Martin International has a 1496-cc (69 x 99 mm) OHC four-cylinder
engine, developing 56 bhp at 4500 rpm and rated at 11.9 HP.
Transmission comprises four-speed gearbox and worm-drive rear
DURING the last year or so Aston Martin cars have been developing from one general purpose sports model into two categories, the sports tourer and the semi-racing two seater. The 1932 programme therefore comprises two models, the International four seater, and the Le Mans two-seater. Both models use the same engine and chassis but the two-seater has a higher compression ratio and a close-ratio gear-box, and except for a slightly wider body is identical with the cars which were so successful this year at Le Mans. Having these two models at their disposal, the makers have concentrated on making one car definitely a tourer with sporting characteristics, while the Le Mans model is able to have a racing performance without worrying too much about slow running or the other refinements which one expects in a car intended for every-day use in town and country.
Motor Sport, August 1932
THE Aston Martin has always been built as a hand made sports car, nothing being sacrificed to considerations of price or production. Consequently it was expensive, and it is very welcome news to know that without losing any of the good qualities of the earlier model, the latest cars are announced at a substantially reduced price.
The chassis of the new model has undergone slight modifications. Looked at from above, from the front dumb-irons the chassis members sweep in below the radiator, widen out until they reach a point behind the gearbox and converge again towards the rear. The frame should be very rigid as it is braced at six points, tubular cross members connecting the side frames at the extreme front and rear of the chassis and also at the point where the headlamp supports and front shock absorbers are fixed, and in front of the rear-mounted petrol tank. Two steel pressings brace the centre part of the chassis.
From the side it follows the lines of the earlier model, being swept over the front axle and passing under the rear axle. The side members are 6 inches deep in the centre of the chassis.
The general design of the engine is unaltered, four cylinders 69 by 99 giving a capacity of 1,493 c.c. The nitralloy cylinder block and the crankcase are cast in one and the detachable head fitted with two overhead valves per cylinder carries an overhead camshaft in three bearings. The camshaft is driven by chain from the front of the engine and is tensioned by a spring blade, and a forked bracket keeps the sprocket in mesh when the head is removed for decarbonising. Valve clearance is adjusted by rotating the eccentrically mounted rocker pins. The sparking plugs are mounted on the inlet side of the head and a narrowing of the gas space on this side materially improves combustion. The pistons are of aluminium alloy and the duralumin connecting rods are bushed with white metal.
The Aston Martin lubricating system has always been of advanced design, as befits an engine which is built to run for long periods on full throttle. The oil is carried in a 2½ gallon tank between the front dumb irons and is pumped from there to a pressure filter which runs the whole length of the off-side of the engine. It passes from there through passages to the three main bearings and thence through the crankshaft to the big end journals. Other passages feed th: camshaft bearings, surplus oil returning to the sump down the timing chain tunnel at the front end.
An aluminium sump is fitted and is ribbed to assist cooling. A scavenger pump returns the oil at the opposite side to the intake in the dumb-iron tank, and this being fully exposed to the air completes the cooling process. An additional pipe from the tank to the sump releases the surplus pressure built up by the scavenger pump.
The filter can be detached by removing its aluminium cover, the two pumps are mounted externally at the front of the engine and the adjustable pressure release valve is accessibly mounted at the front end of the filter.
Two S.U. carburettors fitted with top feed float chambers are mounted on the off side, petrol being supplied by a Petrolift mounted on the dash. The exhaust manifold is on the near side of the engine, the exhaust pipe being carried down well clear of the dash. The magneto and the water pump are now carried on a spigot mounting at the front end of the engine, while the dynamo is coupled direct to the crankshaft.
An entirely new gear-box is fitted, second and third gear being silent and engaged by dog clutches. The ratios are :–4.66, 6.43, 10.48 and 16.31 to 1. The gearbox is spigot mounted on the engine, the flywheel housing and case being of aluminium. The drive is transmitted through a single plate dry disc clutch. The remote control gear-lever has been retained. An oil filter plug above the floorboards lessens the work of the owner-driver, and the speedometer drive is taken from the rear of the box.
The engine and gear-box unit is mounted on four bearers of circular section, two being bolted on to the crankcase near the front end, the other pair being similarly secured to the flywheel housing.
On the new models torque tube construction has given place to open propellor shaft drive, the shaft having at each end an exceptionally neat universal joint. Another alteration is the substitution of a bevel back axle for the worm drive previously used. The back axle is of normal banjo construction, which permits the interior to be examined without the whole assembly having to be taken down.
The 12 volt battery is divided into two units, one each side of the propellor shaft. Behind the back axle is a 10 gallon petrol tank, and with a petrol consumption of about 30 m.p.g. the car will have a fine cruising range. The spare wheel is fitted in a vertical position at the back of the body, its weight being taken by two troughs mounted on the rear dumb iron stay.
The front axle remains unaltered, the I section between the front springs giving place to a hollow circular section in the upswept parts which are subject to brake and steering reactions. The springs now take the braking reaction, the torque resisting cables not being required. Two rebound leaves are fitted, and additional slips stiffen the assembly. The second leaf is wrapped round the top one to guard against the consequences of a broken leaf.
The excellent 14 inch brakes have been retained, and the use of harder liners permits brake lining having a higher coefficient of ignition to be used. Operation is now by enclosed cables. These and the cross shafts are lubricated from grouped nipples in the centre of the chassis. The hand brake lever is on the off side, but being of the pull-up type, does not prevent easy access to the seats.
Lucas electrical equipment is fitted, and the double filament headlamps are controlled by a finger-tip control. A spring-spoked steering wheel is fitted, and the column is adjustable for rake.
The appearance of the new car is little altered, but a higher radiator is fitted, giving it a bolder front. The extra width of the chassis and the open propellor shaft allows the same amount of room as in the previous model, and the ground clearance remains unaltered.
The price of the open four-seater car has been reduced from £598 to £475, a move which will be welcomed by everyone. Apart from the simplification affected by such items as the new frame, which is easier to machine and unit engine gear-box construction, this reduction is accounted for by reduced costs on a larger output of cars, and the number of orders already received for the new model is most encouraging.
Motor Sport, July 1932