Editing General Motors transmissions

{{youcanedit}} == GENERAL MOTORS TRANSMISSIONS == == Preamble == The History of the Hydramatic transmission began back in 1932 where it was introduced by Cadillac as the “shiftless transmission”. Anyone want to read about its history should go to this link, http://en.wikipedia.org/wiki/Hydramatic . The scope of this article is mainly centered around the transmissions of the 60’s to present date, however, if there is interest in prior years it can certainly be included. This article will concern itself with the different types of transmissions used by General Motors, and their physical and mechanical properties. First, a transmission is a way of applying torque from an engine through a differential to a wheel, causing forward (or reverse) motion of a standing body. == 1. Types of Transmissions == ==1-A. Standard == == 1-A (1). Three Speed == [[Image:64_Nova_3_sp.jpg‎]] [[Image:64_Nova_3_sp_number.jpg‎]] [[Image:64_Nova_3_sp._shift_levers.jpg‎ ]] From a 1964 Nova 342 Saginaw. == 1-A (2). Four Speed == Manual Transmission Identification & Description [[Image:Muncie_M20_4_speed.jpg‎]] [[Image:Saginaw2.jpg‎]] [[Image:Borgwarner.jpg‎ ]] Muncie (left) Saginaw (center) Borg Warner (right) The Muncie reverse lever is in the extension housing, and the cover has 7 bolts. While looking at the cover, 3rd/4th gear lever is on the left. 1st/2nd gear lever is on the right. The Saginaw reverse shift lever is on the cover, and the cover has 7 bolts. The Borg Warner has a 9 bolt cover. == Borg-Warner == == Muncie == The Muncie 4-speed transmission was used with many different GM models and engine combinations from 1963 through 1974. The basic design and operation theory of the gearbox changed little during this period, however several design upgrades and modifications were made during the total production run. The Muncie was used with most performance engines, and is not to be confused with the Saginaw or Borg Warner 4-speeds. The Muncie is distinguished from the Saginaw in that the reverse lever on the Muncie is mounted in the extension housing, where the Saginaw reverse lever is mounted in the side cover. The main difference between the Muncie and the Borg-Warner is that the Muncie has a 7-bolt side cover and the Borg Warner has a 9-bolt side cover. Muncie 4-speeds were produced in two different ratios wide ratio (M-20) and close-ratio (M-21). An extra heavy duty close-ratio version (M-22) was also offered on many of the big-block high-performance models.The choice of transmission was dictated by the engine size and rear-axle ratio. Axle ratios of 3.73 and lower (numerically higher) came with close-ratio transmissions, while axle ratios of 3.55 and higher (numerically lower) used wide-ratio transmissions. In addition, many GM high-performance engines came with M-22 “Rock-Crusher” in the 1970-73 years, however an early version of the M-22 was available as early as 1965 in Corvettes. Proper identification of the transmission type is absolutely necessary, but sometimes difficult due to several factors. First, GM used several different methods to label and identify transmissions from year to year and model to model. Unfortunately the identification systems seem to have many exceptions, rendering them virtually useless to the restorer. In addition, due to engine and transmission swaps, and modifications that occur over the years many cars do not carry the original drive train that they were produced with. For example, due to interchangeability, a 1969 Pontiac could have a trans case and gears from a Buick and a rear housing (extension) from an Oldsmobile. Several production changes through the years that effect the external appearance may also cause additional confusion when identifying a particular transmission: 1. Both single and dual drain plugs were used. 2. Speedometer adapters were used on either sides of the rear section (extension). 3. Side covers were sometimes secured with studs and nuts, other times with bolts. 4. Input shafts may be fine or coarse spline. Output shafts may be large or small. Combinations of these vary. 5. External shift levers are secured with studs and nuts, others with bolts. Some levers are long and some short. 