#5 How Wits, Not Money, Led to a Pending Patent: Part 1

Now, ladder frames are used in trucks, buses, and certain SUVs designed for rugged conditions, thanks to their sturdiness. Back in the day, they were also found in ordinary passenger cars.

Both the Toyopet Model SD and its progenitor the Model SB truck used ladder frames. Although the blueprints remained in Toyota's archives, it was a tough process converting the original hand-drawn diagrams into 3D data.

The team's biggest challenge was figuring out how to build the ladder frame. Tsunekawa played a central role in that effort.

Ladder frames are typically cast from molds. Unfortunately, making such molds to build a single Toyopet Racer would go against the project's policy of restoring it quickly at a low cost.

Instead, Tsunekawa worked with Watanabe to explore various manufacturing methods that would not require casting. Developing solutions for varied small-volume production is also a challenge for Toyota.

Since they needed to complete a ladder frame first, Tsunekawa and Watanabe were already hard at work figuring out the fabrication particulars while other project members were still in the deliberation phase.

Tsunekawa learned that the frame of Toyota's C+pod, an ultra-compact two-seater BEV, is made using a specialized bending technique by partner company Taiho Seiki. The manufacturer handles everything from prototyping to production of the chassis and suspension components for Toyota vehicles. Tsunekawa hoped his team could take advantage of these techniques and contacted Taiho Seiki about the possibility of creating a ladder frame without molds for the Toyopet Racer.