Powerglide - History

History

The 1950, 1951, and 1952 Power Glide transmissions did not automatically shift between low and high (direct drive) which made for very sluggish take-offs and many drivers started in "Low" and shifted to "Drive" at about 30–40 mph (48–64 km/h), which was hard on the transmission. The 1953 and later units when in "Drive" started in low and automatically up shifted to high at a speed determined by the throttle opening. By the mid-1950s, more than half of all new Chevrolets were sold with Powerglide.

In 1962, GM started building Power Glides in aluminum, primarily for use in the new model Chevy II, which required a lightweight transmission for its compact body, and discontinued the cast iron Power Glides in 1963. A heavy duty version of Aluminum Power Glide was offered for passenger cars equipped with the 409 cubic inch V8 engine, and Chevrolet light trucks using a 1.76:1 reduction planetary gear set, instead of the usual 1.82:1. With a 3.31 axle, Car and Driver magazine noted a full-throttle up shift speed of 76 mph (122 km/h) to direct with the 409-4bbl 340 hp (250 kW) engine in a contemporary road test. Most of the V8/Powerglide transmissions came with the 1.76 gear set. One notable exception was the export version of the transmission, which offered only the 1.82 ratio and was used by Holden in Australia behind their Australian built 6-cylinder and V8 engines. Holden vehicles fitted with Chevrolet V8 engines used the 1.76 ratio gear-set.

The Power Glide continued to serve as Chevrolet's main automatic transmission through the 1960s, when a new three-speed automatic transmission called Turbo-Hydramatic 400 (1965 introduction) began to be phased in. They were introduced in Buicks and Cadillacs the previous year.

Usually, Power Glides were coupled behind the small block V8s and the third-generation inline six-cylinder engine and inline four-cylinder engines. By the late 1960s, demand for two-speed automatic transmissions was dwindling as buyers were demanding three-speed units (Ford, Chrysler and American Motors had already switched entirely to three-speed automatics by this time). In 1969, the three-speed Turbo Hydramatic 350 (THM350) was introduced as a light-duty companion to the Turbo-hydramatic 400, and made available on virtually all Chevrolet cars and trucks with six-cylinder or small and medium-sized V8 engines, as well as intermediate sized cars of other GM divisions.

The Power Glide lingered on as a low-cost automatic transmission option primarily for the six-cylinder Chevrolet Nova and four-cylinder Chevrolet Vega until it was phased out after the 1973 model year. They were also used in the DJ-5 'Dispatcher' Jeeps sold for light commercial use, and best known for their service with the US Postal Service.