Development of the model RS Toyopet Crown

Development of a new passenger car started in January 1952 when the return of Kiichiro Toyoda as president was decided. Put in charge of the development was Deputy General Manager of the Body Manufacturing Department Kenya Nakamura. As the person in charge of the manufacturing of Toyota's own 2,000-ton Clearing press machine, he achieved its completion in June 1951 after 10 years of strenuous effort.1

The intention was not to anymore outsource the body design and manufacturing for this new passenger car to a body manufacturer, but to ship completed cars by manufacturing and mounting the body in-house. First the taxi industry, one of the major customers at the time, was surveyed in January 1952, and, also including the results of a market survey by Toyota Motor Co., Ltd., design objectives for a passenger car chassis were drawn up based on the idea that is completely different to appropriating the truck chassis of the past. According to 'The birth of the Toyopet Crown Model RS passenger car' written by Nakamura, the following concrete concepts were decided on:

The first design objective to get started on was to radically improve the SF Model, then on the market, making it a superbly performing car with a low floor and good riding comfort, and without losing its robustness which had been its distinctive feature so far, making it a car with durability on bad road surfaces well. In practical terms this meant the largest possible dimensions possible within the specifications of an American style compact car, a car that feels bright and airy and looks well-made. It weighed 1,200 kilograms, was economical for use as a taxi, had a 1,500 cc engine, remote control transmission, front knee action suspension, a maximum speed of 100 kilometers, and other appealing features.2

Its size was the maximum allowed by the dimension standards for compact cars, and manufacturing of four metal prototypes was started. The car model was signified as the Model RS, and the name had at the suggestion of Kiichiro already been decided on as the Crown.3

Just as manufacturing was about to start, founder Kiichiro Toyoda suddenly passed away on March 27, 1952. The development of a true passenger car was an idea that Kiichiro had nursed for many years, and his death at a time where this was increasingly set to become reality was a great disappointment for the development team.4

The four prototypes to study the car's style were completed in full scale hand-hammered metal by April 23, 1952. Model No. 1 was an American Henry J model, model No. 2 an American Cadillac model, model No. 3 an American Nash model and model No. 4 a British Ford Zephyr model.

Then primary prototypes No.1 and No. 2 were modified and two secondary prototypes were built by June 6 of the same year. Furthermore, a tertiary prototype combining the two secondary prototypes was completed by September 1. The silhouette of the tertiary prototype was so close to the final version so as to be roughly the same, so that the style can be considered to have been finalised by the end of September.

In January 1953 an RS body equipment meeting was held in which arrangements to order welders5 were settled, while investigations into in-house body manufacturing conducted concurrently with product design was promoted. Based on the specifications drawn up during the same month, the design of the Model RS passenger car was embarked on, and in March the trial plans were finished. Following that, 'Matters relating to the RS' was issued6 on April 4 in the joint names of Managing Directors Eiji Toyoda and Shoichi Saito, marking the start of the manufacturing phase of the prototype car.

On May 1 of the same year a reorganization of the engineering departments took effect, and a Project General Manager Department was set up in the engineering division.7 Nakamura, in charge of development of the Model RS, undertook, as Project General Manager, the role of 'driving the process comprehensively forward from engine and car design to production preparation'.

Eight cars-car No. 1 to car No. 8-were built for the primary prototype of the Model RS passenger car. Car No. 1 was completed in June 1953, and based on the results of the running tests that were promptly carried out the 'Main alterations in the primary RS prototype' were drawn up. Next, using the altered version of car No.1 and car No.2, running tests were carried out between alternately Koromo-Shizuoka and back (320 kilometers) and Koromo-Kyoto and back (360 kilometers) in 24 hour shifts over the period from September 15 to October 3. The distance covered by car No.1, including the previous running tests, exceeded 14,000 kilometers.

From February 1954 production of six secondary prototypes (cars No. 11-16) started, incorporating the results obtained from the endurance tests, chassis tests, body tests, benchmarking tests etc. performed on the eight primary prototypes. Between July 12 and August 16, running tests of 20,000 kilometers, which constituted even harsher running conditions than for taxis, were carried out using cars No. 12 and 13. By further improving the prototypes based on these kinds of test results, car No. 16, the last prototype, was of such a high level of completion that it could be used as a sample car for the qualification tests by the Ministry of Transport.

Because the main characteristic of the Model RS passenger car was that its body was manufactured in-house and it was shipped as a completed car, a comprehensive design was aimed for that treats body and chassis as one unit. With regard to manufacturing equipment, plant layouts and equipment design were drawn up through close teamwork between design engineers and production engineers, and the investigations carried out at that point were also reflected in the design details.

In body manufacturing the manual sheet metal working was done away with, and a method was adopted where steel sheets formed in stamping presses were welded together. This called for a great deal of machinery, e.g. stamping presses for sheet metal forming, welding jigs to fix each stamped part, resistance welders and arc welders to join those parts. The cost of body manufacturing equipment up to 1954 amounted to a total of approximately one billion yen, including the extension of the body shop building. Of the one billion yen, 400 million yen was invested in stamping dies alone.8

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