General Motors transmissions

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by: Alittle1, Cobalt327, Crosley, Curtis73, Foperfoauto, Jon, Mmerlinn, Timothale
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[edit] Overview

This article will concern itself with the different types of transmissions used by General Motors, and their physical and mechanical properties.

Warning Note: Additional info is on the discussion page that has yet to be incorporated into this page.

[edit] Types of transmissions

[edit] Standard

[edit] Three speed

64 Nova 3 sp.jpg 64 Nova 3 sp number.jpg 64 Nova 3 sp. shift levers.jpg

From a 1964 Nova 342 Saginaw.

[edit] 3-speed manual overdrive units

[edit] How overdrive works

The governor powers the solenoid in the mid 20's MPH, you have to let up on the gas pedal to let it shift up. When you push the pedal to the floor the kickdown switch cuts off the power to the solenoid and temporarily cuts off power to the ignition coil so the engine stops running for a second or two. This lets the spring on the solenoid retract and shifts out of overdrive. When you drive less than the governor speed setting in overdrive it cuts off power to the solenoid.

If you are going up a hill and the car does not coast the solenoid will not retract and you will still be locked in overdrive. When you are in overdrive you can not go backwards. This was called the "hill hold" feature.

The pull out T-handle is used to lock up the trans into regular 3-speed mode. This is useful when pulling a trailer uphill and important when going down hill. If the handle is pushed in you can coast and not have any engine braking. When you were cruising and in overdrive second gear and some one pulled along side and wanted to race you could stick your toe under the gas pedal and push down on the kick down switch to gear down before hitting the gas and opening all three carbs.

When you wire in a toggle switch to operate the relay to power the solenoid you could shift it into overdrive in any gear and not have to be above the governor speed in first gear. Just like driving a big truck with a two speed rear end. Just remember you have to let up on the gas to let it shift up into overdrive and when you turn off the switch you also have to let up on the gas to let the spring retract the solenoid to shift out of overdrive. If you leave the switch on and are in overdrive you can not shift into reverse and you cannot roll backwards.

[edit] Borg Warner OD wiring diagram


[edit] Four speed manual transmission identification and description

[edit] T-10 info

See T-10 info at Transmission identification

[edit] Muncie 4-speed

[edit] Muncie 4-speed assembly/parts manual

[edit] Identifying Muncie M20 series transmissions

The external differences between the three Muncie 4 speed transmissions can be deceiving. If the cover is removed, the pitch of the gears can be seen. In order to tell the difference between an M21 and M22 definitively, look at the helix angle on the gearset. M20 and M21 have a steeper pitch, where the M22 will have a less aggressive pitch. M22s are NOT straight-cut or 'spur gears'.

Muncie gearsM20-21 VS M22.jpg

Link to a Muncie page showing Muncie gear ratio, spline counts, exploded view, parts list, etc. from D&L Transmissions.

[edit] M20 or M21/22?

Put the transmission in 1st gear. Turn the input 10 times while counting how many times the output turns. If it turns 2.5 times, its an M20 (2.52 1st gear). If it turns 2.2 times, its an M21 or M22 (2.20 1st).

If you determine it's a close ratio M21 or M22, remove the side cover and look at the angle of the gear teeth (refer to photo above) to see if it's a M22 or not.

[edit] Muncie info from AutoGear:

AutoGear designed the Italian gear program with Antonio Masiero (now Euroricambi). Today there are ways to get over 20 ratios between their M22 and Dragrace M23 programs. AutoGear also makes a 'Muncie Replacement' and replacement parts for GM's Muncie 4-speeds.

To make a strong transmission, use a SuperCase and an Iron Midplate. These 2 things will add a tremendous amount of strength to the transmission. If possible, do not re-use a gearset from the factory case. Factory cases are known to stretch over time and slowly pull the mainshaft gears and countershaft gears out of parallel. This means the gears are 'worn' into each other and will not mesh correctly with new gears or a new case. This leads to a lot of noise and a short lifespan. Use a 26 spline input, hopefully with an oilseal and you could go 27 splines on the mainshaft if its a street car, but it will be stronger with 32 splines on the output.

In most cases there is no sense in using an M21; there are no premium quality gears, and by changing the input and cluster, you get an M20 which has a deeper 1st gear and is better suited to street cars these days. A SuperCase retails for less than $300 and an iron midplate is less than $100. Most shops charge $250 just to repair a used case.

With respect to the M20, M21, and M22; these are technically GM 'RPO' production codes. If you wanted a wide ratio 4-speed it was RPO 'M20' However this code also meant wide a ratio Saginaw or a T10 4-speed, depending on the application and year.

Additionally, M22's are not all 26 spline inputs and 32 spline outputs. The spline count is YEAR specific, not MODEL specific. There are probably more 26 spline input, 32 spline output M20s in the world than any other Muncie 4-speed.

The GM Muncie is stronger than the T10 or ST10. The reason GM went to the T10 after the Muncie 4-speed was dropped in 1974, is because the T10 is less expensive to produce and the horsepower levels had dropped significantly by then. Some guys do impressive things with the T10; however, Richmond Gear was bought out and at the present time (ca. 2012), the availability of T10 parts is getting worse.

