Editing General Motors transmissions (section)
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== Two speed automatic== ===Powerglide=== [[File:CI PG driver1.jpg|thumb|400px|right|Cast iron Powerglide]] The Powerglide transmission was used in Chevrolet vehicles from 1950 to '73. The cast iron PG was used from 1950-'62, the cast iron PG has no bottom pan. From [http://www.autotran.us/pgparts1.html autotran.us]: *1953-'54 Corvette has a rear metal clad seal since it has an open driveline *1955 uses the early internal lug style friction plates *1956-up uses the internal spline style friction plates *1957 is the only cast iron Powerglide that has three (3) 0.090" and two (2) 0.070" steel clutch plates, all others have five (5) 0.070" steel plates *Some 1961, and most if not all 1962 Powerglides use the 12 tang steel clutch plates <br style="clear:both"/> ====Band adjustment==== *Low: 3 turns (with cushion spring) *Low: 4 turns (without cushion spring) *Reverse: 0.250" servo travel ;More at [[Transmission identification]]. ===ST-300=== The 2-speed automatic used in Buick, Olds and Pontiac vehicles was known as the Super Turbine 300 or ST-300. The ST-300 transmission was similar to the Powerglide but few parts were directly interchangeable. The ST-300 was also produced with a variable pitch torque converter. This converter could change stall RPM with an electric solenoid inside the transmission that was activated by a switch usually mounted on the throttle linkage. One positive method to identify this transmission is to notice the fluid port on the stator support shaft. The proper matching Torque Converter will have the corresponding bushings inside the Torque Converter that creates the fluid channel. This fluid channel allows the pressurized transmission fluid to change the pitch of the vanes. [[File:-ST300 Drv Side 1.jpg|frame|left|ST300 left side view shows the electrical connector near the rear of the transmission, that also depicts this as a switch pitch style of transmission.]] [[File:-ST300 Input Shaft2.jpg|frame|right|ST300 input shaft, open port seen on the stator support passes the pressurized transmission fluid to the torque converter and causes the vanes to change pitch at operating speed.]]<br style="clear: both" /> [[File:ST300_TQ_Converter_Pic_1.jpg|frame|left|On the outside of this Torque Converter there are no tell tale signs to depict this converter as a switch pitch style converter. Some converters will have small welded bumps on the outside, yet in this case, this converter does not. ]] [[File:-ST300 TQ Converter Pic 3B.jpg|frame|center|By looking into this converter, you can see the set of narrow bushings that ride upon the stator support that creates a fluid channel that is a pass-through for the pressurized fluid needed to change the pitch of the torque converter vanes.]] ===Torque-Drive=== This was a low cost Powerglide-based transmission that used a manual valve body. It had to be manually shifted into high and down to low. It was sold under RPO MB1, and cost about $100 less than a Powerglide. It was available with 4 cylinder and 6 cylinder engines. ===Dynaflow=== When you say Buick "Dynaflow", it's like saying "Chevy engine". Some still mistakenly refer to the early '60s aircooled Buick Dual Path- as well as ALL Buick trannys up until the Turbo Hydramatic came out, for that matter- as a "Dynaflow". There were a lot of iterations of the Dynaflow- beginning w/the early 1948-'49 version that acted something like a hydraulic version of a CVT tranny (it did have two "speeds"; selecting LOW would get you about 50 MPH, then you manually selected DRIVE). By about 1953 the "Dynaflow" was replaced by the "Twin Turbine Dynaflow", which then became the "Variable Pitch Dynaflow", around 1955. This was followed in 1958 by a triple turbine Dynaflow. There was another short lived tri-turbine AT, the "Turboglide" that was used by Chevy as an option in 1957 until about 1960, known as the Buick "Flight-Pitch" Dynaflow. It lasted until 1959. The different transmissions can be identified by the difference in the shift quadrants; Twin Turbines had a P-N-D-L-R pattern, Triple Turbines were P-R-N-D-G. In 1959 Buick dropped the “Dynaflow” name, the Variable Pitch Dynaflow became the “Twin Turbine”, the Flight Pitch Dynaflow was now called the “Triple Turbine”. 1961 saw the subcompact Buick Skylark/Special come along w/the “Dual Path Turbine Drive”, usually called the “Dual Path”. First gear was only about 1.6:1, so this was a bad design for acceleration if not for the car’s relatively decent power to weight ratio- at least w/the 4bbl V8 215 all aluminum engine- and the torque converter’s relatively high torque multiplication.
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