Transmission identification
m (→Identifying transmissions in the TH350 family) |
(Add text, link; clean up) |
||
| Line 1: | Line 1: | ||
{{develop1}} | {{develop1}} | ||
==Preamble== | ==Preamble== | ||
| − | This page is to acquaint people with the identification of popular North American transmissions based on pan shape, case outline, and OEM numbering. This page also offers overall dimension, gear ratios and number of gears available in each transmission, and originating year, make and model. | + | This page is to acquaint people with the identification of popular North American transmissions based on pan shape, case outline, and OEM numbering and coding. This page also offers overall dimension, gear ratios, and number of gears available in each transmission, and originating year, make, and model. |
==Casting numbers== | ==Casting numbers== | ||
===Date codes=== | ===Date codes=== | ||
| − | The date code format varied, but one | + | The date code format varied, but one commonly used format has a letter followed by two or three numbers. The letter is the month. The next number or two numbers will be the day of the month. The last number is the last digit of the year. |
:Example: '''C124''' | :Example: '''C124''' | ||
:*C = March (A = Jan., B = Feb., etc.) | :*C = March (A = Jan., B = Feb., etc.) | ||
| Line 14: | Line 14: | ||
==Automatic== | ==Automatic== | ||
| − | === | + | ===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 | + | |
| − | + | ===Turboglide=== | |
| + | The Turboglide was a relatively short-lived tranny used in the Chevrolet passenger car line. It basically has little to no performance potential and is not considered to be a particularly reliable or strong transmission. For that reason, the coverage is limited to the following section based closely on a post by 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. | |
| + | <br> | ||
<br> | <br> | ||
| − | 1950-54 Closed driveline, flat modulator | + | 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. |
| − | 1955-57 Open driveline, no modulator | + | <br> |
| − | 1958-62 Open driveline, | + | <br> |
| − | The 1950-62 | + | 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. | ||
| + | <br> | ||
| + | <br> | ||
| + | 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. | ||
| + | <br> | ||
| + | <br> | ||
| + | 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. | ||
| + | <br> | ||
| + | <br> | ||
| + | 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. | ||
| + | <br> | ||
| + | <br> | ||
| + | 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. | ||
| + | <br> | ||
| + | <br> | ||
| + | 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> | ||
| + | |||
| + | ==2-speed== | ||
| + | ===Powerglide=== | ||
| + | The Powerglide (PG) transmission was used in Chevrolet vehicles from 1950 to '73. The cast iron PG was used from 1950-'62. | ||
| + | |||
| + | ====Identifying Cast Iron Powerglides, 1950-1962==== | ||
| + | From [http://www.autotran.us/identifying_1956_to_1967_corvett.html autotran.us] | ||
| + | |||
| + | <blockquote> | ||
| + | 1950-'54 Closed driveline, flat modulator<br> | ||
| + | 1955-'57 Open driveline, no modulator<br> | ||
| + | 1958-'62 Open driveline, threaded modulator<br> | ||
| + | The 1950-'62 cast iron Powerglide is the only GM automatic transmission without a pan! | ||
<br><br> | <br><br> | ||
| − | You have to be able to read the casting code on the bottom of the transmission. It is a three or four digit number about 3/8" high, starting with a letter. "A" is January to "L" which is December, the next one or two digits are from 1 to 31 and the last digit is from 0 to 9. So K306 would be Nov | + | You have to be able to read the casting code on the bottom of the transmission. It is a three or four digit number about 3/8" high, starting with a letter. "A" is January to "L" which is December, the next one or two digits are from 1 to 31 and the last digit is from 0 to 9. So '''K306''' would be Nov. 30th, 1956, or a model year 1957 transmission. '''D47''' would be Apr, 4th, 1957, also a 1957 transmission. Remember, the model year usually breaks around the end of August to early September. |
<br><br> | <br><br> | ||
| − | ''' | + | If the code '''L145''' is on the bottom of the transmission in letters about 3/8" high, it would decode as Dec. 14, 1955, or a model year 1956 transmission. It also would have an open driveline and no modulator. If it is apart, the steel clutch plates would all be 0.070" thick and the frictions would be splined inside instead of the lug style. |