[edit] Muncie reference material

[edit] Saginaw 4-speed

[edit] Borg-Warner 4-speed

[edit] Borg-Warner reference material

[edit] Five speed

[edit] GM T-5

BW Model

Original application


1st gear

2nd gear

3rd Gear

4th gear

5th gear
1352-005 1984-'86 Chevette 1.6 L4





1352-010 1982 S10 All





1352-012 1982 S10 2.4 diesel





1352-013 1983 "T" truck 4 & 6 cyl





1352-014 1983 "T" truck 4 cyl all





1352-033 1983 S10 2.0 L4, 2.8 V6





1352-042 1984-'85 S10 2.8 V6





1352-043 1984-'85 S10 2.8 V6





1352-055 1984 S10 1.9 L4 Isuzu





1352-056 1984 S10 2.0 L4





1352-057 1984 S10 1.9 L4 Isuzu





1352-058 1984 S10 2.0 L4, 2.8 V6





1352-101 1985 Minivan 4.3 V6





1352-102 1985-'86 Minivan 2.5 L4, 2.8 V6





1352-107 1985 S10 2.2 L4 diesel





1352-108 1985-'86 S10 2.5 L4, 2.8 V6





1352-110 1985 S10 2.5 L4, 2.8 V6





1352-136 1985 S10 2.2 L4 diesel





1352-145 1985-'86 S10 2.5 L4, 2.8 V6





1352-146 1985 S10 2.8 V6





1352-148 1985 Minivan 4.3 V6





1352-149 1986 Minivan 4.3 V6






[edit] T-5 info and resources

[edit] NV3500

  • 1988–1998 Chevrolet & GMC CK (GMT400 platform) with 4.3 liter V6 and 5.0 liter V8 and 5.7 liter V8. NOTE - some transmissions for the 1988-'92 GMT400 were branded as the MG290 (1987 production year - usually found with the early 1988 GMT400 truck), HM290, 5LM60 (both early (1989-'90) and late version (1991-'92) - late version manufactured by New Venture Gear)
  • 1999–2006 GMC Sierra (GMT800) 1500 and 2500LD
  • 1993–2003 GM S (S10 etc.) trucks with 4.3L V6
  • 1994–2001 Dodge Ram 1500
  • 1994–1995 Dodge Ram 2500 Light Duty
  • 1994-2004 Dodge Dakota

Wide Ratio Gearing Option in Dodge 1500 & GM Full-size Light Trucks:

1 2 3 4 5 R
4.02 2.32 1.40 1.00 0.73 3.55

Close Ratio GM S/T Small Trucks & 2500 Light Duty Dodge Ram Truck Gearing:

1 2 3 4 5 R
3.49 2.16 1.40 1.00 0.73 3.55

[edit] Six speed manual

GM used three basic 6 speed manuals over the years:

  • ZF S6-40
  • Borg Warner/Tremec T56
  • New Process/New Venture NV5600 in trucks

[edit] German ZF S6-40

Starting with the 1988-'96 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 give rise to wide aftermarket support. 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
ZF S6-40 transmission

[edit] Borg Warner/Tremec T56

Starting with the 1992-1993 GM 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 gear sets 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 gear set regardless of rear axle ratio. 1992-1993 T56 with the lower gear sets had a slightly lower torque capacity in the 350 lb-ft range while 1994-later (high) gear sets reduced the side loads 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 interchangeable main case; even those found in Holdens, Fords, Vipers, and Aston Martins. What differs is the front adapter plate, tail shaft housing, shifter, and input/output shafts. Internally, there were some interchangeable differences, like the type of shift forks and synchronizers used, but for the most part all T56 transmissions are built on the same stout center section.

