Powerglide

The Powerglide is a two speed automatic transmission designed by General Motors. It was available primarily on Chevrolet automobiles from 1950 through the early 1970s, although a few Pontiac models in the 1950s also used this automatic transmission. Canadian Pontiacs also used this unit.This unit was not as useful in the 60s as it is in drag racing now.

When introduced on upper-level Chevrolet models in 1950, the Powerglide represented the first automatic transmission offered in a low-priced automobile; in contrast, Ford did not offer their automatic transmission until 1951, while Plymouth car buyers had to wait until 1954. The transmission was simple and very durable, which satisfied customers. By the mid-1950s, more than half of all new Chevrolets were sold with Powerglide. In 1962, GM started building Powerglides in aluminum (primarily for use in the new model Chevy II, which required a light weight transmission for the compact body) and discontinued the cast iron Powerglides in 1963. A heavy duty version of Aluminum Powerglide was offered for 409 V8 equipped passenger cars, and Chevy light trucks using a 1.76:1 reduction planetary gearset, instead of the usual 1.82:1. With a 3.31 axle, Car and Driver magazine discovered an upshift speed of 76 mph to direct with the 409-4bbl 340 hp engine in a contemporary road test. Most, if not all, of the V8/Powergide transmissions came with the 1.76 gearset.

From 1957 to 1961, Chevrolet also produced the Turboglide automatic transmission, a three-speed automatic whose design was similar to that of updated versions of Buick's Dynaflow. The Turboglide, only offered with V8 engines, was more expensive (by about $50) than the Powerglide and did not have wide acceptance, in part due to failures in 1957-'58 models, which were addressed by a significantly upgraded version for 1959.

Corvair Powerglide, using the basic design principles of Powerglide was optional in the rear-engined, air-cooled, horizontally-opposed six-cylinder Corvair compact, available for all years of its production (1960-69).

Powerglide 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 (the Turbo-Hydramatics were introduced in Buicks and Cadillacs a year before).

Usually, Powerglides were coupled behind small-block Chevrolet V8s and their third-generation inline six- and 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 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 Powerglide lingered on as a low-cost automatic transmission option primarily for six-cylinder Chevrolet Novas and four-cylinder Chevrolet Vegas 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.

Although it is a very old design Powerglide still has a strong following in drag racing due to its strength and simplicity. Powerglides are also popular in mud racing and monster truck racing. If the first few years after introduction, they became known as the "Slip-N-Slide Powerglide" (due to the fluid coupling, as opposed to the mechanical coupling of a clutch-driven gearbox) and the "Positive-Pop transmission." This last is due to the characteristic "bump" or "pop" which occurs as the transmission is put into gear from neutral, and begins to load the driveline.