Turbo-Hydramatic

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Turbo-Hydramatic
Overview
Manufacturer General Motors
Production 1964–
Body and chassis
Class 3-speed longitudinal automatic transmission
Related Turbo-Hydramatic 125
Turbo-Hydramatic 180
Turbo-Hydramatic 425
Chronology
Predecessor Dynaflow
Hydra-Matic
Powerglide
Jetaway
Super Turbine 300
Successor 4L60-E/4L65-E
4L80-E/4L85-E

Turbo-Hydramatic or Turbo Hydra-Matic is the registered tradename for a family of automatic transmissions developed and produced by General Motors. These transmissions mate a three-element turbine torque converter to a Simpson planetary geartrain, providing three forward speeds plus reverse.

The Turbo-Hydramatic or Turbo Hydra-Matic (THM) series was developed to replace both the original Hydra-Matic models and the Buick Dynaflow.[citation needed] In its original incarnation as the Turbo-Hydramatic 400, it was first used in the 1964 model year in Cadillacs.[citation needed] The Buick version, which followed shortly thereafter, was known as the Super-Turbine 400.[citation needed] By 1973, THM units had replaced all of GM's other automatic transmissions including Chevrolet's Powerglide, Buick's Super Turbine 300, and Oldsmobile's Jetaway.[citation needed] Starting in the early 1980s, the Turbo-Hydramatic was gradually supplanted by four-speed automatics, some of which continue to use the "Hydramatic" trade name.[citation needed]

Although the Turbo Hydra-Matic name alludes to the original Hydra-Matic developed by General Motors' Cadillac division in the late 1930s, the two transmissions were not mechanically related.[citation needed]

Super Turbine 400 / THM400 / THM375 / 3L80 / 3L80HD[edit]

Turbo-Hydramatic 400 Transmission

The THM400 can be visually identified by an oil pan number four shown at Transmission Pans. First introduced for the 1964 model year under the name "Turbo Hydra-Matic" in Cadillacs and "Super Turbine" in Buicks.[citation needed] The following year, application expanded to Oldsmobile and Pontiac and to some full-sized Chevrolets.[citation needed] Many of the Buick, Cadillac, and Oldsmobile THM400s produced between 1964-67 were equipped with a "Switch-Pitch" torque converter with a variable-pitch stator, which is sought after by collectors and drag racers.[citation needed] These can be identified outside the vehicle (with the torque converter removed) by a narrow front pump spline.[citation needed] Externally the switch pitch version has two electrical connections, where the non-switch pitch THM400 has only one.[citation needed] GM used a Switch Pitch torque converter in the Buick twin turbine Dynaflow transmission between 1955–1963 and the Super Turbine 300 two speed transmissions used by Oldsmobile Pontiac, and Buick divisions between 1964-1967.[citation needed] This transmission (among other THMs) is identified by the "Park R N D L2 L1" selector quadrant.[citation needed]

A Hydra-Matic 3L80 transmission, produced between 1963 and 1995, at the Ypsilanti Automotive Heritage Museum

A variant of the THM400 known as a THM375 is a THM400 with a long output shaft that mates to the smaller THM350 drive shaft yoke.[citation needed] It can be identified by "375-THM" cast into the tailhousing.[citation needed] Internally the clutch packs originally had fewer[vague] friction plates. Some "Heavy Duty" THM350s were also designated THM375-B.[citation needed] Another variant is the 3L80HD, often referred to as a Turbo 475.[citation needed] The 3L80HD has a straight-cut planetary gear set.[citation needed] There is no externally visible way to determine whether the transmission contains the straight-cut planetary gear set.[citation needed] The THM425 front wheel drive transmission shares almost all its internal parts with the THM400.[citation needed] Checker Motors Corporation Motor Company used the Chevrolet version of the THM400 for its "A" series taxi and Marathon models until the end of production in 1982.[citation needed]