<br><br> | <br><br> | ||
| − | When ordering a 1953 | + | When ordering a 1953-1954 overhaul or rebuilding kit, specify if it is a Chevrolet car or a Corvette (the Corvette has a rear metal clad seal since it has an open driveline). The 1950-1955 Powerglide uses the early internal lug style friction plates, 1956 and up uses the internal spline style friction plates. |
| − | + | ||
| − | + | ||
<br><br> | <br><br> | ||
| − | Identifying 1956 | + | The 1957 is the only PG transmission that has three (3) 0.090" and two (2) 0.070" steel clutch plates, all of the others have five (5) 0.070" steel plates. |
| − | + | </blockquote> | |
| − | '''1956-1967 CORVETTE POWERGLIDE TRANSMISSIONS''' By Rev. Mike Ernst Assisted By Pete Vanish< | + | ====Identifying 1956 to 1967 Corvette and Chevrolet Powerglides (and 1956 to 1962 shift patterns)==== |
| + | From '''1956-1967 CORVETTE POWERGLIDE TRANSMISSIONS''' By Rev. Mike Ernst Assisted By Pete Vanish | ||
| + | <blockquote> | ||
A well-known Corvette parts dealer recently called and said, "I have a customer who needs a 1962 Corvette Powerglide. I have a '62 Powerglide, but how do I show him, or convince him, that it's not just a passenger car version?" | A well-known Corvette parts dealer recently called and said, "I have a customer who needs a 1962 Corvette Powerglide. I have a '62 Powerglide, but how do I show him, or convince him, that it's not just a passenger car version?" | ||
<br> | <br> | ||
My response: "I don't have the foggiest idea!" | My response: "I don't have the foggiest idea!" | ||
<br> | <br> | ||
| − | But at the same time that I received the above inquiry, I purchased the infamous "Miss Piggy," a 1962 Corvette with Powerglide (see Corvette Restorer; Summer, 1985). Also, at about the same time, I purchased a collection of 1956-62 parts that filled the inside of a 15-foot travel trailer. Included among those parts was, you guessed it, a 1962 Powerglide that my brother-in-law had taken out of his 1962, and replaced with a four-speed. How could I determine if it was, or was not, a genuine Corvette transmission? | + | But at the same time that I received the above inquiry, I purchased the infamous "Miss Piggy," a 1962 Corvette with Powerglide (see Corvette Restorer; Summer, 1985). Also, at about the same time, I purchased a collection of 1956-'62 parts that filled the inside of a 15-foot travel trailer. Included among those parts was, you guessed it, a 1962 Powerglide that my brother-in-law had taken out of his 1962, and replaced with a four-speed. How could I determine if it was, or was not, a genuine Corvette transmission? |
<br><br> | <br><br> | ||
I turned to my 1962 Chevrolet Parts Catalog, etc., and to my most knowledgeable source, Pete Vanish of Eau Claire, Wisconsin. Pete must be credited with doing the major portion of the legwork and research for this article, in determining what makes a Corvette Powerglide different than a passenger car version. The intent of this article is primarily to assist you with visual identification, and on occasion I'll reference the transmission internal parts, but primarily I'll deal with external observations. When it comes to externals, there are great differences between Chevrolet passenger car and Corvette Powerglide usage. And there are also differences in Corvette usage between 1956 and 1967. | I turned to my 1962 Chevrolet Parts Catalog, etc., and to my most knowledgeable source, Pete Vanish of Eau Claire, Wisconsin. Pete must be credited with doing the major portion of the legwork and research for this article, in determining what makes a Corvette Powerglide different than a passenger car version. The intent of this article is primarily to assist you with visual identification, and on occasion I'll reference the transmission internal parts, but primarily I'll deal with external observations. When it comes to externals, there are great differences between Chevrolet passenger car and Corvette Powerglide usage. And there are also differences in Corvette usage between 1956 and 1967. | ||
| Line 50: | Line 81: | ||
