Zbrojovka Z 4

The Zbrojovka Z 4, nicknamed the "Strong Four", is a small passenger car that was produced from 1933 to 1936 by the company Zbrojovka Brno. It became the first Czechoslovak mass-produced car with front-wheel drive. A total of 2,750 cars were produced in five series.

History
In the early 1930s, Zbrojovka Brno produced the Z 9, a car which sales results did not meet expectations. Zbrojovka Brno wanted a car with front-wheel drive, based on a license from the German car manufacturer DKW. Due to the high financial demands, the license was not purchased. Zbrojovka Brno decided to develop a car with the same concept, but without using DKW's patented solutions. The team of designers under the leadership of new chief designer Bořivoj Odstrčil developed the prototype within seven months. It was completed in January 1933. The car, with the advertising nickname "Strong Four", debuted in April 1933 at the Prague Motor Show. The new car was a success, the first 500-piece series was sold out before its production, which began in May 1933. It became the first Czech mass-produced car with front-wheel drive. In the years 1933–1936, four more successively improved series followed. After the production of cars in Zbrojovce, Brno was terminated by the decision of MNO on October 15, 1936, the last cars were sold in 1937. A total of 2,750 units were produced in five production series, making the Z 4 the most successful car of the brand.

In 1934, a series of five racing cars was created using a modified chassis, with an aerodynamic aluminum coupe body. The engines was tuned to an output of 26 KW (35 HP), the cars reached a speed of 130 km/h. Three of the cars participated in the second year of the Czechoslovak 1,000 mile race and won the President's Award for the best factory team. The Mamula-Mašek crew won the category under 1.1 liters at an average speed of 92 km/h.

Series overview

 * Series I – production from April (May) to September 1933, a total of 500 units with Semi-Cabriolet (420 units) and Roadster (80 units) bodies.
 * Series II – modification of the mask and body. Production from June 1933 to October 1936, a total of 750 units with Tudor and Semi-Cabriolet bodies.
 * Series III – engine with increased content (980 cc) and power, body modification. Production from April to November 1934, a total of 500 pieces.
 * Series IV – extending the wheelbase to 2700 mm, rack-and-pinion steering, rounding of the body. Production from August 1934 to October 1936, a total of 500 pieces.
 * Series V – wheelbase extension to 2760 mm, rounding of the body. Production from April 1935 to October 1936, a total of 500 pieces.

Engine and transmission
The Z 4 is powered by an in-line, water-cooled, two-stroke gasoline engine. The engine has a displacement of 908 cm³ (Series I and II) or 981 cm³ (Series III to V). The preparation of the fuel mixture is provided by the Zenith 30 carburetor. The engine is equipped with battery ignition, the electrical installation works with a voltage of 6 V. The engine is cooled by thermosiphon, without a fan.

The engine is located behind the front axle. In front of the front axle, is a three-speed gearbox and a transfer case with a differential. The clutch is a single disc. The engine and gearbox form an assembly unit.

Chassis and body
The chassis is a rigid rectangular frame made of U profiles. The wheels are suspended on independent semi-axles, formed by a transverse lower arm and connected by a transverse leaf spring. Steering is worm or rack (IV and V series). Mechanical drum brakes are on all four wheels. The wheels are steel discs and equipped with 4.50×18" or later 5.25×16" tires.

The cars were supplied with two-door Tudor, Semi-Cabriolet, or Roadster bodies. In addition to factory bodies, individual superstructures were created by individual body builders.

Technical data table
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