SPORTING CARS ON TEST

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SPORTING CARS ON TEST. THE A.C. SIX-CYLINDER MONTLHERY SPORTS.

By RICHARD TWELVETREES. WITH the remarkable achievements of the six

” cylinder A.C. on the Montlhery Track still fresh in the memory of our readers, a few observations on the performance of the standard Montlhery Sports model will doubtless prove of interest, though at this season of the year one has to forego the maximum speed tests, which can only be carried out satisfactorily on the Brooklands track.

Eighty-five m.p.h. Guaranteed.

The model under review is very interesting from the sporting point of view, as it is one of the cars for which the purchaser can obtain an 85 m.p.h. certificate before

with a little practice, I found it possible to take many corners by the aid of timely skids, though this is not to be recommended as a habit.

Bitter experience has caused me to look suspiciously on a sports car with a noisy exhaust, but for ordinary traffic driving the A.C. is absolutely blameless in this respect, having a really remarkable top gear performance and a smoothness of running that would be hard to beat. In my opinion, the second gear is far too noisy, partly due, however, to the amount of wear to which the car had been submitted and, partly, I suspect, to design. The criticisms I have to offer are recorded as they

taking delivery and, as I shall point out in these notes, the “flat out” speed is not gained at the sacrifice of other features which make up an ideal specification for a sports car. The actual example submitted for our test was the first of its series and having been used for demonstration purposes for a period of eleven months, had already put up a mileage of approximately 22,856 miles. At the time of the test the weather conditions were the reverse of ideal and, as the tyres were somewhat worn, the car exhibited some inclination to skid on the greasy surfaces in town. These minor skids were rather intriguing in a way, as they demonstrated the easy manner by which the steering and general balance of the chassis permitted accurate correction. In fact,

appeared to me, for having pointed out the exact conditions under which the test was made, I am going ahead with a clear conscience.

As far as one could see, there was nothing much wrong with the clutch, which took up the drive very sweetly until one had to make a quick change with the engine revving fast. Then there was a slight hesitation after the pedal was released, possibly due to want of adjustment, but whatever the reason the fault was there. The gear change is good, though, personally, I should prefer a shorter movement from second to top instead of having to pull the lever through a distance of ten inches. I was not able to commend the front wheel brakes, because they, too, were not particularly well adjusted,

but though I can give no figures as to the full retardation, they worked smoothly and without snatch.

With these preliminary observations, I proceeded through town and made for Dorking to try the A.C. car up the well-known Zig-Zag at Box Hill, which at this time of the year makes quite a good test for any car. The surface was if anything worse than usual and deep ruts cut up the road between the first and second hairpin bends. The first climb was made from a standing start at the main road, the timed portion extending to a point opposite the stone parapet on the summit. In spite of the stony surface the car attained a speed of over 40 miles per hour up to the first bend and the corner was rounded at a good speed on first gear, firSt gear being used until a speed of 30 was reached on the next sloping section. The second hairpin was approached at 40 on second and rounded on first, though, as a matter of fact, this drop down was not really necessary.

The car took the corner very well, the steering lock leaving plenty of room without endangering impact with the bank on the left hand side. The third hairpin was taken in a similar manner, and the total time occupied in climbing was 3 minutes 30 2-5 seconds. On the second try this was reduced to 3 minutes 28 seconds, which shows that the ratios selected for the three-speed gear box are about right.

Then followed some acceleration tests from which the results given below were obtained. On first gear, the car reached a speed of 40 m.p.h. in 14 seconds from a standing start. By going through the gears, 50 m.p.h. was attained in 15 seconds and in 18 3-5 seconds the speedometer went round to 65 m.p.h. whilst still accelerating. Owing to the condition of the road it was impossible to go much faster, but I should say the maximum road speed was a little over 75 m.p.h. A little later Pebblecombe was climbed at 30 m.p.h., finishing up on first gear, with the engine turning over happily at a very high number of revolutions per minute.