The major difference between Corvette and non-Corvette for the old cast-iron Powerglides used from 1956 through 1961 is readily noticeable - the transmission tailshaft housing extension is different, and bolted to it is a special cast bracket for transmission attachment to the Corvette's frame crossmember. Both the extension and the bracket are difficult to find! | The major difference between Corvette and non-Corvette for the old cast-iron Powerglides used from 1956 through 1961 is readily noticeable - the transmission tailshaft housing extension is different, and bolted to it is a special cast bracket for transmission attachment to the Corvette's frame crossmember. Both the extension and the bracket are difficult to find! | ||
<br><br> | <br><br> | ||
| − | The Corvette extension contained bosses on the left-hand side that were drilled and tapped for mounting the transmission's floor-shifter. Chevrolet passenger car Powerglides were all controlled by a steering column mounted shifter, and their | + | The Corvette extension housing contained bosses on the left-hand side that were drilled and tapped for mounting the transmission's floor-shifter. Chevrolet passenger car Powerglides were all controlled by a steering column mounted shifter, and their extension housings did not use the mounting bosses. |
<br><br> | <br><br> | ||
| − | It should be noted, however, that by the | + | It should be noted, however, that by the 1960s the Powerglide extension housing service replacement part available from your local dealer (the one you'd buy for a 1957 Bel Air) was, in fact, the Corvette extension containing the cast-in bosses. So there exists the possibility that somewhere out there is a repaired 1955-'57 passenger car Powerglide that has the unique Corvette extension in place. |
<br><br> | <br><br> | ||
| − | There is a slight difference that occurred with this early Corvette Powerglide extension. One version was used for 1956 through 1960; the other version for 1961 only, which by calendar 1962 became the only service replacement part for all 1956 through 1961 Corvette applications. Therefore, we know that they will interchange. The difference is in the speedometer drive gear adapter fitting that attaches to the extension housing. The early fitting was 2-5/8" in length; the 1961 fitting measured just 1-7/8". Both extensions will work on any 1956-61 Corvette, but you need to make certain that you also use the correct length speedometer drive fitting with the corresponding extension. Both of these fittings were also used on various passenger car and truck Powerglides, so you'll need to consult a 1961 or 1962 parts book, and a junk yard, to secure what you need. | + | There is a slight difference that occurred with this early Corvette Powerglide extension housing. One version was used for 1956 through 1960; the other version for 1961 only, which by calendar 1962 became the only service replacement part for all 1956 through 1961 Corvette applications. Therefore, we know that they will interchange. The difference is in the speedometer drive gear adapter fitting that attaches to the extension housing. The early fitting was 2-5/8" in length; the 1961 fitting measured just 1-7/8". Both extensions will work on any 1956-'61 Corvette, but you need to make certain that you also use the correct length speedometer drive fitting with the corresponding extension. Both of these fittings were also used on various passenger car and truck Powerglides, so you'll need to consult a 1961 or 1962 parts book, and a junk yard, to secure what you need. |
<br><br> | <br><br> | ||
Another obvious difference is that the automatic transmission fluid filler tube and dipstick are longer on the Corvette Powerglide, than on the passenger car. | Another obvious difference is that the automatic transmission fluid filler tube and dipstick are longer on the Corvette Powerglide, than on the passenger car. | ||
| Line 61: | Line 92: | ||
Several changes occurred with regard to the shift pattern, also indicating possible changes within the Powerglide main case itself. | Several changes occurred with regard to the shift pattern, also indicating possible changes within the Powerglide main case itself. | ||
<br><br> | <br><br> | ||
| − | The shift patterns are shown, as they would appear on the floor console transmission indicator plate. The initial version used in early-1956 had detents at the Park and Reverse positions | + | The shift patterns are shown, as they would appear on the floor console transmission indicator plate. The initial version used in early-1956 had detents at the Park and Reverse positions, while the second version used on later-1956 through early-1958 added a third detent for the Neutral position. These first two versions used a sequence (front to back) of Reverse, Low, Drive, Neutral and Park. |
