The Powerglide transmission is the first mainstream automatic transmission developed by GM for the Chevrolet line of motor vehicles. It was released for the 1950 model year. At first it wasn’t necessarily an automatic in the way that they are perceived today, but rather a clutch-less transmission that you would still have to shift for yourself. That lasted until the 1953 model year when it became truly automatic. This was achieved by the engineers utilizing a vacuum actuator, and kick down cable. For the 1968 model year and later, the Powerglide was re-branded as the “Torque Drive” transmission. It was intended for use in base model and stripped down models. This version was similar to the original Powerglide introduced for the 1950 model year. It lacked the vacuum control and required the driver to manually shift the transmission themselves. By the time that production eventually ceased, the Powerglide was being phased out by the 3 speed Turbo-Hydramatic 350 and 400. 1973 was the final year that it was an option from the factory. Although they have been out of production for over 4 decades, there is still a healthy aftermarket demand. This is due its bulletproof reputation in the racing community. It was effectively replaced by the TH350.
- First gear- 1.74
- Second gear-1.00 (direct)
- Reverse- 1.76
All non computer controlled automatic transmissions made by GM are going to have the same bell housing. The easiest way to identify a Powerglide would be by the bolt pattern on the pan gasket. It is worth noting that until 1963 it was only produced with cast iron. These transmissions are heavier and only found in the cars they were produced in. They are not a desirable core (unless you are doing a numbers matching restoration) and are generally not offered as a re-manufactured option. They came with both the 16 and 27 spline output shaft. They are the same length as the TH-350, which lends itself well to a very simple swap. In it’s most common form it is 27″ Long with a rear mount 19.5″ from the bellhousing.
The aluminum Powerglide has had a long life in the world of drag racing, monster truck racing, and any application where an extremely reliable and simple transmission is favored. Also, due to its relative simplicity there is little torque loss between the flywheel and the rear wheels.
Drag racers love it because it only shifts once, and in a quarter-mile that is really all that is needed. It is also relatively cheap and inexpensive to repair. That along with its reputation for being bulletproof has cemented its legacy in the racing world.