Motoring in the 1930's Part 2a
s Part 2A. The Cars Almost all cars made in the thirties were constructed with a separate chassis to which a body was added. The chassis was basically strong and usually was capable of being driven without the body attached, the completed chassis was sometimes driven to the ‘body shop’ with the driver sitting on a box. In the assembled vehicle brake and clutch pedals were operated through holes in the floor. Body construction was often in the form of a metal skin, sometimes aluminium, over a wooden frame, on some models fabric was used as a covering in places. Whilst the chassis were strong their two dimensional nature made them weak in torsion and, although there was some improvement in torsional rigidity derived from the body, this was not great with wooden framed bodywork so that there was a tendency for the car to twist when subjected to road variations, this usually led to creaks and rattles. On many cars it was possible to raise one corner of the car whilst the remaining three wheels remained in touch with the ground. Cars with steel bodies were naturally stronger in torsion, but the chassis strength was sometimes reduced because of that. All steel monocoque cars, where the body and chassis are integrated into a single structure, first appeared at the end of the thirties. Car production was very labour intensive with very much more dependence on the skill of the workers than is the situation today, consistency of standards and quality was more difficult to maintain with the result that there were good and bad examples of the high production models. In those days there were Daimlers, Rolls Royce and Bentleys and with this type of car there was much tighter control over quality. Bentleys merged with Rolls Royce in the thirties but they were still resting on the laurels of their Le Mans successes in the days when they were an independent company headed by W.O.Bentley himself. Those magnificent old Bentleys were beautifully made, they were fast but they were heavy. Ettore Bugatti described them as the fastest lorries in the world, nevertheless they did beat the opposition at Le Mans on a number of occasions. In Europe there were outstanding sports/racing cars such as Ferraris, Bugattis, and Mercedes. In Britain there were expensive sports cars such as Lagondas, Railtons, Invictas, and Astons. All these rather exotic cars were made in relatively small numbers, often the bodies were made by separate coachbuilders, but they were not representative of the majority of cars on the roads. Cars were too expensive for the working man but some of the higher production models were now within reach of the junior professionals and small business men. The best selling cars were the Ford 8 and 10, the Austin 7 and 10, Morris 8 and 10, Vauxhall 10 and 14, Hillman Minx and Standard 8. (The numbers with the models were the value of the horse-power calculated by a formula given by the RAC, it bore little relationship to the power of the car being dependent solely upon the piston area, but it was the figure used to determine the road tax payable. (A situation that encouraged engine designers in the UK to use undesirably long stroke engines). More up-market were the larger Austins and Morrises, Ford V8, Flying Standards (12, 14, 16), Wolseley, Rover, Humber, Armstrong-Siddeley, Lanchester et al. For a more sporty performance in the medium price range there were the MG, Wolseley, Riley, Morgan, SS and others. (During the war SS had sinister connotations and the name Jaguar was adopted in the post war period).
With very few exceptions, notably the Citroen ‘Traction Avant’ and some BSA models with front wheel drive, cars had engine and gearbox in line driving the rear wheels by means of a ‘prop’ shaft. Cars at the bottom end of the market used side valve engines with no oil filter or air filter. Not all had electric starters but all had starting handles. Some of the smaller engines had only a two bearing crankshaft. Big end bearing failure was fairly common, as much due to the poor quality of the oil compared with modern oils as due to the design, although there were no thin wall bearings. The oil was not multi-grade and very thick when cold and slow to circulate, trying to race up the road after a cold start could often result in a nasty rattle from under the bonnet. Neither was the petrol as good as it is today, ‘pinking’ (a minor detonation) was frequently heard, the side valve combustion chamber exacerbated this problem, as did poor control over ignition timing. The combination of poor quality oils and petrols and absence of filters led to the need for frequent overhauls. ‘Decarbonising’ was a fairly regular requirement, this involved cleaning carbon and other deposits from the combustion chamber and reseating, or replacing the valves. Reboring of the cylinders often proved necessary, sometimes after as little as 30,000 miles. Bore wear could be such that smoke could be seen pouring from the crankcase breather when at full load.
Even when new the engines in the 8 and 10 hp cars gave barely enough power to propel the car when fully laden. The power output of the 1litre Morris 8 was 27hp when the car was new. The low engine power led to a requirement for relatively low gearing by today’s standards. The maximum speed of a 1939 Austin 8, for example, was 56mph, but it would not be comfortable at that speed, a comfortable cruising speed would be about 45mph. The Austin 10, Ford 10 and the others were not much faster, they were all unable to exceed 60mph by more than 1 or 2mph and could not be driven comfortably above 50mph. That was when they were new, once the exhaust valves started to deteriorate, which they did fairly quickly, and the bores started to wear, the performance would fall off. A moderately steep hill might then require second gear, or even first. Then it was time for a ‘decoke’. That time might occur after as little as 20,000 miles. These engines were not designed for sustained operation at high rotational speeds. When the first motorway was opened in the 1950s many of these cars of pre-war design were still in use and they were driven as fast as they would go, even on the downhill stretches. Their little engines were revving so much faster than the designer intended and suffered a number of problems as a result. One visible consequence was the way in which the road became littered with broken fan belts.
Most popular cars had fixed ignition timing although control of ignition timing was sometimes left to the driver who had a lever on the steering column. Few drivers were able to use this control to achieve the best results. Most were aware of the need to advance the ignition as the engine speed increased but few appreciated the need to retard the ignition as the throttle opened and advance the ignition as the throttle was closed. For those who did have a good understanding it remained impractical to make the continuous adjustments necessary to obtain the best results. Automatic advance with increasing speed was introduced on some cars but few, if any, had adjustment linked to inlet manifold pressure. The ignition control lever on the steering column was often matched by a similar lever to give hand control of the throttle, supplementing the accelerator pedal which, incidentally, was sometimes to the left of the brake pedal. The hand throttle was particularly useful when starting by means of the starting handle. Starting was more of an art than a science. A choke was provided as a means of richening the mixture for a cold start, this was necessary in order to ensure that there was enough petrol in the air/fuel mixture to ensure an adequate amount in vapour form. Too much petrol and the air/vapour ratio could become too rich to ignite, furthermore the spark plugs could become wet with petrol, reducing the chance of a good spark. Most drivers got to know their cars and knew when to stop using the choke and whether or not to let more air in by opening the throttle. Even so, starting could be quite difficult on cold damp mornings, especially if the ignition equipment was not properly maintained. Some cars were worse than others, the side-valve Fords probably the worst.
Few popular cars incorporated a water pump in their cooling system, most depended upon a simple thermo-siphon process. This was usually adequate if the system was well maintained. Anti-freeze may have been available but it was not widely used. If a frost was anticipated the cooling water was drained and replaced the following morning, often with hot water to facilitate starting, using boiling water risked cracking the cast-iron cylinder head.. The consequence of frequent changes of water and not using antifreeze with corrosion inhibitors was corrosion and the formation of scale. The rust and scale would accumulate in the system and impair the flow through the radiator. To see a vehicle boiling was not at all unusual. Many cars did not have a thermostat in the system and those that did often had it removed in an attempt to improve the coolant flow. In cold weather the low rate of coolant flow, especially when a thermostat was fitted, could result in the water in the radiator freezing, stopping the flow and causing the water in the engine to boil. Radiator muffs that covered part of the front of the radiator were often seen, some were in the form of a roller blind that could be controlled by the driver, more often it was just a piece of card. Ron Watts