Motoring in the 1930s
Ron provides a professional overview of the 1930 automobile
Part 2 Cars
Practically 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. All steel bodies did appear on some high production cars but they were still fitted to a separate chassis. Whilst the chassis were strong they did usually gain extra strength from the body. Nevertheless the two dimensional nature of the chassis made it weak in torsion and, despite the extra torsional rigidity derived from the body there was a tendency for the car to twist when subjected to road variations, this usually led to creaks and rattles. On most cars it was possible to raise one corner of the car whilst the remaining three wheels remained very firmly planted on the ground. With very few exceptions, notably the Citroen 'Traction Avant' and some BSA models, cars had engine and gearbox in line driving the rear wheels by means of a 'prop' shaft.
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. Enzio Ferrari described them as the fastest lorries in the world. 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 to use undesirably long long stroke engines). More up-market were the larger Austins, Ford V8, Flying Standards (12, 14, 16), Wolseley, Rover, Humber Armstrong-Siddeley, Lanchester et al. For a more sporty performance there were the MG, Wolseley, Riley, Morgan, SS and others.
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 was very thick when cold, 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' 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.
Even when new the engines in the 8 and 10 hp cars gave barely enough power to propel the car when fully laden. 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 about 30,000 miles or less. 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.
Some cars had fixed ignition timing but control of ignition timing was often 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 advance the ignition as the throttle was closed and retard the ignition as the throttle opened. 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.
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. The consequence of frequent changes of water and not using antifreeze with corrosion inhibitors was corrosion with a build up of rust 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 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.
Gearboxes were usually three speed, although some were four speed especially on the more up-market cars. In the early thirties many had plain gears with no synchromesh, these required the driver to synchronise the appropriate engine speed with the road speed in order to get a smooth change and that involved using the clutch twice on each change, or 'double declutching'. This procedure required a certain level of skill that not all drivers acquired. The noise of gear changes could sometimes make you wince as you heard the grinding of metal, not surprisingly this type of gearbox had the name 'crash box'. Synchromesh was widely adopted during the thirties but it was mostly limited to the top two gears. Some of the more expensive cars had a free-wheel, Rover and Triumph for example, the free-wheel could be engaged or disengaged at will. The free-wheel offered opportunity for some fuel saving whilst free wheeling, and the ability to select a different gear in advance of requirement. With synchromesh these gear changes could be clutchless. Many drivers were not too keen on the free wheel because of the consequential loss of engine braking. Epicyclic gears were used in some cars, most famously in the Model T Ford of course, their use in the thirties was generally associated with a fluid flywheel in place of the clutch, notably in Daimler and Lanchester cars. They were generally associated with a pre-selective gearbox which enabled the driver to select his next gear before actually engaging that gear by operating a pedal. This type of arrangement was widely adopted for buses and was the fore-runner of the automatic box.
Rigid axles mounted on leaf springs of the semi-elliptic or quarter elliptic type were almost universal on British cars. These 'cart springs' offered a cheap and simple, if not very precise, means of locating the axles but they were far from ideal. They are still widely used on commercial vehicles where their shortcomings are of less concern. The rigid axles increased the potential for a pitching motion and their weight contributed more to the unsprung weight, with detrimental effects on the ride quality. Many cars used friction dampers in association with leaf springs. Whilst these crude suspensions were very inferior to those of modern independently sprung cars their shortcomings were less apparent because of the lower speeds in use.
Steering was usually through a steering box. 'Worm and peg' and 'recirculating ball' were the most favoured mechanisms. All steering boxes were less precise than the modern rack and pinion method, they also tended to wear, leading to increasing amounts of play. When driving it was usually necessary to make constant minor adjustments to the direction of the vehicle because of this play in the system. The effect of steering and suspension geometry on the handling of the vehicle was less well understood also, making for more difficulty in maintaining the desired course. Swivel pins (or king pins) were supported in plain bushes that were exposed to the elements. Nearly all steering and suspension moving joints required very regular greasing. This was very demanding and often not done as frequently as it should have been with the result that water and dirt would get to the bearing surfaces leading to rapid wear and excessive play. This all went to make the car less pleasant to drive, more noisy, more difficult to control and potentially more dangerous.
Most British manufacturers tended to favour 12volt electrical systems, although some used 6volt. The Americans favoured 6volt, despite the heavy starting demands of their large engines, and they adopted the same policy for Fords in the UK. The starter current on a 6volt system could be as high as 100amps or more, twice as much as that for a 12volt system. Coil ignition with the contact breakers integral in the distributor had become established as the preferred method and was almost universal by the late thirties, this method persisted through to the 1970s. It was reliable but did require regular maintenance, badly adjusted or dirty contact breakers were the most common cause of difficult engine starting. The sound of a starter grinding away until the battery was exhausted was common place. Dynamos rather than alternators were used to charge the batteries. Dynamos necessitated an automatic cut-out to prevent the reversal of current from the battery to the dynamo together with a voltage regulator to limit the charging volltage. These units tended to break down occasionally. It is more difficult to manufacture dynamos to withstand high rotational speeds, the centrifugal forces can cause the commutator to disintegrate. In order to avoid excessive dynamo speeds at high engine speeds the belt drives were chosen such that at low engine speed the electrical output from the dynamo was also low. This was a potential problem when driving in heavy traffic at times because the battery could be run down when there was a requirement for lights and perhaps windscreen wipers. The introduction of additional equipment such as radios (and heaters and de-misters on post-war cars) exacerbated the problem. (it was not until further advances in electrical engineering that the mechanically robust alternators were able to be used). Car radios did appear in the 1930s, they used thermionic valves of course and were heavy and made heavy demands on the battery.
Insulation on the wires was mostly rubber, not plastic, the rubber tended to deteriorate with age, especially when situated in a hot region under the bonnet. The combination of crumbling insulation and high electrical currents, especially with 6volt batteries, presented a greater fire risk and car fires were more common despite the protection provided by fuses. Overall electrical systems were very very much simpler than on a modern car. On most cars there was only a requirement for lights, a horn and an ignition system, with the associated battery and charging equipment. Some cars had indicators in the form of 'trafficators', these were electrically operated mechanical arms that were raised on either side of the car, the arm containing a bulb for night time visibility. They were pathetic in comparison with modern flashing indicators, they were notoriously unreliable and, when they did work, they were easily missed by other drivers.