By 1980, the relatively heavy THM400 was being phased out of usage in passenger cars in response to demand for improved fuel economy.[citation needed] The THM 400 was utilized in the C- and K-series (full-size) Chevrolet/GMC pickups and G-series (full-size) vans until 1990 when GM switched over to the 4L80E.[citation needed] Today, the United States Army HMMWV is the only vehicle using the THM400.[citation needed] The civilian Hummer H1 originally had the 3L80s, but the current model has had a 4L80E since the mid-1990s.[citation needed]

Through the end of the '70s substantially more CBOP (Cadillac/Buick/Oldsmobile/Pontiac) bellhousing THM400s were produced than any other THM400.[citation needed] Chevrolet bellhousing THM400s, while not rare, can be hard to find and are, as a result, usually more expensive to buy.[citation needed] The THM400 was never produced with a multicase bell housing.[citation needed]

Other auto manufacturers have used the THM400 and its 4L80E successor,[citation needed] including Ferrari (in the 400/412); Jaguar/Daimler (in pre-1994 XJ12 and XJ-S coupes) and their Daimler stable mates; Rolls-Royce (in 1965–1980 Silver Shadow and 1980-1992 Silver Spirit series cars, along with their Bentley stable mates); the Nissan Prince Royal; AM General; and Jeep (usually found in the FSJ pickups and SUVs). Early Jeep THM400s used an adapter between the engine and transmission bell housing while later models had an AMC specific housing.[citation needed] Though identical except for the bell housing pattern used through the '60s and ending in 1979 the THM400 was mated to the Dana model 18,20 and was the only transmission used with the Borg-Warner 1305/1339 all-wheel-drive transfer case used only in Jeeps, It has been known to adapt a THM400 to other engines using adapters.[citation needed]

THM400 transmissions are very popular in automotive competition due to their great strength.[citation needed] Much of this strength comes from the use of a cast iron center support to suspend the transmission's concentric shafts that join the clutch assemblies to the gear train.[citation needed] The center support, which is splined to the interior of the transmission's case, also provides a robust reaction point for first gear (the gear train's reaction carrier is restrained from counter-rotating the engine in first gear by a roller clutch whose inner race is part of the center support).[citation needed] Since the first gear reactive force is evenly distributed around the periphery of the case, the types of mechanical (and some times violent) failures that have plagued other competition transmissions[vague] are rare.[citation needed]

The THM400 was the first three-speed, Simpson-geared automatic to use overrunning clutches for both first and second gear reaction,[citation needed] a feature that eliminated the need to coordinate the simultaneous release of a band and application of a clutch to make the 2-3 gear change.[citation needed] Owing to this feature, as well as the use of a large, multi-plate clutch to provide second gear reaction, the THM400 is able to withstand very high input torque and an enormous number of shifting cycles, as would be encountered in frequent stop-and-go driving.[citation needed] As a result, it has met with considerable success in commercial vehicle applications.[citation needed]

For 1987, GM changed the nomenclature of their Turbo Hydramatic transmissions — the THM400 was renamed to the '3L80' (three forward speeds, longitudinal positioning, and an arbitrary 'strength' of 80, the second highest such rating assigned). The 3L80HD was introduced in 1987 as the HD unit used in passenger trucks.[citation needed] In 1991, a four-speed overdrive version, the 4L80-E, replaced the THM400 in Chevrolet/GMC pickups, vans, SUVs, and commercial vehicles. The 4L80E (and its successor 4L85E) was the first Hydramatic to incorporate electronic controls — almost all of the THM400/3L80/3L80HD's components are interchangeable.[citation needed]

Transmission fluid cooler line connections are found on the right-hand side of the THM400.[citation needed] The lower connection is the cooler feed, and the upper connection is the return.[1] The case is tapped for either self-sealing 1/4"NPT fittings, or 1/2"UNF fittings with a washer seal. 5/16" or 3/8" rigid coolant lines are generally connected via appropriate double-flared adapters.[citation needed]

4-Wheel drive truck applications used a shorter output shaft that coupled with a female transfer case input shaft.[citation needed] Early transfer cases mated directly to the THM400 with a cast-iron adapter, usually a vertical oval shape.[citation needed] Later models used a circular style iron adapter which is generally considered the stronger of the two.[citation needed]