[edit] T56 general info

Tag ID Application Torque Rating 1st 2nd 3rd 4th 5th 6th Rev Input Splines Output Splines
1386-000-003 1992 Dodge Viper 330 2.66:1 1.78:1 1.30:1 1.00:1 0.74:1 0.50:1 2.90:1 26 30
1386-000-005 1993-1995 Dodge Viper 550 2.66:1 1.78:1 1.30:1 1.00:1 0.74:1 0.50:1 2.90:1 26 30
1386-000-006 1993 Camaro/Firebird w/2.73 final drive "M28" 350 3.36:1 2.07:1 1.35:1 1.00:1 0.80:1 0.62:1 3.28:1 26 27
1386-000-007 1993 Camaro/Firebird w/3.23 final drive "M29" 400 2.97:1 2.07:1 1.43:1 1.00:1 0.80:1 0.62:1 3.28:1 26 27
1386-000-009 1994-1995 Camaro/Firebird 450 2.66:1 1.78:1 1.30:1 1.00:1 0.74:1 0.50:1 2.90:1 26 27
1386-000-011 GM Aftermarket 450 2.97:1 2.07:1 1.43:1 1.00:1 0.80:1 0.62:1 3.28:1 26 27
1386-000-012 Mustang 5.0 Aftermarket 450 2.97:1 2.07:1 1.43:1 1.00:1 0.80:1 0.62:1 3.28:1 10 31
1386-000-013 Holden 450 2.66:1 1.78:1 1.30:1 1.00:1 0.74:1 0.50:1 2.90:1 26 27
1386-000-014 1996-2002 Dodge Viper 2.66:1 1.78:1 1.30:1 1.00:1 0.74:1 0.50:1 2.90:1 26 30
1386-000-016 1996-1997 Camaro/Firebird 450 2.66:1 1.78:1 1.30:1 1.00:1 0.74:1 0.50:1 2.90:1 26 27
1386-000-017 1998 Camaro/Firebird 450 2.66:1 1.78:1 1.30:1 1.00:1 0.74:1 0.50:1 2.90:1 26 27
1386-000-018 1996-2002 Dodge Viper 450 2.66:1 1.78:1 1.30:1 1.00:1 0.74:1 0.50:1 2.90:1 26 30
1386-000-019 390 2.66:1 1.78:1 1.30:1 1.00:1 0.74:1 0.50:1 2.90:1
1386-000-020 1999-2002 Camaro/Firebird 450 2.66:1 1.78:1 1.30:1 1.00:1 0.74:1 0.50:1 2.90:1 26 27
1386-000-021 Aston Martin 450 2.66:1 1.78:1 1.30:1 1.00:1 0.79:1 0.63:1 2.90:1 26 30
1386-000-022 Holden Commodore 350 2.66:1 1.78:1 1.30:1 1.00:1 0.74:1 0.50:1 2.90:1 26 27
1386-000-023 Corvette C5 375 2.66:1 1.78:1 1.30:1 1.00:1 0.74:1 0.50:1 2.90:1 26 27
1386-000-024 375 2.66:1 1.78:1 1.30:1 1.00:1 0.74:1 0.50:1 2.90:1
1386-000-025 Corvette Z06 C5 385 2.97:1 2.07:1 1.43:1 1.00:1 0.84:1 0.56:1 2.90:1 26 27
TNET-1077 415 2.97:1 1.78:1 1.30:1 1.00:1 0.74:1 0.50:1 2.90:1
TNET-1247 Dodge Viper 450 2.66:1 1.78:1 1.30:1 1.00:1 0.74:1 0.50:1 2.90:1 26 30
TUET-1259 4.6 Mustang Aftermarket w/mech speedo 450 2.97:1 2.07:1 1.43:1 1.00:1 0.80:1 0.62:1 3.28:1 10 31
TUET-1260 4.6 Mustang Aftermarket w/elec speedo 450 2.97:1 2.07:1 1.43:1 1.00:1 0.80:1 0.62:1 3.28:1 10 31
TUET-1452 Chevrolet Corvette 370 2.66:1 1.78:1 1.30:1 1.00:1 0.74:1 0.50:1 2.90:1 26 27
TUET-1453 Chevrolet Corvette 370 2.66:1 1.78:1 1.30:1 1.00:1 0.74:1 0.50:1 2.90:1 26 27
TUET-1576 Aston Martin 415 2.66:1 1.78:1 1.30:1 1.00:1 0.79:1 0.63:1 2.90:1 26 30
TUET-1660 350 2.66:1 1.78:1 1.30:1 1.00:1 0.74:1 0.50:1 2.90:1 27
TUET-1694 2003-2004 Mustang Cobra 450 2.66:1 1.78:1 1.30:1 1.00:1 0.79:1 0.63:1 2.90:1 26 31
TUET-1806 Dodge Viper SRT-10 550 2.66:1 1.78:1 1.30:1 1.00:1 0.74:1 0.50:1 2.90:1 26 30
TUET-2022 Cadillac CTS-V 2.97:1 2.07:1 1.43:1 1.00:1 0.84:1 0.56:1 2.90:1
TUET-2060 Mustang Cobra 450 2.97:1 2.07:1 1.43:1 1.00:1 0.80:1 0.62:1 3.28:1 10 31
TUET-2062 Dodge Viper 550 2.66:1 1.78:1 1.30:1 1.00:1 0.74:1 0.50:1 2.90:1 26 30
TUET-2066 Pontiac GTO/Holden Monaro 2.97:1 2.07:1 1.43:1 1.00:1 0.84:1 0.56:1 2.90:1 26 27
TUET-5044 Cadillac CTS-V 2.97:1 2.07:1 1.43:1 1.00:1 0.84:1 0.56:1 2.90:1
TUET-6450 T-56 Ford N/A XR6 3.35:1 2.07:1 1.35:1 1.00:1 0.80:1 0.63:1 23 31
TUET-7477 T-56 Magnum Chevy Aftermarket 2.66:1 1.78:1 1.30:1 1.00:1 0.80:1 0.63:1 26 27
TUET-7484 T-56 Magnum Ford Aftermarket 2.66:1 1.78:1 1.30:1 1.00:1 0.80:1 0.63:1 10 31
TUET-8274 T-56 Magnum Ford Aftermarket 2.97:1 2.10:1 1.46:1 1.00:1 0.74:1 0.50:1 10 31
TUET-8277 T-56 Magnum Chevy Aftermarket 2.97:1 2.10:1 1.46:1 1.00:1 0.74:1 0.50:1 26 27

[edit] T56 transmission ratios- 1993 F-body with 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

[edit] T56 transmission ratios- 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

[edit] T56 transmission ratios- 1994-current GM production:

  • Reverse - 2.90
  • First - 2.66
  • Second - 1.78
  • Third - 1.30
  • Fourth - 1.00
  • Fifth - 0.74
  • Sixth - 0.50
T56. Note the multiple options for shifter mounting positions.

