BMW 303 Cabriolet ( 1934)
The BMW 303 was a small car that was built by BMW in Eisenach 1933-1934. It was the first BMW inline six- cylinder engine and the radiator grille, kidney-shaped, which should be so typical of BMW.
1931 BMW decided in accordance with a cooperation agreement with Daimler -Benz, a new car above the successful BMW 3/ 20, with up to 1.3 liter displacement and six-cylinder engine to develop.
Max Friz designed in Munich a very modern engine with an aluminum crankcase and overhead valves in the removable cylinder head; his former colleague Martin Duckstein designed in Eisenach, however, a very simple motor with cast iron cylinder block, side valves, only three bearing crankshaft and cast iron cylinder heads.
General Popp commissioned in the summer of 1932 the experimenter Rudolf Schleicher with the assessment of the competing engine designs. Then put Schleicher and his colleague Karl computing its own draft: an inexpensive cast-iron engine block, but with four instead of three crankshaft bearings. The cast-iron cylinder head had overhead valves and was powered by two updraft carburetors with mixture. Schleicher and computing led this one the proven and successful modular concept of BMW motorcycles with numerous common parts, sustainable development opportunities and use of existing machines in the car - building at BMW. Also American design principles of large-scale construction served as a model - after all, made BMW since 1928 the aircraft engine Pratt & Whitney R- 1690 Hornet Hornet as BMW under license.
Hans Nibel, chief engineer at Daimler -Benz and a good friend of Franz Josef Popp, was finally consulted and decided right away for the design of Schleicher and computing, which was then implemented.
The chief engineer Fritz Fiedler, who joined Horch in Zwickau on BMW in August 1932 took place in Eisenach a new framework of U- profiles for the 303, but does not satisfy his requirements. He designed in a short time a lightweight frame made of round longitudinal pipes and box-shaped cross members. Also the chassis was redesigned so that the trend for the following years.
BMW introduced the Type 303 before at the 24th International Motor Show in Berlin in February 1933.
From Ambi- Budd optional three bodies were offered: a 2 -door sedan with 4 seats (RM 3600 -), a 2-door convertible with 4 seats (RM 4400, -) and a 2-door sports convertible with 2 seats (RM 4600, - ).
1934 sparked the larger BMW 315 type 303 from 2300 copies.
The vehicles of an inline six -cylinder engine were powered ( designed by Rudolf Schleicher ) with 1173 cc displacement, the at 4000 min - 1 is a power of 30 hp ( 22 kW) gave. The engine power is transmitted via a four-speed gearbox with floor shift to the rear wheels. The top speed of the car was 90 km / h
The front wheels are independently suspended on were at a transverse leaf spring (top) and wishbone ( below), the rigid rear axle of semi- elliptical longitudinal leaf springs. All four wheels were equipped with drum brakes, which were operated by cable.