<br><br> | <br><br> | ||
A third version began in mid-1958, and extended through 1961. Its shift pattern sequence ran (front to back) Low, Drive, Neutral, Reverse, and Park. It used three detents. | A third version began in mid-1958, and extended through 1961. Its shift pattern sequence ran (front to back) Low, Drive, Neutral, Reverse, and Park. It used three detents. | ||
<br><br> | <br><br> | ||
| − | The fourth pattern was used for 1962, and is what became | + | The fourth pattern was used for 1962, and is what became standard on Powerglide equipped cars. This new pattern was just the opposite of the previous pattern, and its sequence ran (front to back) Park, Reverse, Neutral, Drive, and Low. |
<br><br> | <br><br> | ||
'''1962 Powerglide'''<br> | '''1962 Powerglide'''<br> | ||
| − | + | 1962 saw the introduction of a new aluminum Powerglide transmission to replace, in most cases, the cast iron job. The aluminum unit was used with the Chevy II four and six cylinder engines, as well as with the 250 and 300 horsepower 327 engines in passenger cars and Corvettes. The cast iron Powerglide continued use with the 235 six cylinder and 283 V-8 passenger car engines. | |
<br><br> | <br><br> | ||
| − | + | The aluminum Powerglides were manufactured at Toledo, Ohio, in 1962, and they received a "B" character prefix in the unit identification date of manufacture stamping to indicate Toledo. Initially, these stampings were located on the right front corner of the transmission, covered by the converter cover. During the second week of November, 1961, the stamping location was changed to the right-hand side, on the base of the pan. As illustrated, "B1204N" indicates a Toledo Powerglide manufactured December 4th, during the night shift. | |
<br><br> | <br><br> | ||
| − | Internally, there were significant differences between the lighter aluminum Powerglides built for the Chevy II | + | Internally, there were significant differences between the lighter aluminum Powerglides built for the Chevy II, as opposed to those built for the V-8 engine models. In general, fewer clutch disks and smaller clutch piston areas wouldn't allow these lighter transmissions to survive under the requirements of the larger V-8s. |
<br><br> | <br><br> | ||
| − | Externally in 1962, the major difference was that the passenger cars required a tailshaft extension housing that was 9-3/64" long, while the Corvette required an extension that was 11-1/4" long with three cast-in bosses for floor-shifter mounting. This is the primary difference (see photos). If you were to simply lengthen the driveshaft to compensate for the difference in extension length, the shifter still will not mount to the shorter housing, nor would it come through the floor in the correct position. A bit of help is to locate a 1962 Chevy II Powerglide, because it is of the correct extension length (11-1/4" long). The only problem is that the Chevy II Powerglide transmission was not heavy enough internally to handle the power of the Corvette | + | Externally in 1962, the major difference was that the passenger cars required a tailshaft extension housing that was 9-3/64" long, while the Corvette required an extension housing that was 11-1/4" long with three cast-in bosses for floor-shifter mounting. This is the primary difference (see photos). If you were to simply lengthen the driveshaft to compensate for the difference in extension length, the shifter still will not mount to the shorter housing, nor would it come through the floor in the correct position. A bit of help is to locate a 1962 Chevy II Powerglide, because it is of the correct extension length (11-1/4" long). The only problem is that the Chevy II Powerglide transmission was not heavy enough internally (without modification) to handle the power of the 327ci Corvette engine. |
<br><br> | <br><br> | ||
| Line 95: | Line 126: | ||
<br><br> | <br><br> | ||