[edit] T56 transmission torque specs

  • Backup lamp switch 20 ft/lb
  • Clutch actuator cylinder bolt 71 in/lb
  • Clutch housing bolt 37 ft/lb
  • Control lever handle bolt 18 ft/lb
  • Gear select/skip shift solenoid 30 ft/lb
  • Reverse lockout assembly bolt 13 ft/lb
  • Reverse lockout solenoid 30 ft/lb
  • Shift control bolt 13 ft/lb
  • Shift control closeout Boot Bolt 18 in/lb
  • Shift control knob 27 ft/lb
  • Transmission bolt 37 ft/lb
  • Transmission drain/fill plug 20 ft/lb
  • Transmission mount bolt 38 ft/lb
  • Transmission mount nut 77 ft/lb
  • Transmission support bolt 66 ft/lb
  • Vehicle speed sensor bolt 89 ft/lb

[edit] NV5600

Nv5600 dimens1.jpg
Gear Ratio
  1st 5.63
  2nd 3.38
  3rd 2.04
  4th 1.39
  5th 1.00
  6th 0.73

Designed by New Venture, this stout truck six speed is up to the task of living behind engines like the Duramax and 8100 Vortec. It has a limited application for use in hot rods due to its huge size, excessive weight, and truck-like gear ratios.

There are two versions of the NV5600:
  • The Ram version is rated for 550 lb-ft torque
  • A HD version for larger trucks is rated for 650 lb-ft torque

[edit] Automatic transmissions

GM automatic transmission gear ratios

1st 2nd 3rd 4th Reverse

GM RWD Non-Electronic Transmissions

Earlier transmissions

 1946-'73: See Early GM automatic transmissions


 3-speed 1969-'79


 3-speed 1980-up electronic torque converter lock-up (TCC)


 3-speed 1976-'80


 3-speed 1981-'87 electronic torque converter lock-up (TCC)


 3-speed 1969-'80


 3-speed 1981-'86 lock-up torque converter (TCC)


 3-speed 1964-'98 electric kick down; renamed 3L80


 Overdrive 1981-'90


 Overdrive 1981-'92 electronic torque converter lock-up (TCC); renamed 4L60 during the 1990 model year


 Overdrive 1992-up lock-up torque converter (TCC) GEO Tracker

  GM RWD Computer Controlled Transmissions


 Electronic overdrive 1990-up

4L60E (also 4L65E, 4L70E)

 Electronic overdrive 1993-up; 1996-present has a bolt-on bellhousing


 Electronic overdrive 1991-up full size trucks only (includes Hummer H1, Rolls-Royce, and Jaguar automobiles)


 Electronic overdrive 1999-up (5-speed) Cadillac Catera and CTS, late 2006-2010 Pontiac Solstice and Saturn Sky


 Electronic overdrive 2006-up (6-speed) initially in Corvette, Cadillac XLR-V and Cadillac STS-V


 Electronic overdrive 2005-up (6-speed) Cadillac STS

Allison 1000/2000

 Electronic overdrive 2000-up (5-speed) full size trucks only


 Electronic overdrive 1988-up

  GM FWD Non-Electronic Transmissions


 3-speed 1980-'81


 3-speed 1982-up electronic controlled lock-up torque converter (TCC)


 3-speed 1979-'81 (GM E platform (Eldorado, Toronado, Riviera) and K platform 1980-'85 (Seville)


 Overdrive 1982-'85 electronic controlled lock-up torque converter (TCC); GM E and K platform


 3-speed 1966-'78 (electric passing gear - THM400 derivative) - GM E platform automobiles (Oldsmobile Toronado, Cadillac Eldorado 1967-'78) incl. GMC motorhome


 Overdrive 1985-'92 electronic controlled lock-up torque converter (TCC)


 3-speed 1984-up Geo Prizm and Nova


 3-speed 1985-up Geo Storm, Spectrum & Pontiac Sunburst

  GM FWD Computer Controlled Transmissions


 3-speed 1985-up Geo Metro


 Underdrive 1985-up Geo Prizm and Nova


 Electronic overdrive 1995-up Cavalier, Sunfire, Achieva and Cutlas


 Electronic overdrive 1991-up


 Electronic overdrive 1997-up


 Electronic overdrive 1993-up Northstar


 Electronic overdrive 1990-up Geo Storm


 Electronic overdrive 1991-up Saturn S-Type


 Electronic 5-speed 2002-up Saturn Vue w/V6 and 2003-up Saturn Ion

[edit] 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 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.

[edit] 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

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.

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.

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.

