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The All Steel Body: The 1930s Development of the Turret Top

By Eric Haartz: The lead photograph, with only a few exceptions, demonstrates the results of a new era in body engineering that was introduced in the early-1930s. From the ascendency of closed-bodied cars in the early 1920s, car makers sought all steel roofs.  The initial attempts with boxy car bodies of that period failed due to air turbulence drumming of the top panel. The drumming phenomenon was similar to what you can still experience by lowering a side window an inch or two while driving. As long as flat car tops remained, the solution was to clothe them in canvas or coated-fabric roof- covers.

As styling dictated more rounded body contours going into the 1930s, the fabric panel on the roof deck receded to the flattest center portion (although full fabric roof-covers could be fitted for decorative effect on higher style cars). These were a big maintenance problem, with residual moisture attacking both fabric and perimeter steel, and even rated mention by Alfred Sloan in Chapter 15 (Styling) of his 1964 book, “My years with General Motors.”

  • Stamped steel turret tops for different body styles in a Chevrolet body stamping plant.  

In 1932 the Inland Steel Company opened America’s first continuous sheet mill capable of making wide sheet steel.  Concurrently Inland and other steel producers introduced steel formulations that allowed deep-draw car body stampings.  These two advancements enabled car makers to make full steel roofs with enough crown to avoid drumming, and in keeping with the styling of that decade.

All-steel sedan and coupe roofs first appeared on 1933 Oldsmobiles as the Fisher Body “Turret Top” and on Willys Overland “Silver Streak” and “Streamline” models.  In the course of the next three years, all of the major car makers followed suit, this Cadillac being typical after the transition ended.

The lead photo is via and courtesy of worldsfair39. The Chevrolet body plant photos are courtesy of the General Motors Archive.

  • Installed stamped all steel turret tops on an assembly line in a Chevrolet body plant. 


17 responses to “The All Steel Body: The 1930s Development of the Turret Top

  1. Very long ago I read that the “turret top” was late in coming, not because there was no capability with presses but that there was considerable customer resistance out of fear that in a crash and fire, that they would be trapped without that flimsy chicken wire to escape through.

    • Contempt is not the only thing that familiarity breeds. Most people are comforted by things and ideas that they are familiar with. Probably the number one reason that so many improvements in automotive design would take a decade (sometimes several decades) before they would be accepted by the buying public.
      I have also read in several sources, that people feared being trapped in enclosed cars. At least once, it was a ’20s source article in a magazine, and exiting through the roof as a safety feature was mentioned.
      Enclosed sedan and coupe automobiles date back to at least 1901 (not counting taxi cabs which electrics go back even further). Yet the idea did not reach real acceptance until well into the 1920s. I believe that 1925 was the first year where more enclosed body new cars were sold than were open cars.

      Thank you again David G, and all.

  2. Great photographs !! Most interesting showing the factory interior pictures.

    In the lead picture, in the foreground on the left, is a 1937 PACKARD Six 115-C, either Business Coupé or Sport Coupé.

    In the same picture, in the center of the parking lot, is a 1937 BUICK and to its right is a 1940 BUICK.

    Also in the lead photograph, parked in the back of the lot, near the white building, is a two-door 1937 CHEVROLET.

  3. David , this was a very interesting read. Thanks for the very informative article. Much of my interest is in prewar automobiles. This was right in my “wheel house” if you will.

  4. Such a collection of delicious cars. One can almost see them as black jellybeans. I had never heard the story of drumming roofs before. Thanks for explanation. The latter 1930s cars certainly were a beautiful design revolution and are still my favorites.

    • I’ve wondered if the 57 Ford had the drumming issue. The 58 Ford has a series of creases running from front to rear on roofs, both sedan and hardtop models. Or, was it “change for the sake of change”?

  5. In the left-hand row I see a 1940 Ford 2-door Sedan (by the split back window) and two vehicles further is a 1939 Chevrolet 2 door sedan. You’d be a lucky man to own that Packard today…or any day for that matter!!

  6. The 1933 Oldsmobiles had fabric roof inserts, the “Turret Top” debuted on the 1935 Chevrolets, Pontiacs and Oldsmobiles.

  7. Another factor in the acceptance of the turret top was, as Michael Lamm points out in his book on automotive styling, the stampings could be stacked, nestled one into another, reducing the cost of shipping to the assembly plant.

  8. There’s a ’34 or ’35 Studebaker Dictator just behind the Packard Coupe. I think the ’35 Studes had a metal insert rather than a turret top, as did the 1935 Hudsons.

    • My 34 Studebaker Dictator 4 Door Sedalia has the fabric top. You are correct that 1935 was the first year for the all steel roof Studebakers.

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