6. Input shafts may have 1 ring, 2 rings, or no rings at all. Muncie identification (Three 4 speeds were offered.) The M-20 wide ratio, the M-21 close ratio, and the "Extra heavy duty close ratio" M-22, also known as the "Rock Crusher". The M-22 was generally installed behind severely powerful (high torque) big-block 396 and 454 engines. The M-22 is distinguished from an M-21 by the angle of the gear teeth. The M-22 has "straight cut" gears and tends to be noisier.. The M-21 has a higher pitch angle on its gear teeth. The close ratio M-21’s generally came with 3.73 ratio & up cars. While, 3.55 geared & under (numerically lower) cars used the wide ratio gearbox. Due to the wide combination of id's, stampings, numbers, varied and even GM couldn't keep track, it's best to ID your gearbox visually. The best way to ID the transmission is to, count teeth. Muncie 4 speed spline, groove and tooth count characteristics. Type/Year Input Spline Input Groove Input Gear Tooth Count Cluster Gear Tooth Count Output Spline Gear Ratio M20: 1963 - 65 10 none 24 29-22-19-17 27 Note 1 M20: 1966 - 70 10 2 21 25-22-19-17 27 Note 2 M20: 1971 - 74 26 2 21 25-22-19-17 32 Note 2 M21: 1963 - 70 10 1 26 27-22-19-17 27 Note 3 M21: 1971 - 74 26 1 26 27-22-19-17 32 Note 3 M22: 1965 - 70 10 none 26 27-22-19-17 27 Note 3 M22: 1971 - 72 26 none 26 27-22-19-17 32 Note 3 Note 1: M-20 gear ratio: 1st 2.56:1, 2nd 1.91:1, 3rd 1.48:1, 4th direct Note 2: M-20 gear ratio: 1st 2.52:1, 2nd 1.88:1, 3rd 1.46:1, 4th direct, Rev 2.59:1. Note 3: M-21/22 gear ratio: 1st 2.20:1, 2nd 1.64:1, 3rd 1.28:1, 4th direct, Rev 2.27:1 Effective October 21, 1968, an additional letter was added to the plant prefix number to help identify the gear ratios in Muncie transmissions. The additional letter codes as follows: Muncie 3 speed Manual Muncie 4 speed manual transmissions Suffix 1st gear ratio Suffix 1st gear ratio A 3.03:1 A 2.52:1 wide range B 2.42:1 B 2.20:1 close range C 2.20:1 Rock Crusher '''Plant Codes and Prefixes:''' Plant Type Prefix Plant Type Prefix Cleveland Manual Powerglide A Saginaw overdrive O Cleveland Turbo Hydramatic B Warner Gear 3 & 4 speed P Cleveland Powerglide C Muncie 4 speed P Turbo Hydramatic CA Muncie 4 speed R Saginaw Overdrive D Saginaw 4 speed R McKinnon Powerglide E Muncie 3 speed S Muncie 3 speed H Saginaw 3 speed S McKinnon 3 speed K Toledo Powerglide T GM of Canada Turbo Hydramatic L Cleveland Turbo Hydramatic X Muncie 3 speed and Overdrive M Toledo Turbo Hydramatic Y Muncie 4 speed N '''M-20''' M-20 Wide Ratio Cluster gear teeth: 25-22-19-17 Input shaft/gear teeth: 21 '''M-21''' M-21 & M-22 Close-Ratio Cluster Gear teeth: 27-22-19-17 Input shaft/gear teeth: 26 '''M-22''' M-22 “Rock Crusher” Identification The M-22 close-ratio transmission is easily identified internally from the M-20 and M-21 versions by the angle of the gear teeth. (PICTURE) The M-22 was only produced in a close-ratio version, so it will not appear on models with high rear-axle ratios (3.55 or lower numerically) unless someone has changed it. The main internal differences in the 3 types of transmissions are listed in the parts below. • M-20 differs from M-21: Input shaft and Cluster gear • M-20 & M-21 differ from M-22: Input shaft, Cluster gear, First, Second, Third, Reverse idler gear All other components interchange, with the exception of production upgrades and changes. For example, 1963-65 synchronizers, blocking rings, etc. do not interchange with 1966 and newer versions, and therefore the transmission must be stock or interchanged as a unit. == Saginaw == == 1-A (3). Five Speed == == 1-A (5). Six Speed == GM used three basic 6 speed manuals over the years. The ZF S6-40, the Borg Warner/Tremec T56, and the New Process/New Venture NV5600 in trucks '''German ZF S6-40''' Starting with the 1988-96 Y-body (Corvette), a German ZF 6-speed was used, designated S6-40. It was stout and reliable, but its limited use and short production run didn't support wide aftermarket solutions. In fact GM didn't even stock service parts for the transmissions, instead opting to provide remanufactured units instead of repairing them. Although it ended up costing GM less in the long run, it was a concept not warmly received by the public. Early models were rated for 400 ft-lbs, and later models were rated to 450 ft-lbs. ZF 6-speed ratios are as follows: Reverse - 2.50 /First - 2.68 /Second - 1.80 /Third - 1.29 /Fourth - 1.00 /Fifth - 0.75 /Sixth - 0.50 And exploded view of an S6-40 transmission: [[http://i162.photobucket.com/albums/t264/curtis73/explodedZF.jpg]] '''Borg Warner/Tremec T56''' Starting with the 1992/1993 F-body (Camaro, Firebird, Trans Am) the six speed was a Borg Warner-designed, Tremec-built T56 transmission. Although the basic design, case, and internal operation were the same, three different ratio gearsets were available in GM applications. In 1993, F-body cars were equipped with two optional rear axle ratios; 2.73 and 3.23. Beginning in 1994, all T56 cars used the same ratio gearset regardless of rear axle ratio. 