The 1957 trans is visually different from the later trans in that it has a pair of cast transmission mounts on its bellhousing: 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.

The 1958 and later Turboglides have a very short tail shaft, no mounts on the bellhousing and no drain plug in the pan. All of the Turboglide trannys function the same with only detail changes between them to improve reliability.

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.

These transmissions were mounted behind the 315HP 348ci 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.

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.

[edit] General Identification

[edit] Transmission identification by pan shape

Pan id.jpg

Image Number Transmission(s) Pan Bolts
1 Aluminum Powerglide 14
2 TH200 (Metric), TH200C (Metric) 11
3 TH250, TH250C, TH350, TH350C, TH375B 13
4 TH375C, TH400, TH475, 3L80, 3L80HD 13
5 TH2004R 16
6 TH700R4, 4L60, 4L60E 16
7 4L80E 17

Warning Note: Be careful not to mistake a TH250 for a TH350. The TH250 looks almost identical to the TH350 externally- same size, same oil pan. But unlike the TH350, it has a band adjuster stud and lock nut on the passenger side of the case near the cooler lines, similar in design to the Powerglide. The 1979-'84 TH250C used an oil pan with an X-shaped stamped rib (TH350 oil pan is smooth). Usually found in 1974-'75 Chevrolet Vega/Monza (including H-body clones), Nova, Camaro when coupled to the Vega 4 or 250 inline six. Reintroduced in 1979 as an option for GM A, B, F, and G-bodies in response to the failure rate of the THM200 when used behind anything other than a 4 cylinder (coupled to the Buick V6 3800 engine or Chevrolet 90 degree V6 exc. 4.3L) until 1984 (same as the 1974-'75 design but incorporating a lockup torque converter (same as THM350C), a lightened sunshell with 3 or 6 drilled holes (sometimes used in performance applications to decrease ET due to its lower rotating mass), low/reverse piston (with 8 cutouts), and auxillary valvebody (shared with the THM350C). TH250C mostly found in G-bodies (third generation F-bodies came with the TH200C or 700R4) and some B-bodies until the 1984 model year when it was last optioned.

[edit] Transmission dimensions

  • Dimension "A" is the overall transmission length and varies with the length of the extension housing used.
  • Dimension "B" is the length of the main transmission case.
  • Dimension "C" is the distance from the bellhousing to the center of the transmission mounting pad.
    • Note: The mounting pad is usually part of the extension housing, but the graphic shows it on the main case. This means that dimension "C" is usually longer than dimension "B"
  • Dimension "D" is the distance between the center of the mounting bolts - this is the "width" of the mounting pad.
  • Dimension "E" is the width of the transmission at the bellhousing and combined with dimension "B", helps you roughly compare the size of the various transmissions.
Transmission A B C D E Notes
Powerglide 25-23/64" 16-5/16" 20-9/16" 3-3/4" 19" Short shaft
Powerglide 27-9/16" 16-5/16" 20-9/16" 3-3/4" 19" Long shaft
TH350 27-11/16" 21-5/8" 20-3/8" 3-3/4" 19-1/8" 6" extension housing
TH350 30-11/16" 21-5/8" 20-3/8" 3-3/4" 19-1/8" 9" extension housing
TH350 33-27/32" 21-5/8" 20-3/8" 3-3/4" 19-1/8" 12" extension housing
TH400/3L80 28-3/8" 24-5/16" 26-15/16" 4-1/4" 20" 4" extension housing
TH400/3L80 33-27/32" 24-5/16" 27-15/16" 4-1/4" 20" 9" extension housing
TH400/3L80 37-7/8" 24-5/16" 27-21/32" 1-3/4" 20" 13" extension housing
TH700R4/4L60 30-3/4" 23-3/8" 22-1/2" 3-3/4" 20" All, except Corvette
TH700R4/4L60 29-7/8" 23-3/8" 22-1/2" 3-3/4" 20" Corvette, 1982-'92
TH700R4/4L60 29-1/2" 23-3/8" 22-1/2" 3-3/4" 20" With TH350 6" extension housing
TH700R4/4L60 30-1/2" 23-3/8" 28" 3-3/4" 20" (1) Using mount on extension housing p/n 8673406 (old p/n 24214689)
TH2004R 27-11/16" n/a 27" 3-3/4" 19-1/8" Integral extension housing
4L60E 30-3/4" 23-3/8" 22-1/2" 3-3/4" 20" All 1993-'95, except Corvette
4L60E 29-7/8" 23-3/8" 22-1/2" 3-3/4" 20" Corvette, 1993-'95
4L60E 30-3/4" 21-3/4" 23-3/16" 3-3/4" 18-1/4" All 1996-up, except Corvette and LS1
4L60E 31-5/32" 21-3/4" 23-19/32" 3-3/4" 18-1/4" LS1, 1998-up
4L60E n/a n/a n/a n/a n/a Corvette transaxle, 1996-up
4L80E 32-11/16" 26" 30-3/8" 4-1/4" 20" 1991-up, std. duty; 2WD
4L80E 31-11/16" 26" 30-3/8" 4-1/4" 20" 1991-up, heavy duty; 2WD
4L80E 33" 26" 30-3/8" 4-1/4" 20" 1991-up, heavy duty; Long
4L80E 29" 26" 30-3/8" n/a 20" 1991-up, 4WD

(1) An extension housing p/n 8673406 (old p/n 24214689) is available for the TH700R4/4L60 transmission that moves the rear transmission mount to the same position as a TH400 (short-style 4” tail) or TH2004R transmission. This 7-3/8” long extension housing can eliminate transmission crossmember modifications when replacing a TH400 or TH2004R transmission with a 4L60 assembly.

