General Motors transmissions
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===Hydramatic=== | ===Hydramatic=== | ||
The history of the Hydramatic transmission began back in 1932, when it was introduced by Cadillac as the "shiftless transmission". For more historical information, see [http://en.wikipedia.org/wiki/Hydramatic Hydramatic transmission] at Wikipedia. The scope of this article is mainly centered around the transmissions of the '60s to present date. However, if there is interest in prior years it can certainly be included. | The history of the Hydramatic transmission began back in 1932, when it was introduced by Cadillac as the "shiftless transmission". For more historical information, see [http://en.wikipedia.org/wiki/Hydramatic Hydramatic transmission] at Wikipedia. The scope of this article is mainly centered around the transmissions of the '60s to present date. However, if there is interest in prior years it can certainly be included. | ||
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| + | ===Turbo Glide=== | ||
| + | The following is from Tomcars1 at trifive.com: | ||
| + | |||
| + | <Blockquote> | ||
| + | The Turboglide was a sister transmission to the Buick Dynaflow. There were multiple versions of the Dynaflow throughout it lifetime- but the Turboglide is most closely related to the 1956 and later Triple-turbine Dynaflow , Flite-pitch Dynaflow and the later Buick Turbine drive. The Turboglide- I think- was the first diecast aluminum automatic that GM manufactured- it was for sure the first diecast aluminum automatic from Chevrolet. The Powerglide continued as a cast iron case automatic until 1962 when the Toledo Ohio transmission plant stopped making the Turboglide and began making the aluminum case Powerglide for the Chevy II on the same assembly line.</Blockquote> | ||
| + | <Blockquote> | ||
| + | The difference between the Turboglide and other automatics (except for the Dynaflow) is that the Turboglide has a torque converter with three separate turbines in the one converter case, each of the three turbines are geared to the output shaft with different reduction ratios. Each of the three turbines functioned as a separate 'gear' with slightly overlapping effectiveness. The first turbine had 2.66:1 reduction and was good for starting the car and maxed out speed wise at 30 MPH. The second turbine began transmitting torque from 10 MPH and maxed out at 60 MPH. The third turbine began transmitting torque from about 15 MPH and was a direct drive to the output shaft. What this did was transmit torque from the engine to the output shaft without any 'gear shifting'- all of the torque was transmitted by hydraulic means. | ||
| + | </Blockquote> | ||
| + | <Blockquote> | ||
| + | The 1957 Turboglide was different from the later transmissions in that it used a cone shaped clutch to control the forward/reverse selection planetary gears. Cone clutches have a high surface area-to-space relationship, and have been used in other automatic transmissions and even early 20th. century manual clutches. But they tend to heat unevenly and warp- that is why we no longer have cone clutches for manual shift transmissions. When the Turboglide trans was shifted from forward to reverse while the car was still moving the cone clutch would get hot, warp and wear the friction face away quickly- causing a loss of locking grip and worn clutch material loose throughout the transmission- not a good situation for a long transmission life. | ||
| + | For all intents and purposes the Turboglide is a 3 speed automatic with no apparent shift points. The 1958 and later Turboglide replaced the cone clutch with the more common and durable plate clutches. This resolved the reliability problems- but the image of a problematic transmission was cast. | ||
| + | </Blockquote> | ||
| + | <Blockquote> | ||
| + | The 1957 trans is visually different from the later trans in that it has a pair of cast transmission mounts on its bell housing: large flat surfaces cast at 45 degrees from the horizontal on the underside of the bellhousing. This is because the 1955-'57 Chevys had a perimeter frame and leaf rear springs. These had a 3 point engine/trans mounting system that required a single front engine mount and 2 bellhousing mounts. The 1957 trans is unique in that it also has a long extension housing (tail shaft housing) and a drain plug that the later trans do not. This makes it fairly easy to identify. | ||
| + | </Blockquote> | ||
| + | <Blockquote> | ||
| + | The 1958 and later Turboglides have a very short tail shaft, no mounts on the bell housing and no drain plug in the pan. All of the Turboglide trannys function the same with only detail changes between them to improve reliability. | ||
| + | </Blockquote> | ||
| + | <Blockquote> | ||
| + | They all have a variable pitch (angle of incidence) stator in the center of the torque converter that changes the torque multiplication when the angle is changed. This feature gave the trans the feel of having a 'passing gear' when the throttle was fully depressed- causing he engine RPM to rise by 500-800. This feature could be found in some of the later GM transmissions and was discontinued at the end of the 1970s. | ||
| + | </Blockquote> | ||
| + | <Blockquote> | ||
| + | I do not know the torque ratings for these transmissions- but they were mounted behind the 315HP 348 ci engine in full size Chevys (4500 lbs.) and survived. These are most like a present day hydraulic version of the AUDI/VW DSG dual clutch manual tranny in that more that one 'gear' is engaged at the same time: DSG- 2 gears, Turboglide- 3 gears. | ||
| + | </Blockquote> | ||
| + | <Blockquote> | ||
| + | The Turboglide as well as most of the other GM automatics of the time were phased out in favor of the TH350 and TH400 to reduce complexity and cost and to improve performance and reliability/durability. | ||
| + | </Blockquote> | ||
==General Identification== | ==General Identification== | ||
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