| − | Also, the 1964 Powerglide (and possibly later | + | Also, the 1964 Powerglide (and possibly later 1963s) used an external oil cooler. Previous Corvettes had always had an excellent power-to-weight ratio that made an oil cooler unnecessary. The engineers apparently changed their minds, and added a cooler consisting of an aluminum heat exchanger mounted in front of the radiator, with fluid lines routed back to the transmission. The use of this cooler extended through 1967 on all Corvette 327 cubic inch engines, while 427 engines with Powerglide used a heat exchanger located inside the tank of the new heavy-duty copper core radiator. |
<br><br> | <br><br> | ||
'''1965-1967 Powerglides'''<br> | '''1965-1967 Powerglides'''<br> | ||
| − | These are the easy ones! In 1965 the new passenger | + | These are the easy ones! In 1965 the new passenger car body style allowed Chevrolet to equalize transmission output extension lengths at 11-1/4". Since the shifters were bolted to the body floor pan in both the passenger cars and the Corvette, there also is no problem with the bosses for shifter mounting on the extension. So the Powerglide transmission itself (not including linkages, oil filler tube and dipstick) is a direct interchange. |
<br><br> | <br><br> | ||
| Line 106: | Line 137: | ||
<br><br> | <br><br> | ||
| − | I've noticed a renewed increase in Powerglide equipped Corvettes over the past year. I attribute this to three reasons: 1. A number of restorers have finished a body-off restoration on an Fl or heavy duty brakes model, and now that that car's finished, and too nice to use, they're looking for a "driver" for the spouse or themselves. Powerglides tend to be very reliable and not "high-strung." 2. Powerglide Corvettes, if they are still Powerglide equipped, tend to have lived | + | I've noticed a renewed increase in Powerglide equipped Corvettes over the past year. I attribute this to three reasons: <br> |
| + | 1. A number of restorers have finished a body-off restoration on an Fl or heavy duty brakes model, and now that that car's finished, and too nice to use, they're looking for a "driver" for the spouse or themselves. Powerglides tend to be very reliable and not "high-strung."<br> | ||
| + | 2. Powerglide Corvettes, if they are still Powerglide equipped, tend to have lived an easier life than their manual shift counterpart that was more thrashed around by a number of different owners.<br> | ||
| + | 3. In 1962, for example, there were roughly only 1,500 Powerglide Corvettes produced. How many remain? 300? Less? Those older cars were much more easily converted from Powerglide to a four speed than the other way around, and so many were. | ||
<br><br> | <br><br> | ||
'''Editor's Note:'''<br> | '''Editor's Note:'''<br> | ||
| − | Mike's preceding story does not include the 1953-1955 Corvette Powerglide transmissions. | + | Mike's preceding story does not include the 1953-1955 Corvette Powerglide transmissions. Information concerning the Powerglides used in 1953-'55 six cylinder Corvettes was published in the Winter 1982 issue of ''The Corvette Restorer Magazine''. For the 1955 Corvette V-8 Powerglide, it should be mentioned that the output shaft extension housing is the same as the 1955 through 1957 Chevrolet passenger cars, as the 1955 Corvette floor-shifter was mounted to the under-body and therefore did not require the shifter mounting bosses on the extensions as used on 1956 and later Powerglide Corvettes. |
</blockquote> | </blockquote> | ||
| Line 138: | Line 172: | ||
====TH350C==== | ====TH350C==== | ||
| − | There was also a TH350'''C''' version that has a lockup torque converter (TCC). The case has a "C" cast into it, and there will be an electrical plug adjacent to the shifter shaft on the driver side of the tranny. Not to be confused with a TH350 non-lockup tranny with a | + | There was also a TH350'''C''' version that has a lockup torque converter (TCC). The case has a "C" cast into it, and there will be an electrical plug adjacent to the shifter shaft on the driver side of the tranny. Not to be confused with a TH350 non-lockup tranny with a threaded electrical connector on the ''passenger'' side of the case. This is a pressure switch that was used ~1972-'73 for the Transmission Controlled Spark (TCS) system. This disabled the distributor vacuum advance in all gears except high gear, and is a single wire switch threaded into a pressure port near where the cooler lines are located. In the case of this switch, you can either leave it in place, unused- or remove it and plug the port. There have been reports of some TH350 trannys having a temp sender in this area as well. |
====TH250C==== | ====TH250C==== | ||
Your Privacy Choices