[edit] Typical application information

Transmission guidelines.jpg

[edit] Early GM automatic transmissions

Return to above.


 Hydramatic used in 1946-'63


 Dynaflow (2-speed) used in 1948-'63 Buick only

Cast iron

 Cast iron case Powerglide (2-speed) used in 1950-'62 Chevrolet only

Jetaway 315

 Jetaway 315 used in 1956-'64 Olds, Pontiac, Cadillac, AMC


 TurboGlide used in 1957-'61 Chevrolet only


 FlightPitch used in 1958-'59 Buick only


 Corvair Powerglide (2-speed) used in 1960-'69 Corvair & 1961-'63 Tempest only

Buick Special

 Buick Special used in 1961-'63 Buick Special only

240 RHM

 Roto-Hydramatic 240 used in 1961-'63 Olds F85 only

375 RHM
(Slim Jim)

 Roto-Hydramatic 375 (Slim Jim) used in 1961-'64 Olds, Pontiac


 Aluminum Powerglide (2-speed) used in 1962-'73 Chevrolet only

300 THM

 Super Turbine 300 (2-speed) used in 1964-'69 Buick, Olds, Pontiac

[edit] Two speed automatic

[edit] Powerglide

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.


  • 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

[edit] Band adjustment

  • Low: 3 turns (with cushion spring)
  • Low: 4 turns (without cushion spring)
  • Reverse: 0.250" servo travel
More at Transmission identification.

[edit] 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.

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.
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.

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.
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.

[edit] 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.

[edit] 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.

[edit] Three speed automatic

TH350 accumulator with ID. "72" is year, "152" is a calibration code, "KE" is application code (link to application codes below)

[edit] TH350, TH350C, TH375B

the TH350 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 Buick AND Oldsmobile station wagons.

[edit] TH350 model ID codes

TH350 accumulator with ID. "72" is year, "152" is a calibration code, "KE" is application code (link to application codes below)
ID stamped into governor cover

Codes for 1969-'72 TH350 transmissions are located on the accumulator; 1973-'81 TH350 codes are on the governor cover. Listings of the transmission application codes can be seen HERE.

[edit] ID TH350C

The TH350C input looks different than the TH350 non lockup type tranny. Below is the TH350C input:


A non lockup TH350 input shaft looks like the one shown below:


[edit] TH350 ratios

  • First: 2.52:1
  • Second: 1.52:1
  • High: 1:1

[edit] TH400 (3L80), TH375C, TH475 (3L80HD)

1987-up 3L80HD is the heavy duty version of the TH400 found in light trucks. It has a 27 spline output shaft and is 34.5" long overall in the 2WD version. 'HD' is cast into the bellhousing in medium size letters. The TH400 transmission was used between 1964-1990. 1987 was the year GM transmissions began using the alphanumeric designations.

[edit] TH400 ratios

  • First: 2.48:1
  • Second: 1.48:1
  • High: 1:1

[edit] Switch Pitch

There are SP 400 and SP 300 transmissions. The name "switch pitch" comes from the vanes in the torque converter being able to change their angle (pitch) in order to increase the stall speed to get the vehicle moving easier.

[edit] SP 300

These were found in 1964-'67 and were two-speed. The SP 300 converters are 12". Olds called it the Jetaway, aka the Super Turbine 300.

The ST300 had a three element torque converter, a front and rear multiple disc clutch pack, and a compound planetary gearset with a front band and a clutch pack for reverse and manual low gear. The unit was cooled with a small auxiliary ATF cooler located beneath the engine radiator. It had an aluminum case and weighed 152 lb.

It was designed to start in low gear, providing a gear ratio of 1.765:1 plus the additional torque multiplication provided by the torque converter. The shift pattern was P-R-N-D-L. In Drive at full throttle, it would upshift from low gear to high gear at 60–65 mph.

From 1964-'67, Buick and Olds 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 changed pitch 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 ⅔ to full throttle, the blades switched to the 51° high stall 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 pitch stator was eliminated after 1967. This feature was not used on the Pontiac versions of this transmission.

[edit] SP 400

Switch Pitch (SP) 400 transmissions were available from 1965-'67 in full size Buick, Olds and Cadillac cars. Torque converter diameter is 13".

[edit] SP ID

The easiest way to identify the SP is by the pan shape shown below, right. On the SP 400, there are 3 concave and 1 convex dimples and a 'shoe heel' impression. The shoe heel impression is where the filter picks up fluid and the pickup is shaped just like a shoe heel (see photo above right). Filter is a Wix p/n 51879.


