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98-780: The Turbo-Hydramatic or Turbo Hydra-Matic (THM) series was developed to replace both the original Hydra-Matic models and the Buick Dynaflow . In its original incarnation as the Turbo-Hydramatic 400, it was first used in the 1964 model year in Cadillacs . The Buick version, which followed shortly thereafter, was known as the Super-Turbine 400. 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 . Starting in

196-586: A P  R N D 3 2 1 quadrant, while later models used P R N 🄳 3 2 1 . The THM200-4R can be found in the following vehicles: The THM200-4R was phased out after 1990; its final usage was in the GM B-body vehicles. The four-speed Turbo Hydra-Matic 700R4 was introduced for the 1982 model year for use in Chevrolet/GMC vehicles. In 1990, the Turbo Hydra-Matic 700R4 was renamed

294-463: A Hydramatic that would shift perfectly on a summer's day would usually exhibit 2-3 "flare" when cold. Another long-standing driver complaint would be "flare" when trying to get a "3-2" downshift when going around a corner, which usually resulted in a neck-snapping jolt upon band application. From 1939 to 1950, the reverse anchor was used to lock the reverse unit ring gear from turning by engaging external teeth machined into that ring gear. From 1951 on,

392-403: A vehicle to its engine , and which covers and protects the flywheel / clutch or flexplate / torque converter . It derives its name from the bell-like shape that those internal components necessitate. The starter motor may mount to it, and it may support clutch and/or shifter linkage . A Bellhousing may be a separate housing bolted to the gearbox , or it may be an integral portion of

490-454: A "375-THM" or "TH375" identifier. Internally, the clutch packs originally had fewer friction plates. THM375s were found in some 1971-76 Buick Lesabres and Oldsmobile Delta 88s with the 5.7 liter V-8. Somewhere in the Mid-'80s Chevrolet C10 Pickups could also come equipped with a THM375. Some "Heavy Duty" THM350s were also designated THM375-B. Another variant is the 3L80HD, often referred to as

588-509: A Turbo 475. The 3L80HD has a straight-cut planetary gear set. There is no externally visible way to determine whether the transmission contains the straight-cut planetary gear set. The THM425 front wheel drive transmission shares almost all its internal parts with the THM400. Checker Motors Corporation used the Chevrolet version of the THM400 for its "A" series taxi and Marathon models until

686-442: A change of a servo piston from using split Teflon sealing rings to a servo using lip seals. A real problem area was the stamped-steel drive shell, which would strip out, losing reverse. With the 1985 production run, GM started installing a hardened drive shell, but continued to supply the original style until parts inventories were exhausted. Another major problem area was the pump assembly. The pump halves were made of cast aluminum and

784-420: A cone clutch did the same thing when oil pressure was up, and a spring-loaded parking pawl was allowed to lock the same ring gear in the absence of oil pressure. This worked better as the anchor would not grind on the external teeth if that ring gear were turning (that is unless the engine stalled as reverse was engaged). The reverse was obtained by applying torque from the front unit (band on, in reduction) through

882-690: A manual gearbox that could handle the torque of the new Rocket V8 engine. 1948 Oldsmobile Futuramic introduction . One million Hydramatics had been sold by 1949. In the early 1950s various manufacturers without the resources to develop a proprietary automatic transmission bought Hydra-Matics from GM. Users included: In 1952, Rolls-Royce acquired a license to produce the HydraMatic for Rolls-Royce and Bentley automobiles. It continued production until 1967. A massive fire that destroyed GM's Hydra-Matic plant in Livonia, Michigan on August 12, 1953, left

980-473: A market failure of the new transmission. Advertising proclaimed it "the greatest advance since the self-starter ". In 1940, the Hydra-Matic was a US$ 57.00 option ($ 1,240 in 2023 dollars ), rising to US$ 100.00 ($ 2,071 in 2023 dollars ) for 1941. In 1941, it also became an option on Cadillacs for $ 125.00 ($ 2,589 in 2023 dollars ). Almost 200,000 had been sold by the time passenger car production

1078-425: A momentary flare (sudden increase in engine speed) or tie-up (a short period where the transmission is in two gears simultaneously), the latter often contributing to the failure of the front band. Much of the difficulty in staging a "clean" 2-3 or 3-2 shift in any cast-iron Hydramatic was the changing elasticity of the governing springs in the valve bodies. Even ambient temperature would affect this variable, so that

