The auto industry took a big step forward in 1935 when General Motors and Fisher Body introduced the one-piece steel roof panel. 

Well into the 1930s, American car bodies featured a strange anachronism that dated back to the horse-and-buggy era. Partly due to tradition, partly due to the limits of steelmaking at the time, cars did not have metal roof panels. Instead, the major portion of the roof was filled with a piece known as a top insert, a rickety assembly of hardwood, wire mesh, fabric, seals, and paint that leaked, squeaked, was time-consuming to manufacture, and added little to the structural integrity of the body shell. As car bodies became more sleek and modern every year, the old wood-and-fabric top insert was a curious throwback.

The opportunity for change arrived in 1932, when Inland Steel of East Chicago, Indiana installed its first 76-inch wide rolling mill. Finally, sheet metal was available in sufficient width and quantity to produce roof stampings in one piece. But first the entire body industry would require readjustment, too: larger, more powerful stamping presses, bigger trucks and rail cars to handle the materials. For the 1935 model year, General Motors and its Fisher Body division were able to offer the innovation on Pontiac, Oldsmobile, and Chevrolet Master models. Aggressively marketed as the Turret Top, GM’s all-steel roof was quieter, tighter, far stronger—and ultimately, faster and cheaper to make than the old wood-composite construction. Naturally, the rest of the automakers followed along as soon as they could.

To promote the Turret Top, the Chevrolet division and its favorite filmmaker, Jam Handy, produced a movie called It’s the Top, which we include here. Like many Jam Handy films of the era, It’s the Top employs what we have called the “first, the earth cooled” method of storytelling. It runs a bit long on the setup, which was more suitable to ’30s moviegoers than to the audience of today. If you want to jump forward to around the five-minute point when the actual automotive material begins, that’s fine with us. But if you’re prepared to enjoy the whole film, that’s okay too. Overall, the film does a good job on the engineering. Video below.

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