The SP transmission has a two-terminal electrical connector on the driver side of the case. The top terminal is for the SP converter: applying 12 VDC to it caused the converter to go to the higher stall setting. The default no-power position is low stall.

The lower terminal is for the kickdown solenoid. It's operated from the gas pedal or from a switch at the throttle arm of the carburetor.

[edit] Converting TH400 to SP

The SP pump, solenoid and converter can be retrofitted into the early TH400 case. The correct case for this will have a slightly different casting w/a drilled hole present. Later TH400 cases lack this, so the swap isn't possible.

[edit] TH400 model ID codes

A listing of the two letter model code found on the metal ID tag is HERE (no info on Oldsmobile applications).

[edit] Four speed automatic

[edit] TH2004R

The TH2004R transmission is the same length as a 6 inch tail housing TH350 transmission. The TH2004R requires a TV cable hook up at the EFI or carb with the correct geometry for correct operation.

THM 2004R removed from a 1984 Delta 88 (GM B body).

The TH2004R uses a dual pattern bell housing and a 4-way connector. If you are not using the ECM/TCM unit, then there are aftermarket kits sold that will operate the locking converter. Unlike the TH200 which could be a locking or non-locking torque converter, all THM2004R transmissions used a locking converter.

In custom/non original applications, an inexpensive lock up kit will simplify installation, the instructions in the kit are reported as being vague, so further research may be needed.

[edit] TH700R4 (4L60)

[edit] 4L60E

4L60E is an electronic shifted and pressure controlled version of the 700R4/4L60 transmission. Introduced 1993 with the GM truck lineup (GMT400 trucks, G-series vans, M/L van (Astro/Safari), and GMT325 (S-series including the 1993 Typhoon).

  • Early 4L60E resembles the non-electronic 4L60/700R4 but does not have a governor assembly; RH side of transmission case has a green plug which is the main electrical connector.
  • 1995-'97 production 4L60E has a PWM solenoid added to the valvebody - produced until 1997.
    • Some 1996-'97 GMT400s will have the early 4L60E with some overlap since the second design was initially used with the Vortec 4.3L which had a redesigned oil pan that bolts to the transmission bellhousing.

Second design 4L60E introduced in 1996. First use was with 1996+ Vortec 4.3L used with the GM truck/van line. Produced until the 2005 model year when the S-series was phased out.

  • Has a removable bellhousing.
  • Tailhousing has six bolts.

Third design 4L60E introduced in 1997. Replaced the second design where this variant is known as the LSx 4L60E (includes the 4L65 and 4L70).*First used with the fifth generation (C5) Corvette behind the LS1.

  • Has a 7 bolt bellhousing and longer input shaft.
  • When used with the 4.3L the crankshaft pilot was deepened to 1.410" - this also included a redesigned flexplate.

[edit] 4L80E

4L80E is a full electronic controlled and shifted transmission with similar design and strength to the T-400 trans. Early 4L80E and TH400 shared some parts that could be swapped. In 1996 the 4L80E has some design changes in lubrication circuits. You must be very careful when replacing gear train parts in late design 4L80E.

[edit] 6L80E, 6L90E

General Motors 6 speed automatic. While some parts swap between the 6L80 and 6L90, there are differences to watch out for, such as a longer case length for the 6L90 as well as larger output and spline count. Verses the 32 splines of the 6L80.

6L90 transmission.

[edit] Cooler lines

Warning Note: All except TH200C and TH2004R- which are opposite.

  • Top line of the transmission = in from the cooler
  • Bottom line of the transmission = out to the cooler

[edit] TH350 adapters

GM uses an adapter which threads into the case cooler ports and is sealed with a washer. The adapter converts the thread to inverted flare for hard line usage. The cooler ports on the TH350 are usually a female 1/4"-18 NPSM (National Pipe Straight Mechanical (NPSM)) and use a metal washer/seal. The NPSM threads will fit a NPT (tapered) fitting, but if a tapered fitting is to be used, be careful to not over tighten it.

[edit] TH350 fitting torque values

  • Straight pipe fitting- 20 ft/lb
  • Tapered pipe fitting- 15 ft/lb

[edit] TH400 fitting torque values

  • TH400 is 28 ft/lb.

[edit] Bellhousing bolt patterns

The following is a list of GM bellhousing patterns. This section is based on wiki article List of GM bellhousing patterns. Not pictured are the bellhousing patterns used with non-GM engines e.g. Rolls-Royce, Jaguar, and AMC/Jeep.

