Powerglide Transmission Historyby Rob Wagner
General Motors produced the two-speed Powerglide automatic transmission mostly for Chevrolet passenger cars and trucks, although some found their way into Pontiacs and Oldsmobiles. GM's Australian subsidiary, GM Holden Ltd., also used the Powerglide in its cars. GM introduced the Powerglide as an automatic transmission option for its low-end cars. It served as the standard automatic transmission from 1950 to 1973.
General Motors was the first of the Detroit automakers to offer an affordable automatic transmission for its cars. Ford introduced its automatic in 1951 and Chrysler in 1954. When a fire damaged GM's Hydramatic automatic transmission factory in 1953, GM fitted its Pontiacs and Oldsmobile with the Powerglide. Although the Powerglide was the first automatic, it wasn't the best by a long shot. GM marketed the Powerglide as a "shiftless" automatic on the 1950 Chevy models, although drivers had to shift one gear. Through 1953, the automatic was sluggish in off-the-line acceleration. It did not automatically shift into high gear, so drivers had a tendency to leave the transmission in low gear too long to about 40 mph to gain adequate acceleration before shifting to high, or second gear. This treatment wreaked havoc on the transmission's components, which led to premature repairs. While drivers had to shift manually into high gear, they loved the idea of driving without using a clutch, third gear and overdrive. By 1955, more than half of all Chevys featured the Powerglide.
The Powerglide from 1950 to 1961 featured a cast-iron case and no oil pan. These early versions have "Powerglide" stamped on the passenger side of the case. The 1962 through 1973 Powerglides were all-aluminum, weighed less than 100 pounds and perfectly matched with the V-8 engine. The new Powerglide was a dramatic improvement over the older transmissions. It had a 14-bolt oil pan and a two-speed automatic shifter that relieved drivers from worrying about when to shift into high gear. Pontiac used a version of the Powerglide for its LeMans and Tempest models. Another Powerglide version matched the rear-mounted engines on the Chevrolet Corvairs. The Powerglide remained the primary automatic transmission on Chevrolets until the three-speed TH350 replaced it in 1973.
Chevrolet used the two-speed Powerglide as optional or standard equipment on all 1963 to 1971 full-size cars and 1972 full-size cars equipped with a six-cylinder engine. Other cars employing the Powerglide were the 1964 to 1972 Chevelle and Malibu, 1967 to 1972 Camaro, 1962 to 1973 Nova, 1962 to 1967 Corvette, 1970 to 1972 Monte Carlo, 1971 to 1973 Vega, 1964 to 1971 full-size pickups and vans and the 1971 to 1972 El Camino utility coupe pickup. Aftermarket installation of the Powerglide in Chrysler cars, AMCs and Fords was common. GM manufactured more than 17 million Powerglides during its production run.
Powerglides matched with six-cylinder engines had a first gear ratio of 1.82-to-1 and a direct gear of 1.00-to-1 for the second gear. Reverse gear ratio was 1.82-to-1. For V-8 models, the automatic had a 1.76-to-1 first gear and 1.00-to-1 second gear ratio. The reverse gear ratio was 1.76-to-1. The case measured 16.3125 inches in length, while total length, including the shaft, was 27.5625 inches.
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