The Chrysler Corporation took a bold step in 1960 when it converted its entire model line from traditional body-on-frame to unitized construction. Here’s the engineering project as recorded in an original 1960 factory film.
Chrysler didn’t invent unitized body-frame construction for automobiles, of course. The basic concept dates back to Lancia in the 1920s, if not earlier, while here in the USA, Cord, Nash, and others employed the principle in various forms. Even Chrysler briefly gave it a try with the ill-fated Airflow line of 1934-1937, among a number of manufacturers. But Chrysler does deserve the credit for converting its entire car line, with total production of more than one million cars, to unit construction in a single model year. (Not including Imperial.) It was a brave, bold step in high-volume manufacturing that required a complete overhaul of the carmaker’s engineering and production systems for 1960.
Chrysler also earns the credit, if you will, for inventing the term “Unibody,” its corporate trade name for the design. The handy term quickly attained Kleenex status and became the universal generic term for unit construction. (Plymouth also used the term “Dura-Quiet.”) To make Unibody work, countless processes had to be reinvented, from spot welding (6000-plus welds per body) to anti-corrosion dips. New engineering tools were developed, including clear plastic stress models for polarascope testing as shown in the still shot above.
This original Chrysler film goes in-depth to detail these and other Unibody processes, and also provides a great window into car manufacturing overall circa 1960. For any serious gearhead, it’s more than worth the trip. Enjoy the video.
Excellent video. I never understood before how the clear plastic models were used.
While much of the new technology was a success, the rust proofing wasn’t much so. Standing joke (based in truth) for many years was that rust came installed from the factory.
The original Lincoln Zephyr was consider to be a unibody but it still had a full frame, only it was welded to the body instead of being bolted on like was more commonly done. Chrysler took the next step and eliminated most of the frame, putting the stress on the body itself. As to rust issues, I think all of the US car makers had rust problems well into the 80’s when galvanised steels started being used more and new rust proofing products came onto the market.