Unveiling Redesign Process: The Transmission Squad Commences Fresh Work (Part 2)

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The Toyopet Racer's transmission rebuild has been a unique and challenging journey for the dedicated team of restorers. With the help of seasoned veterans like Kenji Koumaru and Hiroyuki Tamesue, the team has faced and overcome numerous obstacles to bring the vintage car back to life.

One of the most significant challenges was the rebuilding of the manual transmission. Even for veterans like Koumaru and Tamesue, the structure and component shapes posed a unique challenge. The old blueprints mentioned materials no longer in use and did not include dimension tolerances, making it difficult to determine the materials and heat treatment for the new gears and parts.

To tackle this issue, the team sought advice from car production veterans and turned to modern technology. They used a 3D printer to create the mold for the transmission case, a cost-effective and time-saving method. The cast-metal transmission case is the largest component in the transmission rebuild, and outsourcing this piece alone would cost several million yen.

The team also encountered issues during assembly work. Parts running out and components lacking clearance required them to grind certain sections down. The interior of the transmission was severely rusted, and a gear shaft refused to budge, necessitating the use of rust removal techniques and expertise.

Despite these challenges, the team reflect on their experiences and the lessons they learned. They emphasise the importance of manufacturing genba (worksite), designing each part with total vehicle development in mind, and understanding fabrication methods and details beyond the drawings.

Tamesue was involved in the restoration and fabrication of the original transmission as well as the newly built one, finding the new construction to be the harder task. Asuka, a member of the transmission team, believed that all four gears had been functional in the original transmission, and they honored that design by making a shift linkage that skips first and second.

The original Model SD transmission had four forward speeds and one reverse, but for the Toyopet Racer, the specifications indicated third and fourth as forward gears, no reverse, effectively making it a car with only two speeds. The team had to verify the performance requirements of every part based on limited information from cross-sectional drawings and carefully check on details to make necessary adjustments.

The team completed both the original restoration and the new construction of the transmission and is looking forward to the next story focusing on the engine restoration team. The restoration work requires specialized skills and expertise, and Tamesue and other members of the Powertrain Manufacturing Fundamental Engineering Div. are providing significant help to the team.

As the Toyopet Racer's transmission team continues their work, they are not only preserving a piece of automotive history but also demonstrating the importance of perseverance, teamwork, and innovation in the face of challenges. After three months of work, an original transmission for the Toyopet Model SD was discovered, which will aid in the restoration work and vehicle testing. The team is eager to see the car back on the road, ready to race once again.