BMW 328

HJ Aldington in the BMW 328 at the Munich Triangular Race, 1936 — HJ Aldington of Frazer Nash in prototype BMW 328 85001 at the Munich Triangle Race, 1936, which he subsequently won.

In a 2001 article ‘The legendary roadster’ Geir Kvalsvik described the first BMW 328 in emphatic terms:

“In the 328 Roadster, BMW produced a car which became a legend of sports car and racing history. Like scarcely another sports car beside it, this compact two-seater with leather straps across the bonnet came to dominate the racing scene in Germany and around the world in the second half of the thirties. “
[Kvalsvik, 2001]

This is a view shared by members of BMW itself. In the preface to a book [Simons, 1996] on the pre-war 328, Bernd Pischetsrieder, the then Chairman of BMW AG, was similarly emphatic:

“The BMW 328 is more than just a legend of the past. It is the BMW legend. “
[Simons, 1996]

BMW’s Move Into Motorcars and Motor Racing

In the 1930s BMW became a leading force in motor racing and sports cars, seemingly from nowhere. BMW had started in 1917 as a manufacturer of aircraft engines (hence the propellor inspired logo) and had subsequently diversified into motorbikes. However, in 1929 BMW inherited both a motor car and motor racing tradition when it was asked to take over the financially troubled Gothaer Waggonfabrik in Eisenach, Thuringia (in central Germany).

The factory’s roots went back to 1898 when it used the Wartburg brand and from 1903 it also used the Dixi marque. The year the Eisenach operation became part of BMW, three Dixi 3/15 hp (themselves modelled on the Austin 7 Ulster) were renamed the BMW 3/15 Wartburg. The three cars took a clean sweep at the International Alpine Trial of 1929. This was the start of a BMW motor racing tradition that led directly to the BMW 328 and to a dominant position in BMW’s chosen pre-war sports car and small saloon niche. A division of labour quickly emerged between Bavaria and Thuringia, the technology development was carried out by the development team in Munich, and production took place in the experienced factory in Eisenach.

BMW and Motorcar Design

While Franz Joseph Popp, the managing director of BMW, was reputed never to drive himself, he built a talented team including two innovative engineers, Rudolph Schleicher and Fritz Fiedler. The two had both met at Horch (the predecessor of Autounion and Audi) in Zwickau, in south-west Saxony. When Schleicher moved from Horch back to BMW in 1932, he believed only Fiedler could build a chassis adequate for the six-cylinder engine he had developed, so Popp negotiated Fiedler’s move to Munich. Schleicher and Fielder produced innovations that proved central to the 328’s advanced engineering.

Engine Design

It was Schleicher who developed a six-cylinder engine design for BMW. The engine had both superior stiffness and lower production costs than the competing designs put forward by two of his BMW colleagues. The engine was first installed in the BMW 303 (using the car model designation familiar today) and then went into what was by modern standards, a rapid succession of new BMW models, leading to the 328 in 1936 [Simons, 1996].

For the 328 Schleicher wanted to develop his engine further but, as development money was tight, it had to be an adaptation of his existing one. The challenge they set themselves was to achieve a more optimal, hemispherical combustion chamber using inclined valves, yet without increasing the height of the engine with an overhead camshaft.

The solution came at the 1935 Automobile Salon in Paris, where Schleicher and Fiedler saw a French Talbot Lago T-150 that used British Talbot’s side valve design. This had been developed twelve years before by Talbot’s Swiss chief engineer, George Roesch. So a redesigned cylinder head was created to go on Schleicher’s existing cylinder block with a single, side-mounted camshaft. Unlike the Talbot design, which used long and consequently rather flexible pushrods, the design devised by Schleicher and his colleague Rudolf Fleming, used short push rods for the exhaust valves. This allowed short and therefore both light and rigid rocker arms. [Simons, 1996]

The design was described in Schleicher’s own words, in the application for registration as follows:

“Four-stroke engine, in particular which can be converted through exchanging the cylinder head of an engine with side valves into a high-performance, characterised by the combination of the following well-known features:
a ) overhead valve arrangement in the cylinder head, whereby the valves are at such an angle to each other that there is a nearly spheroid combustion chamber;
b ) valve activation of both rows of valves by the side-mounted camshaft and that of the valve row next to the camshaft by pushrods and rocker arms, and that of the other valve row via an additional, second rocker arm and an interposed pushrod, which then bridges the gap created by the valve angle.”
[quoted in Simons, 1996]

Chassis Design

Matching Schleicher’s engine development were Fiedler’s developments in chassis design. The team at BMW advocated the concept of ‘Leichtbau’ (light weight construction), again initially for the BMW 303. As BMW pointed out to their customers, the heavier a car, the greater the centrifugal force tearing it away when cornering. In addition there were all the advantages of an improved power-to-weight ratio. So, rather than a rectangular chassis made of heavy steel channel, which had been typical of cars since the start of the century, Fritz Fiedler developed a different approach. He patented a lightweight tubular A frame that tapered towards the rear, with rectangular, tubular cross members. It was transformational as it combined higher bending and torsional stiffness, with reduced weight. [Simons, 1996]

Other Innovations in the BMW 328

Alongside these innovations were other developments in the design of the 328. Rather than use the Rudge-Whitworth central locking patent, the wheels had discs and the Kronprinz quick-release attachment method, using four pins to centre the wheel. Rudolf Fleming patented an oil cooler in front of the water radiator, to which lubricant was only supplied after achieving its operating temperature.

To comply with international sports car regulations of the time, the 328 has two brown leather bonnet straps and the characteristic double kidney grill of BMWs. Aesthetics were very much at the forefront of the design philosophy at BMW, with the beautiful bodywork for the 328 designed by Fiedler, Peter Szymanowski and Kurt Joachim, and with Dr Hermann Beissbarth in charge of aerodynamics [Simons 1996]. Production models also had fitted doors, a glove compartment with a lid, twin Bosch horns and a toolkit under the bonnet.

In short, in the 328 the BMW team produced a car that was light and fast, deeply attractive, very comfortable to drive, with engineering well ahead of its time.

Launch

By the time the BMW 328 was ready in April 1936, the project had taken barely a year [Simons, 1996]. It was quietly but rather effectively launched on 13th June 1936 by competing and winning in the Eifel Trophy Race on the Nürburgring. It received headline coverage when the motorcycle speed record holder Ernst Henne won by an impressive two minutes and 27 seconds ahead of the nearest competitor.

Production

Production models became available in BMW dealerships from the end of February 1937.

Including the three prototypes, the total number of 328s, built at Eisenach was 464. There were 48 fitted with right-hand drive at the factory, all going to Great Britain with the exception of one to Columbo (in Ceylon) and one to Melbourne, Australia. [Simons, 1996]

The chassis numbers started at 85001 (the intial three were the prototypes). The first series of 328s were chassis numbers up to 85279. They were assigned 328/0 (for left-hand drive) and 328/1 (for right-hand drive). The second series had an improved Hurth gearbox (with synchronisation in third and fourth gear) that was more capable of handling the increased torque of the 328. It also had a heavier rear axle and an optional sports camshaft (with increased valve lift). There were also minor changes to the dashboard, protection of the rear wheel arches and reshaped seat backs. The second series started from chassis number 85280. They were designated 328/2 (for left-hand drive) and 328/3 (for right-hand drive). [Simons, 1996]

Race Success

Throughout 1936 and 1937 the BMW 328 scored multiple victories in Germany, the UK, Finland and Romania. A dedicated BMW race support team assisted the growing number of privateer entrants into races. In the 2 litre sports-car class BMW 328s then dominated across Europe, for example winning its class in the Mille Miglia, until 1940, when racing stopped because of the war (see also Frazer Nash & BMW).