Excellent Performance on Leith Hill. Running out to Leith Hill, I was a little doubtful whether the car would surmount the formidable lane

favoured by daring motor cyclists as an acid test, thinking this would prove a little too severe for a car with a high maximum speed, but the result showed that my fears were groundless, for the A.C. slithered through the slosh at the bottom and, warming up to its work as the more stony part of the lane was reached, trickled over the top with some power to spare.

The accompanying photograph gives an accurate idea of the gradient, the picture not being faked in any way, as may be seen from the level ground bearing away to the right.

The climb of this hill was really quite impressive and followed as it was by a trip across the heath towards Coldharbour, proved that the speedy little car was capable of acquitting itself with honours over an extremely rough” colonial section,” a fact which caused me not a little degree of surprise.

Another point that should be mentioned is the marked efficiency of the suspension system, which may be said to have had a thoroughly good test during the trip from the top of Leith Hill to Coldharbour. Though the ruts in places were so deep that once I got out to see whether there was enough clearance for the bottom of the crankcase, the riding was extraordinarily smooth and almost made one forget the nature of the ground being traversed. Not only did the suspension give practical immunity from road shocks, but also carried the chassis in such a way that the bodywork showed no signs of stressing, even on the roughest surfaces, and during the whole test I did not detect a single squeak or jar, though the car might have well been excused had it offered protests of this nature.

Good Touring Qualities.

Having completed the circus part of the performance I gave myself a treat in the shape of a long run on good main roads and then found the A.C. to run with great docility, the ease of travel being quite unusual in a machine capable of high speeds. The six-cylinder engine certainly gives a very remarkable degree of flexibility, and one can drive on top gear over all ordinary main roads without the slightest trouble; though perhaps this quality tends to encourage what

I may term ” lazy” methods of driving. The designers of the car have evidently succeeded in their aims to produce a fast car with a comprehensive top gear performance, and those who like this method of driving will certainly find their ideal in the six-cylinder A.C.

The Marks steering is light and accurate, the controls are all located in very convenient positions, whilst one can drive for hours on end without experiencing the slightest fatigue.

Technical Details.

As the A.C. chassis possesses certain features not commonly found in other makes, I will conclude my brief review with a few technical details. The car has a very good power to weight ratio, the total weight of the chassis being only a little over 9 cwt., though the

need adjustment are arranged with due consideration for the owner-driver.

As the car is intended to be driven mostly on top gear, a very large diameter single plate clutch is provided, having ample means for adjustment and presenting exceptionally generous wearing surfaces. Considerable care has been devoted to the design and construction of the rear axle, which, combined with the change speed gear and torque tube, forms a single unit. Three forward speeds are provided, together with a worm final drive and differential gear, the disposition of the mechanism in this way tending to increase wheel adhesion when steep and slippery slopes are tackled. The ratios of the gears are as follows :—first gear, 11.7 to 1; second gear, 6.3 to I; top gear, 4 to I; and reverse 15 to I.

engine is capable of developing 66 h.p. Unlike many sports cars, the mechanism has been designed with the definite object of providing continued reliability and there seems to be very little likely to get out of order, whilst the whole lubrication system is practically automatic, only three greasers being found on the chassis.

A particularly neat lay-out characterises the engine, of which the detachable head and valve gear can be removed without interfering with the valve timing or operating mechanism, and a special method of keeping the camshaft chain in correct tension is another good point in the design of the power unit. The clean lay-out of the engine has not been gained at the sacrifice of accessibility and all parts likely to

The Montlhery model A.C. provides another example of the beneficial influence of racing on standard design, and though the makers do not appear to have gone to any extreme limits, the A.C. undoubtedly represents a high ideal of light car engineering in which the demands of the sporting driver and the requirements of the long-distance tourer have been skilfully combined without over emphasising any of the respective characteristics.

The Court Treatt expedition, which arrived at Cairo recently after covering 14,732 miles in 16 months, used Wakefield Castro’ throughout their pioneer motor car journey from end to end of Africa.