Some alterations to a 1.5-Litre A.C.
The old gearbox-in-back-axle A.C., which recalls so vividly the great pioneer S. F. Edge, is a rare car now. But it was an attempt to offer a lightweight 1.5-litre, and the alterations carried out by Signalman D. Hings to one of these cars are consequently of more than passing interest.—Ed.
Some time ago an interesting car was sought to replace an Anzani Frazer-Nash, which, unfortunately, had to be disposed of some months before, because of the war. During a tour of some breakers’ yards, a 12-h.p. A.C. of 1927 vintage was discovered, possessing what appeared to be an Anzani engine, although “A.C.” was embossed on the cylinder head. Subsequent enquiries proved that it was made by Anzani, and is similar to those fitted to the early Frazer-Nashes. The car was of’ very light construction, with an aluminium 2-seater body, and, in fact, appeared to be almost entirely made of aluminium. The body was in quite good condition and even possessed a good hood, two undamaged side-screens, and a radiator muff. Needless to say, the former two items will not often be used! The car was shod with five quite reasonable tyres, and the only apparent mechanical faults were a split carburetter float and a leaky radiator. These defects were cured by somewhat crude plumbing, and the engine started easily, appearing quite healthy, with reasonable compression.
According to a road-test of an earlier model, top speed is only 50 m.p.h., but the very creditable petrol consumption of 35 m.p.g. was obtained. It was felt that considerably better performance could be expected, so the following modifications were carried out.
First, the minute Solex carburetter, befitting an Austin Seven or Fiat “Mouse”, was replaced by a 30-mm. S.U., this being the size of the inlet manifold, which, incidentally, is water-heated, as it passes through the block. For the fly-wheel the makers went to the other extreme, and fitted one eminently suitable for a steam-roller! This will have to be lightened considerably when peace returns and such jobs can be done without priority certificates, etc. Fortunately, a lot can be taken off without interfering with the clutch. To provide anchors on all four wheels, the front and rear axles of the 2-litre model were fitted without any great difficulty. these also giving a wider track and improved appearance, as they have Rudge wheels instead of the discs. The wheelbase is 8 ft. 9 in. and the track is now approximately 4ft. 2 in.
The chassis is of channel section and rounded at the front, following the shape of the radiator. A cross-member amidships supports the front end of the torque tube through a universal joint. Quarter-elliptic springs are used back and front, and it is extremely doubtful whether the front ones will behave themselves when subjected to any degree of braking, as nothing is provided to take the torque. However, the 2-litre car apparently behaved itself’ satisfactorily in spite of this, as they were quite popular; incidentally, the front brake drums were considerably smaller than the rear. The 1,496-c.c. side-valve Anzani engine develops 45 b.h.p. at 3.000 r.p.m., at which speed the piston velocity is still quite appreciably below 2,500 f.p.m. The weight of the engine is only 160 lb.. so it is a pretty efficient little s.v. unit, and, as John Bolster so aptly said in his, article “G.N. Gen” last November, it “gave more power than it had any right to do”. This urge is transmitted through a dry, single-plate clutch to the gearbox situated in the back axle casing. Incidentally, stronger clutch springs will be required to deal with the increased urge, for on the only test run possible, clutch slip was noticed when changing up.
The whole of the propeller-shaft tube and rear axle casing are of light alloy. The gear ratios are 5 to 1, 7.3 to 1 and 14 to 1. The gear lever is on the off side; surprisingly enough, very quick and easy changes can be made although no clutch stop is fitted. Possibly the friction in the universal joint and various bearings would account for this. The maximum engine speed gives 66 m.p.h. in top and 46 m.p.h. in second, but an alternative final drive of ratio 4 to 1 is available, this giving a (very) theoretical top-gear maximum of 82 m.p.h. with 55 m.p.h. in second. No doubt the car would be most unmanageable if this speed was attained, but the advantage of the higher ratio would be a comfortable cruising speed of 55-60 m.p.h., although bottom gear might prove to be too high. However, the car is little if any heavier than the ‘Nash, which had a bottom gear of about 10 to 1.
The steering is high-geared, requiring 1, 1/3 turns from lock to lock, but did not seem very accurate. Increasing, the castor angle would no doubt improve it, as would the fitting of shock absorbers all round. The driving position is set well back, and visibility is good, due to the low bonnet. The total weight is about 13 cwt., and this gives the weight/capacity ratio of’ 1 lb. per c.c., the same figure as that for a Triumph “Tiger 80”, a motor-cycle of no mean performance.
The test run mentioned took place along the North Circular Road with three up, and proved very enjoyable. The original silencer having almost completely rusted away, a motor-cycle Brooklands type silencer was temporarily affixed to comply with the law, and for this same reason a suction horn with a particularly unpleasant note was attached; judging by the looks of amazement on the faces of several “buzz box” drivers who were overtaken, our progress must have been truly inspiring. If in happier times to come you should meet YP 7469, a rather old and sedate-looking A.C., please do not be too rude!