Gear Ratios are:[citation needed]

  • First Gear - 2.48:1
  • Second Gear - 1.48:1
  • Third Gear - 1.00:1
  • Reverse - 2.07:1

THM350[edit]

The Turbo Hydra-matic 350 was first used in 1969 model cars.[citation needed] It was developed jointly by Buick and Chevrolet to replace the two-speed Super Turbine 300 and aluminium case Powerglide transmissions.[citation needed] So, although it carries the Turbo Hydra-matic name, the Hydra-matic Division of General Motors had little, if anything, to do with its design.[citation needed] The 350 and its 250, 250c, 350c and 375b derivatives have been manufactured by Buick in its Flint, Michigan, plant and by Chevrolet in Toledo and Parma, Ohio, and Windsor, Ontario.[citation needed] Both Chevrolet and Buick divisions produced the THM350.[citation needed]

The THM350 was also regarded as a 'three speed Powerglide' and during its development, was generally called this.[citation needed] Although it uses the same torque converter as the THM400 (without variable pitch stator) it has a familial resemblance to the 1962-'73 Aluminum Powerglide from Chevrolet[according to whom?] and was largely derived from the Chevrolet design.[citation needed] One important difference in the THM350 compared to the THM400 is there is no fixed center support midway through the geartrain, this important difference in layout permitted THM350 to be adapted to the Corvair where the drive and driven ends are the same.[citation needed] This feature was not exploited. Air-cooled versions (with a baffle on the torque converter and air intakes cast into the bellhousing) of the THM350 appeared mid-1972 in Chevrolet Vega and Nova 6.[citation needed]

One THM350 weak point was excessive end-play between the pump and center support and resulting wobble of the direct clutch drum due to both the end play and use of a relatively narrow bushing in the drum.[citation needed] This weak point can be addressed by using an extra thrust washer between the planetary gear and direct clutch to remove the end play and using a wider aftermarket bushing in the direct clutch drum.[according to whom?] Another weak point is the relatively thin center support and the lightweight matching splines in the case.[citation needed] This weakness can be addressed by using an inexpensive aftermarket case saver kit.[according to whom?]

4-Wheel drive truck applications for the THM350 used an iron adapter that mated the THM-350 to the transfer case directly, similar to the THM400. The THM350 adapter was cast iron and used a sliding sleeve to couple the transmission output shaft to the transfer case input shaft with a steel coupler sleeve that was splined to accept both shafts and couple them together. An internal snap ring inside the coupler sleeve controlled the sleeve's position on the shafts, with circular seals in the adapter sealing the transmission from the transfer case.

Around 1980[vague], a lock-up torque converter was introduced; this transmission was phased out in 1984 in GM passenger cars for the 700R4. Chevrolet/GMC trucks and vans used the THM350-C until 1986.[citation needed] The lock-up torque converter was unpopular with transmission builders[citation needed] B&M Racing once marketed a conversion kit for THM350-Cs during the early 1980s until the advent of high stall lock-up torque converters when its overdrive counterpart (THM700R4/4L60) were modified.[citation needed] The standard TH350 is still very popular in drag racing.[citation needed]

THM250[edit]

The THM250 is a derivative of the THM350 and was introduced in 1974 in Chevrolets as a Powerglide replacement.[citation needed] Internally, the THM250 is a THM350 without the intermediate clutch pack with a band adjuster similar to the Powerglide.[citation needed] It was later reintroduced in 1979 as the THM250-C in the wake of the failure-prone THM200/200C.[citation needed] Gear Ratios: THM350,250,250-C

  • 1st: 2.52:1
  • 2nd: 1.52:1
  • 3rd: 1.00:1
  • Reverse: 2.07:1

THM200[edit]

