or two minor points from the latest edition, and we are informed that this period has been entirely eliminated in the final design.
The gearbox is a very definite departure from standard practice, and is quite the most ingenious feature of a very interesting car. The casing is made in two halves, each housing two of the forward speeds, reverse being in the same compartment as first and second. These latter are of the normal sliding type, but the other two gears, third and top, are both engaged by means of dogs. The division between the two halves of the box forms a very stiff web which supports central bearings for the main shaft and lay shaft so that each shaft is supported on three bearings. The effective length of any loaded portion of shaft is thus reduced to the absolute minimum. It is a well known fact that a great deal of noise in gear boxes is due to the flexing of the shafts under load, and if they are not rigid even the most accurately ground gears will not be silent. In the new Lea-Francis’ box the loaded length of each shaft is not only much shorter than on any normal design, but additional rigidity is ensured by the fact that the unloaded half of each shaft has its end supported in a third bearing. It is a mechanical fact that a continuous shaft supported at intervals along its length has a smaller deflection for a given load on any one span than a single short shaft of the same length as that span. To test the effect of this design in reducing gear noise the car which we tested had been fitted with gears which had not been ground after hardening, and only a faint hum was audible, and it was much quieter than most boxes with ground gears. As the standard
job is fitted with ground gears, the new model should have one of the quietest gearboxes obtainable on any priced car today.
The steering has all those qualities of accuracy and easy control which can only be fully developed by actual road-racing experience, and the brakes owe their power and smoothness to the same source. These are di
rectly operated without servo assistance, the designers maintaining, in common with many great authorities, that on a light car this is the most efficient and positive method, providing the operating mechanism i s correctly designed. On many cars where drivers complain of the force required to operate the brakes, the trouble is due to lack of rigidity of the rods and cross shafts, resulting in the shafts binding in their bearings, and the power does not get as far as the brakes themselves. Judging from the robust design of this gear on the 2-litre LeaFrancis there should be no trouble • from this source,
while in actual use we found the operation commendably light. All components and accessories have been selected entirely for their efficiency, regardless of price or any other property. A Stromberg carburettor of the latest down-draught pattern supplies the mixture, and in conjunction with the Scintilla magneto contributes largely
to the life and smooth running of the engine. Other components not actually made by LeaFrancis include Lucas lighting and starting, Goodrich tyres, a Gallay radiator, Hartford shock absorbers, Hardy transmission couplings, Triplex screen, and Rudge
Whitworth wire wheels. For anyone
requiring a high-speed comfortable vehicle, suitable for long-distance work in all weathers it would be difficult to spend R495 to better advantage than on the “Ace of Spades” Lea-Francis, at which price both panelled and fabric saloons are offered.