How to Identify a Powerglide Transmissionby Floyd Drake IIIUpdated July 12, 2023
The Powerglide was Chevrolet's main automatic transmission from 1950 through the mid-1970s, A mechanically sound transmission, it was used in various General Motors cars, like Buicks with a model year around the 1960s.
The transmission underwent little change, major exceptions being a switch from iron to aluminum casting and the addition of manual first and second gears. In 1962, the aluminum models were only used with the 327-cubic-inch engine; by 1963, all Powerglides were aluminum-cast. Identifying a Powerglide is a matter of locating the source code on the transmission block and decoding it to find the Powerglide's year of manufacture.
The Powerglide transmission comes in various configurations depending on its application and usage. The typical bellhousing options range from 2 to 4 choices, offering compatibility with different engines.
When it comes to the turbo option, the Powerglide typically offers 1 to 3 variations to suit the specific needs of racers. The cast iron Powerglide, known for its durability, typically comes in 1 to 2 configurations, making it a popular choice for Chevy II vehicles. In terms of manufacturing locations, the Cleveland plant typically produces 1 to 2 Powerglide models. Racers often opt for the Powerglide transmission due to its reliability and performance.
The tailshaft options for the Powerglide typically range from 1 to 3 variations, offering flexibility in drivetrain configurations. The 27 spline option, with its increased strength, is typically available in 1 to 3 configurations to handle high torque demands.
For those seeking a lightweight option, the aluminum Powerglide typically comes in 2 to 4 variations, offering a balance between performance and weight reduction. The extension housing, with its typical 1 to 2 variations, is an important component of the Powerglide, connecting the gearbox to the drivetrain.
Finally, for heavy-duty applications, the Powerglide typically offers 1 to 2 heavy-duty models built to withstand demanding conditions and higher horsepower outputs.
Identifying a Powerglide Transmission
Identifying a Powerglide transmission involves examining several key components. First, inspect the output shaft, which has a unique length and shape that distinguishes it from other transmissions.
Another clue is the part number, which can often be found on the transmission housing or stamped on a metal tag. Powerglides have undergone various upgrades over the years, so understanding the specific model and any modifications can help determine its features and compatibility with certain vehicles.
Additionally, Powerglides are air cooled, meaning they do not require a transmission cooler connected to the radiator. Examining the pan shapes, such as a cast-iron model with no pan on the bottom or a cast-aluminum model with a removable square pan secured by 14 bolts, can provide further identification. The source code, usually located on the side of the pan, is another valuable reference point.
The vacuum modulator, input shaft, driveshaft, and torque converter are all integral parts of the Powerglide transmission, while its application can be found in various aspects of the drivetrain, driveline, and even drag racing. By considering these factors, you can successfully identify a Powerglide transmission and understand its specific characteristics.
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.
A native of New Haven, Conn., Floyd Drake III began writing in 1984. His work has appeared in the "New Haven Register," Medford's "Mail-Tribune" and the "Ashland Daily Tidings." Drake studied journalism at Southern Connecticut State University. After working as a reporter in Oregon, he is now based back home in New Haven.