Powerglide

For other uses, see Powerglide (disambiguation).

Transmission types
Manual Sequential manual Non-synchronous Preselector
Automatic Manumatic
Semi-automatic Electrohydraulic Dual clutch Saxomat
Continuously variable
Bicycle gearing Derailleur gears Hub gears

The Powerglide is a two-speed automatic transmission designed by General Motors. It was available primarily on Chevrolet from January, 1950 through 1973, although some Pontiac models also used this automatic transmission, extensively on models produced for the Canadian market with Chevrolet powertrains. 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.

History

The 1950, 1951, and 1952 Powerglide 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 Powerglides 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 Powerglides in 1963. A heavy duty version of Aluminum Powerglide 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 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. They were introduced in Buicks and Cadillacs the previous year.

Usually, Powerglides 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 Powerglide lingered on as a low-cost automatic transmission option primarily for 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.

Types

There were two primary types or versions of the Powerglide. The Powerglide transmission introduced in 1950 had a cast iron case and is known as the "Cast Iron Powerglide". The "Cast Iron Powerglide" was used until 1963, when it was revamped as "Aluminum Powerglide" where its case and several of its other parts were made of aluminum. The Aluminum Powerglide was used from 1962 until it was replaced with the Turbo-hydramatic series of transmission in 1973. The Aluminum Powerglide is still used today as a racing transmission of choice by many racers mainly for the fact that it only shifts once, and for its extreme durability. It is also possible to purchase all the parts needed to build an Aluminum Powerglide from scratch from most racing parts vendors.

Identification

General Motors transmission have markings to identify;

• - Casting numbers on the case and extension housing.
• - Date Casting Codes
• - Assembly Date Code Stamping - can be stamped anywhere...
• - Chassis Vin Number stamping or "source serial number"- beginning in 1962

Prior to 1967, transmission ID numbers contained the plant prefix code, month and date of production (expressed numerically) and a shift code (D = Day, N = Night). From 1967 on, the ID number contained the transmission type or plant prefix, Date (coded below) and a shift code. The constants in decoding the trans ID number are the date the transmission was produced.

• Pre-67 Example: C213N - (C = Cleveland Powerglide, February 13, Night Shift)
• Post-67 Example: P9E03 - (P = TYPE, 9 = year (1969), E = Month, 03 = Day of Month)

The transmission identification number or source serial number (chassis vin) is usually located close to the transmission code. This number will contain a division identification number, the model year, and the assembly plant and production sequence (last 6 digits) of the vehicle identification number (VIN) stamped onto the transmission.

• Example: 19N500001

Safety issues

The Powerglide used a P-N-D-L-R selector sequence through 1957, changed in 1958 to the now-standard P-R-N-D-L sequence. The earlier sequence had been criticized on safety grounds for placing reverse after a forward gear, instead of having neutral between reverse and the forward ranges. For example, a driver could easily overshoot L and go into R, possibly causing permanent damage and/or catastrophic failure.

Turboglide

From 1957 to 1961, Chevrolet also produced the Turboglide, a triple turbine continuously variable automatic transmission with concurrent ratios whose design was similar to that of Buick's Flight Pitch Dynaflow, subsequently called Triple Turbine (full technical description). 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

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).

Swapping

The Powerglide shares the same length, 27 spline output shaft, and transmission mounting as the THM 350; thus, the transmissions are easily interchangeable for owners wanting three speeds instead of two.

Racing

Although it is a very old design, the 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. In 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.

Currently Robert Campisi from Australia holds the World Record for the fastest run using a Powerglide transmission, clocking 5.95s at 260 mph in his Twin Turbo Ford Mustang in September 2011.

See also

• Turboglide
• Turbo-Hydramatic
• Corvair Powerglide