Super Turbine 300

The Super Turbine 300 (abbreviated ST-300) was a two-speed automatic transmission built by General Motors. It was used in various Buick, Oldsmobile, and Pontiac models from 1964 through 1969. Oldsmobile called this transmission Jetaway, while Pontiac designated as TempesTorque through 1966 and then Two-Speed Automatic from 1967 to 1969.

Design

The ST300 had a three-element torque converter, a front and rear multiple-disc clutch pack, and a compound planetary gearset with front and reverse brake bands. The unit was cooled with a small auxiliary oil cooler located beneath the engine radiator. It had a die cast aluminum case, and weighed 152 lb (69 kg).

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 first to second at 60-65 mph (99-104 km/h).

From 1964 to 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 two-thirds 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-pith stator was dropped after 1967. Pontiac transmissions did not use this feature.

History

The Super Turbine 300 (Jetaway) was introduced for the 1964 model year to replace the earlier Buick Dynaflow and Oldsmobile/Pontiac Roto Hydramatic automatics. It was the only automatic offered on GM A platform cars (Buick Skylark, Oldsmobile Cutlass, and Pontiac Tempest) through 1966, and was available on the full-sized Buick LeSabre and Oldsmobile Jetstar 88 as a cheaper alternative to the three-speed Turbo-Hydramatic. In 1967, the two-speed automatic was replaced by the three-speed Turbo-Hydramatic in the musclecar versions of the intermediate A-body including the Pontiac GTO, Oldsmobile 4-4-2 and Buick GS-400.

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.