Back to the Basics: 1937 Film by Chevrolet Explains the Differential

For those who are new to the workings of the automobile, need a refresher or never bothered to learn how anything works rear of the crankshaft, this video may be invaluable to you! Chevrolet Motor Company made a series of informative short films to educate their sales staff in how automotive components work so those employees could better inform the purchasing public. This particular film from 1937 tackles the science of how the ‘modern’ differential allows for smooth vehicle operation in anything other than a straight line.

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Math is hard! So you have to hand it to the film's producers for using motorcycle stunt riders and acrobats to help illustrate the physics involved in making a turn with a car or truck. They really grab your attention while the narrator explains the dynamics involved.

Lots of us old timers know first-hand how a car misbehaves when taking a turn with locked axles. Before posi-traction was widely available or affordable for the average weekend racer, differentials were sometimes welded solid to power both rear wheels rather than just smoke the right-rear tire while the one on the left lazily rolled along for the ride. Because of this, making the turn for the return road at the big end of a drag strip could be as exciting (and dangerous) as the pass you just made.

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Although the video’s content comes from the early part of the last century and modern traction control is often computerized, hot rod and racing applications still use much of the same parts and configurations today. The basic design is simple and trouble free. Always nice to take a stroll down memory lane and see the engineering of yesteryears still in use to this very day.