A THM 200 transmission, produced between 1975 and 1987

Right after the 1973 OPEC oil embargo, GM developed a lighter-duty version of the THM350 with lightened materials — primarily alloys in place of ferrous materials (e.g. clutch drums and oil pump),[citation needed] the Turbo-Hydramatic 200. The THM-200 was first used in 1976 models including GM's T-cars and X-cars. However, this transmission was notorious for its failure rate when used behind too large an engine.[citation needed]

Starting with the 1979 model year, vehicles which had the THM-200/200C as standard equipment were optioned with the THM250-C, which is a THM-350 without the intermediate clutch pack along with an adjustable band similar to the Chevrolet Powerglide.[citation needed]

Around 1979, the THM-200 received a lockup torque converter,[citation needed] and some internal components (primarily the low/reverse clutch drum and planetary gears) were later shared with the Turbo-Hydramatic 200-4R.[citation needed]

THM200/200Cs were produced until 1987.[citation needed]

The gearing for the 200C is:[citation needed]

  • First - 2.74:1
  • Second - 1.57:1
  • Third - 1.00:1
  • Reverse - 2.07:1

THM200-4R[edit]

For the 1981 model year, the 200-4R (sometimes called 200R4)[citation needed] was introduced.[citation needed] The components which were prone to failure in the THM200 were improved,[citation needed] and this transmission was used with high-power applications — primarily the Buick Grand National.[citation needed] The 200-4R was configured with several different torque converters and gear ratios depending on the vehicle application.[citation needed]

Unlike the 700R4, most 200-4Rs have a multicase bellhousing for use with Chevrolet, Buick/Olds/Pontiac (BOP), and Cadillac engines.[citation needed] However, 200-4Rs share mounting locations with the TH-400.[citation needed] Since the external dimensions are similar to the TH-350 (overall length, drive shaft yoke spline count/diameter and general size),[citation needed] 200-4Rs are often swapped in place of TH-350s in older vehicles to provide an overdrive gear.[citation needed] Early models had PRND321 on the cluster, while later models had PRN(D)D21, with the left D identified as the overdrive gear by a square or oval ring.[citation needed]

The THM200-4R can be found in the following vehicles:[citation needed]

The THM200-4R was phased out after 1990; its final usage was in the GM B-body vehicles.

The gearing for the 200-4R is:[citation needed]

  • First - 2.7405404:1
  • Second - 1.567567:1
  • Third - 1.00:1
  • Fourth - 0.673913:1
  • Reverse - 2.07:1

THM700R4 / 4L60 / 4L60E / 4L65E / 4L70E[edit]

The four-speed Turbo Hydra-Matic 700R4 was introduced for the 1982 model year for use in Chevrolet/GMC vehicles.[citation needed]

In 1990, the Turbo Hydra-Matic 700R4 was renamed the 4L60.[citation needed] Under the new designation, the "4" stands for the number of forward gears, the "L" for longitudinal applications (rear-wheel-drive), and the "60" is the strength rating (less than the 4L80).[citation needed] "60" is the relative torque value. For example, 80 is stronger than 60, which is stronger than 40, etc.[citation needed] A 4L80-E can handle more torque than a 4L60-E. The "E" denotes electronically controlled shifting. The 4L60 however is hydraulically shifted based on governor pressure and TV cable position.[citation needed] 1992 was the last year of widespread usage of the 700R4 (4L60).[citation needed] 1993 Camaro, Corvette and Typhoon were equipped with the last production 700R4.[citation needed] The last design change of the 700R4 was an added checkball to the valve body.[citation needed]

In 1992 electronic controls were added, and it became the 4L60-E.[citation needed] The 4L60E went into service in trucks, vans, and SUVs in 1993 and in all RWD passenger cars (Corvette, F and B/D bodies) in 1994.[citation needed]

In 2001, an updated version — the 4L65-E, was introduced.[citation needed] Five-pinion planetaries, along with a strength-improved output shaft, were improved to withstand the 300+ lb·ft (400+ N·m) of torque of the 6.0 Vortec engine.[citation needed] The 4L70E transmission is the same as a 4L65E with a speed sensor located in the pump.[citation needed]

700R4 / 4L60 / 4L60E / 4L65E / 4L70E / Technical Description[edit]

The Turbo Hydra-Matic 700R4 can be identified by an oil pan number six shown at General Motors Transmission Pans.

