The Super Turbine 300 was a two-speed automatic transmission built by General Motors. It was used in various Buick, Oldsmobile, and Pontiac models from 1964-1969. It was the same transmission marketed under different brand names by each division including ST-300 by Buick, Jetaway by Olds and simply Automatic by Pontiac.
Design
The ST300 had a three-element torque converter, a front and rear multiple-disc clutch pack, and a compound planetary gearset with a front band and a clutch pack for reverse and manual low gear. The unit was either air cooled or cooled with a small auxiliary oil cooler located beneath the engine radiator. It had a die cast aluminum case, and weighed. It was programmed to start in low gear, providing a gear ratio of 1.765:1 plus the additional low-speed multiplication of the torque converter. The shift pattern was Park-Reverse-Neutral-Drive-Low. In Drive at full throttle, it would upshift from low gear to high gear at. Under light throttle, depending on the final drive ratio, it might upshift at 10-15 mph. From 1964-1967, Buick and Oldsmobile versions of this transmission used a torque converter with a variable-pitch stator called Switch-Pitch by Buick and Variable Vane by Olds. The stator blades moved from high to low position by an electrical solenoid and a stator valve, controlled by a switch on the throttle linkage. At light to medium throttle, the stator blades were at 32°, providing a torque multiplication of 1.8:1 and a converter stall speed of approximately 1800 rpm. At ⅔ to full throttle, the blades switched to the 51° high position, giving torque multiplication of 2.45:1 and a stall speed of approximately 2300 rpm. The blades were also set to the high position at idle to limit creep when stopped in Drive. The variable-pitch stator was eliminated after 1967. This feature was not used on the Pontiac versions of this transmission.
History
The Super Turbine 300 was introduced for the 1964 model year as a replacement for the earlier Buick Dynaflow and Oldsmobile/Pontiac Roto Hydramatic transmissions. It was offered on GM A platform cars Buick Skylark, Oldsmobile Cutlass, Pontiac Tempest/Lemans/GTO through 1966, and was available on the full-sized Buick LeSabre and Oldsmobile 88|Oldsmobile Jetstar 88/Delmont 88 as a less expensive alternative to the three-speed Turbo-Hydramatic. If it was used with a V8 motor, the transmission had liquid lines which is cooled by the radiator whereas some of those coupled to V-6 or OHC inline six cylinder engines were air cooled or liquid cooled. This transmission was only produced with the "BOP" bell housing and was never used on any Chevrolet or Chevrolet based engines. From 1967-1969, the Super Turbine 300 was also available on the sporty Pontiac Firebird with the overhead cam inline six or small V8 engines. Some of the rare later ST300's had a bell housing that was cast like a "multi-case", but was never drilled from the factory for the Chevrolet pattern in the United States other than the two lowest bolt holes that are shared, and never installed on any Chevy engine from the factory in the United States. It conceivably could have been drilled for the Chevrolet but there was never a reason to do that as the Powerglide was a strong transmission. The Super Turbine 300 was discontinued entirely after the 1969 model year in favor of the TH400 and lighter TH350 Turbo-Hydramatic, the latter using the Super Turbine 300's tailhousing. Due to its two-speed with torque converter design, the Super Turbine 300 is often confused with Chevrolet's Powerglide — which was also a two-speed torque converter transmission, but the ST 300 was of a completely different design and shared almost no parts with the Chevy unit, which had been around since 1950. The low band was the same as the 1955 up PG along with the same style clutch plates. Correction, the internal operation of the ST300 automatic was similar to the 1962-1971 Powerglide and almost indistinguishable. Some parts were interchangeable. The ST300, used with V-8 engines had additional clutches in the clutch packs, so they could handle the extra power of the larger engines. One of the clutch drums and/or apply piston in the ST300 was often used to 'beef-up' a Powerglide for high performance/racing uses. Chevrolet 'beefed-up' the Powerglide by using a different planetary gear ratio.