1992-1993 T56s with the lower gearsets had a slightly lower torque capacity in the 350 lb-ft range while 1994-later (high) gearsets reduced the sideloads on the case and were rated to 450 lb-ft. T56 use continued like this until 1997 when it also started being used in the Y-body (Corvette) as a rear-mounted transaxle, and continued on in F-bodies behind the LS1 until the end of their production. Of note is the fact that all T56 transmissions share an interchangable main case; even those found in Holdens, Fords, Vipers, and Aston Martins. What differs is the front adapter plate, tailshaft housing, shifter, and input/output shafts. Internally, there were some interchangable differences, like the type of shift forks and syncronizers used, but for the most part, all T56s are built on the same stout center section. Gear ratios are as follows: 1993 F-body, 2.73:1 axle Reverse - 3.28 /First - 3.36 /Second - 2.07 /Third - 1.35 /Fourth - 1.00 /Fifth - 0.80 /Sixth - 0.62 1993 F-body, 3.23:1 axle Reverse - 3.28 /First - 2.97 /Second - 2.07 /Third - 1.43 /Fourth - 1.00 /Fifth - 0.80 /Sixth - 0.62 1994-current GM production ''edit when they quit using it'' Reverse - 2.90 /First - 2.66 /Second - 1.78 /Third - 1.30 /Fourth - 1.00 /Fifth - 0.74 /Sixth - 0.50 A photo of a Tremec T56. Note the multiple options for shifter mounting positions: [[http://i162.photobucket.com/albums/t264/curtis73/tremect56.jpg]] '''NV5600''' Designed by New Venture, this stout truck six speed is up to the task of living behind engines like the Duramax and 8100 Vortec. For obvious reasons it has little application in hotrods due to its huge size, excessive weight, and truck-like gear ratios, but if someone wishes to (''confirm and expand''), please do. A photo of an NV5600. [[http://i162.photobucket.com/albums/t264/curtis73/IMG_1564-copy.jpg]] == 2. Overdrive Units == I never found a better hands-on article with pictures for rebuilding these overdrive units than this one. Check out the link if you need a helping hand: http://www.classictruckshop.com/clubs/earlyburbs/projects/t85n/rebuild.htm == 3. Automatic Transmissions== *'''General Identification''' Transmission Identification By Pan Shape [[Image:Pan_id.jpg‎ ]] {| style="background:yellow" ! Image Number !! Transmission(s) !! Pan Bolts |- ! 1 | Aluminum Powerglide | align = "center" | 14 |- ! 2 | TH200 (Metric), TH200C (Metric) | align = "center" | 11 |- ! 3 | TH250, TH250C, TH350, TH350C, TH375B | align = "center" | 13 |- ! 4 | TH375C, TH400, TH475, 3L80, 3L80HD | align = "center" | 13 |- ! 5 | TH200-4R | align = "center" | 16 |- ! 6 | TH700-4R, 4L60, 4L60E | align = "center" | 16 |- ! 7 | 4L80E | align = "center" | 17 |} Transmission Dimensions [[Image:Transmission_dimensions.jpg‎ ]] Typical Application Information [[Image:Transmission_guidelines.jpg‎]] == 1. Two Speed == == PowerGlide == The Powerglide transmission was used in Chevrolet vehicles, even Corvettes. 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. == 2. Three Speed == == THM-350, THM-350C, THM-375B == the T-350 trans was built in 5 different lengths. Two were 4x4 applications. Tail housing lengths of the two wheel drive were 6 inch , 9 inch and 12 inches. The 12 inch length is not very common. It was used mostly in station wagons of Buick - Oldsmobile brands == THM-400(3L80), THM-375C, THM-475(3L80HD) == == 3. Four Speed == == THM-200-4R == This 200-4r transmission is the same length as a 6 inch tail housing T-350 transmission. The 200-4r requires a TV cable hook up at the EFI - carb with the correct geometry for correct operation. == THM-700R4(4L60) == == 4L60E == 4l60E is an electronic shifted and pressure controlled version of the 700-r4 / 4L60 transmission == 4L80E == == 4. Five Speed == == Comparisons == {{youcanedit}} [[Category:Transmission]]

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