The tailshaft housing is held onto the main case by four bolts (the bolt spacing is similar to the THM350),[citation needed] and uses a square-cut o-ring seal, and not a gasket.[citation needed] The typical width of this transmission where it bolts to the engine is 20 in (51 cm) overall.[citation needed] From the engine/trans mating surface to the cross member mount bolt is 22.5 in (57 cm),[citation needed] and engine/trans surface to output shaft housing mating surface is 23.375 in (59.37 cm) overall,[citation needed] with the tail shaft housing typically measuring 7.625 in (193.7 mm).[citation needed]

Transmission fluid cooler lines on the 700R4 the bottom fitting on the right side of the transmission is the "out" line to the cooler and the top fitting is for the return line from the cooler.[citation needed] These fittings are .25 in (6.4 mm) pipe thread, and can include an adapter from the factory for threaded steel lines in a SAE size.[citation needed] 4L60Es manufactured after 1995 use snap-in connections instead of threaded.[citation needed]

The original version of the transmission had a 27-spline input shaft which was a common failure point.[citation needed] In 1984, the 700R4 designed for use behind Chevrolet small block V8s received a 30-spline input shaft similar to those found on TH400 transmissions and which also used a different torque converter than its 2.8 V6 and 2.2 L4 engines.[citation needed] Between 1984-1987, internal components, from the ring gear to the oil pump housing, were updated, ending with the auxiliary valve body for 700s manufactured after October 1986.[citation needed]

In 1995, the 4L60E received a PWM-controlled lockup converter.[citation needed] The early designs simple on or off lockup function while the later design can variably lock as to not feel the lock up occur.[citation needed] GM added a 5th solenoid to the valve body, called the PWM solenoid.[citation needed]

In 1996, GM introduced a redesigned 4L60E transmission case that incorporated a bolt-on bell (2 piece case, bell and case) housing and an 6 bolt tail housing.[citation needed] This 2 piece case style was first seen in 1996 and up model S-10 Blazer, S-10 Truck, GMC Jimmy, and GMC Sonoma with the 4.3L engine. In the large majority of 1998 & later applications of the 4L60E were 2 piece cases (i.e., a removable bell housing).[citation needed] Both transmissions are the same internally.[citation needed] The non-PWM (1993-1994) style 4L60Es are not interchangeable with PWM-style (1995 and later) 4L60Es.[citation needed] Also in 1996, GM changed the 3-2 solenoid to a different style which makes it not interchangeable with any previous models.[citation needed]

For the model year 1996 GM trucks, there were 2 versions of the 4L60E transmissions.[citation needed] One had a bolt on bell housing the other did not.[citation needed] The bolt on bellhousings used on the 4.3L and 1996-2002 GEN I+ versions of the Small Block Chevrolet used the same bellhousing while the LSx engines used a longer bellhousing to accommodate a redesigned torque converter with a longer pilot nose (GM sells an adapter assembly for using the LSx 4L60-Es when used with an early engine).[citation needed]

The gearing for the 700 is:[citation needed]

  • First - 3.059:1
  • Second - 1.625:1
  • Third - 1.000:1
  • Fourth - 0.696:1
  • Reverse - 2.294:1

(These ratios are commonly rounded off to 3.06, 1.63, 1.00, 0.70, and 2.29).[according to whom?]

700R4 / 4L60 / 4L60E / 4L65E /4L70E Applications[edit]

[2][3]

References[edit]

  1. ^ Sessions, R (1987). How to Work with and Modify the Turbo Hydra-matic 400 Transmission, ISBN 0-87938-267-8, p. 108
  2. ^ Chevrolet/GMC/Geo Transmission Lookup Table, http://www.autorepairmanuals.biz/site/573683/page/372807
  3. ^ Transmission Application Chart, http://www.idatc.com/application_page.htm

External links[edit]