Video: Powerglide Input Shafts 101 From Hughes Performance

GM’s Powerglide transmission hit the showrooms in 1950 but was not as sophisticated as the automatic-shifting transmission that we know today. In the first couple of years, drivers had to manually shift between low and high, which gave the impression of driving a stick but without the clutch. It was clunky and most drivers didn’t like it.

By 1952, the Powerglide was fully automatic and shifted from low to high based on throttle positioning. There was still much to be desired, but Chevrolet pushed ahead with the much-maligned gearbox and by the mid-1950s, more than half of all new Chevrolets were sold with the Powerglide. The Powerglide continued to serve as Chevrolet’s main automatic transmission through the 1960s when a new three-speed Turbo-Hydramatic 400 transmission was put in service.

Pete Nichols explains the various styles of input shafts used by GM in the Powerglide transmissions.

For many GM enthusiasts, the Powerglide was a weak-kneed option and unworthy of any performance car. That attitude was prevalent until hot rodders got involved and strengthened some critical parts with swaps from other transmissions or homemade components. Once the Powerglide gained acceptance from racers and high-performance builders, the doors opened to manufacturers like Hughes Performance to improve on the design.

When equipped with a fluid coupling, the “Slip-N-Slide Powerglide” worked well for street muscle applications while maintaining city manners. The mechanical coupling that became popular with drag racers earned the moniker as the “Positive-Pop” transmission due to the characteristic “pop” when the transmission was shifted from neutral to drive.

Hughes Performance entered the market to build a better mousetrap and make the Powerglide transmission even stronger and more dependable. Combine strength with the transmissions simplistic design and you have an unbeatable combination.

Input shaft splines are the real story when it comes to the Powerglide.

One of the weakest areas in the OE Powerglide was the input shaft. As racers threw more power at the transmission, input shafts sheared and shattered. Everyone using a Powerglide started looking for stronger input shafts. Thankfully, there were manufacturers willing to make these shafts. In the video above, Pete Nichols from Hughes Performance goes through all the different iterations of input shafts used by GM in this two-speed transmission.

GM has not manufactured the two-speed Powerglide for decades but these slushboxes are still very popular with restorers and racing enthusiasts. Thankfully, Hughes Performance makes their own internals and even builds their own housings so enthusiasts don’t have to try and find a donor from a wrecking yard and have it rebuilt. Scarcity has driven up the prices of these junkyard finds to the point where buying a new, purpose-built transmission is an affordable alternative.

For more information on the line of Powerglide transmission manufactured by Hughes Performance, visit them online at hughesperformance.com.

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About the author

Bobby Kimbrough

Bobby grew up in the heart of Illinois, becoming an avid dirt track race fan which has developed into a life long passion. Taking a break from the Midwest dirt tracks to fight evil doers in the world, he completed a full 21 year career in the Marine Corps.
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