[edit] Chevrolet pattern

Chevy bolt pattern
  • Chevrolet small and big block V8
  • GM 90° V6 (200/229/4.3L)
  • GM Iron Duke RWD inline 4 (early RWD variants, later versions may use a FWD pattern, and have two possible starter locations)
  • AMC/Jeep with GM Iron Duke inline 4 2.5L/151cid (1980-'83). These use a MOPAR Torqueflite 904 automatic transmission with an integral Chevrolet bellhousing (found in the Jeep CJ and AMC Eagle including the Concord/Spirit). Do not confuse with later AMC 2.5L engine that uses the GM metric pattern (see below).
  • Chevrolet inline 6 (third generation 1962-1990 (Latin America production to 2001)
  • Chevrolet 153 inline 4 (Chevy II, Opala (GM do Brasil), South African-market GM products, pre-Iron Duke, includes the Vortec 3000/181 industrial/marine crate engine)
  • GM Atlas engine

[edit] Buick, Oldsmobile, Pontiac (BOP) V8 pattern

BOP bolt pattern
  • Post-1965 Buick/Oldsmobile/Pontiac RWD V8
  • Buick V8 1967-up
  • Buick pre-3800 90° RWD V6
  • Jeep Dauntless 225cid oddfire V6 (1967-'74)
  • Cadillac cast iron V8 after 1967 (1968-'85 368, 425, 472 and 500cid V8)

Starters are on the driver side on Olds 350-455 and Pontiac, and the passenger side on Cadillac 425/472/500 and Buick 225/231/300/340/350/400/430/455.

[edit] Adapters

TCI and Trans-Dapt make adapter plates for mounting a BOP transmission to a Chevy engine or vice versa. They are plenty sturdy for all but the most demanding circumstances, and the cost is relatively low.

TCI adapter p/n 230001 for Buick, Cadillac, Oldsmobile, Pontiac engines to Chevy transmissions

Wilcap adapter on early Hemi for using TH350 transmission

Wilcap offers an adapter to mount the TH350 tranny to the early Chrysler Hemi (above).

[edit] Uni-bell pattern

This photo shows a multi-pattern case. Both the BOP and Chevrolet pattern on the same bellhousing. First appeared in the mid to late 1960s with the Super Turbine 300. Usage was later widespread with the THM350 (late 1970s - '80s) and a majority of the 200-4R.

Uni-bell pattern

[edit] GM metric pattern

GM 60 degree pattern

The GM metric pattern is also called the GM small corporate pattern and the S10 pattern. This pattern has a distinctive odd-sided hexagonal shape. Rear wheel drive applications have the starter mounted on the passenger side of the block. The 2.2L S10/Sonoma had the starter located in the same position as front wheel drive cars. A rear wheel drive bellhousing is displayed at right.

  • GM 60 degree V6 2.8/3.1/3.4/3.5/3.9L V6 (also used by AMC/Jeep 1984-'86 for the Jeep Cherokee/Comanche XJ and MJ, when optioned with the 2.8L)
  • Buick V6 3300/3800 V6
  • Cadillac 4.1/4.5/4.9L V8
  • Isuzu 3.5L DOHC V6
  • GM Iron Duke/Tech-4 2.5L inline 4
  • GM "122" 1.8/2.0/2.2L inline 4
  • AMC/Chrysler 2.5L inline 4 engine (1984-2002) found in Jeep Cherokee, Comanche, Wagoneer, CJ, 1984-86 DJ-5 (Postal Jeep used by the USPS), Wrangler, and Dodge Dakota (1996-02)
  • GM 5.3L LS4 V8
  • GM 3.5L LX5 V6 "Shortstar"

[edit] Northstar pattern

Northstar pattern, somewhat resembles GM 60 degree pattern

Nearly identical to the GM small corporate/metric pattern, except that the starter is located between the cylinder banks, and the lower right bolt hole is moved outward by roughly one inch. It shares the distinctive odd-sided hexagonal shape of the 60 degree metric pattern.

[edit] GM Ecotec

Ecotec pattern

[edit] Buick Nailhead round pattern

1957 to 1966 364/401/425 Buick Nailhead engines share a unique bellhousing bolt pattern. Will not fit the 264/322 Nailhead engine made from 1953-'56. The 1953-'56 bellhousing/flywheel looks the same as the 1957-'66 Nailheads but they are about 1" larger.

[edit] Buick and Rover aluminum V8 pattern

Buick/Rover aluminum V8 pattern

[edit] Cadillac V8, pre-1968 pattern

Cad 1949-'54 331ci pattern. Note cast in partial bellhousing
Cad 1955-'64 331, 365, 390ci pattern

Early Cadillacs manufactured from 1949 to 1954 used a "round top" bellhousing partially cast into the block casting. Around 1955 the bellhousing pattern was revised until the BOP bolt pattern was adopted.

[edit] Speedometer

[edit] TH350, TH400, manual speedometer gear

[edit] Fastener threads

Using SAE bolts on a GM transmission mount after about 1978 will strip the mount threads. GM converted to metric mount bolts about 1978 even though most of the rest of the transmission bolts did not change until the TH700R4 and TH4L80/E came out.

TH350 and TH400 transmission mount, speedometer, and solenoid bolts went metric about 1978. All other bolts were SAE to the end of production.

TH200C, TH2004R, TH700R4, and later transmissions used metric fasteners.

LX engine transmission to block bolts are metric: M10 x 1.5. Also includes 2001-'02 SBC used in the Chevrolet Express/GMC Savana (crate motors including those for marine/industrial retain the use of SAE bolts).

[edit] Case fluid plugs

[edit] Resources

Crankshaft Coalition Wiki articles

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