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1176-694: A new source for Hydra-Matic production at Willow Run , Michigan. By the time the 1954 models debuted in late 1953, Hydra-Matic production had returned to normal levels and all '54 model Cadillacs, Oldsmobiles, and Pontiacs with automatic transmissions were once again equipped with Hydra-Matics . Evolving by the pressure of industrial competition from other manufacturers such as Studebaker's three-speed lock-up torque converter co-designed by Detroit Gear (a division of Borg-Warner), named DG 200/250, and Packard 's dual-range two-speed lock-up torque converter coupled Ultramatic , GM's Hydra-Matic underwent several revisions through 1955, before being gradually replaced by

1274-479: A new three-speed torque converter automatic transmission called Turbo-Hydramatic in 1964 and 1965, whose design was more similar in principle to the Chrysler TorqueFlite and the '51 Borg-Warner-designed Ford Cruise-O-Matic than the fluid coupling Hydra-Matic the "Turbo" replaced. The original Hydra-Matic continued to be used in light trucks and other commercial vehicles until 1962. It

1372-499: A non-SP may have one or two (mostly one, except two on vehicles equipped with an internal pressure switch for spark timing retard). A Switch Pitch can be identified outside the vehicle (with the torque converter removed) by a narrow front pump spline. Note: GM had also used a Switch Pitch in the 1955–1963 Buick twin-turbine Dynaflow and the 1964-1967 two-speed Super Turbine 300 used in Buick and Oldsmobile (Pontiac's ST300 didn't get

1470-533: A redesigned 4L60E transmission case that incorporated a bolt-on bellhousing and a six-bolt tail housing. This two-piece case style was first seen in 1996 and up model S-10 Blazer , S-10 pickup, GMC Jimmy , and GMC Sonoma with the 4.3 L engine. The majority of 1998 and later applications of the 4L60E were two-piece cases (i.e. a removable bellhousing). Both transmissions are the same internally. The non-PWM (1993-1994) style 4L60Es are not interchangeable with PWM-style (1995 and later) 4L60Es. Also in 1996, GM changed

1568-402: A routine maintenance item that later versions did not. Early 1940 model Oldsmobiles with Hydra-Matic Drive could be started with the transmission selector lever in any position. The car would then start to move unless the transmission lever had been left in N, neutral. The all cast-iron Hydramatic was the heaviest automatic transmission ever produced for automobiles. The heaviest of them all

1666-660: A selector quadrant similar to Chevrolet's Powerglide in that there was only one "Drive" position and a "Low", although it was a true three-speed unit. This was improved upon for all 1965 models with the "D L2 L1" or "D S L" quadrant, which allowed "dual range" flexibility as did the Dual-Range Hydramatic of 1953–1955. It was this version that replaced all Roto Hydramatic and Controlled-Coupling Hydramatic models in GM cars in that year, ending twenty-four years of four-speed automatic transmission production that obviated

1764-634: A slight redesign for 1998. The LSx engines used a longer one to accommodate a redesigned torque converter, commonly referred to as a 300mm converter, with a longer pilot nose (GM sells an adapter assembly for using the LSx 4L60Es when used with an early engine). There are two bellhousings for the Holden GM models. One for the Corvette drivetrain. One for the S/T platform with 2.2L and 3.8L engines. And finally, two for

1862-407: 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. For the 1981 model year, a lock-up torque converter was introduced which coincided with the new EMC control of most GM cars; this version

1960-488: A variety of transmissions, the most notable of which is the Turbo Hydra-Matic from the 1960s to the 1990s. The Hydramatic used a two-element fluid coupling (not a torque converter , which has at least three elements, the pump, turbine, and stator although Roto Hydra-Matic has a fluid coupling and a fixed stator) and three planetary gearsets , providing four forward speeds plus reverse. Standard ratios for

2058-402: A washer seal. 5/16" or 3/8" rigid coolant lines are generally connected via appropriate double-flared adapters. Four-wheel drive truck applications used 3 various shorter output shafts that coupled with a female transfer case input shaft. Early transfer cases mated directly to the THM400 with a cast-iron adapter, usually a vertical oval shape. Later models used a circular style iron adapter which

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2156-879: Is generally considered the stronger of the two. The shortest was used with the NP203 transfer case. The Turbo Hydra-matic 350 was first used in 1969 model cars. It was developed jointly by Buick and Chevrolet to replace the two-speed Super Turbine 300 and aluminum-case Powerglide transmissions. 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. 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. The THM350

2254-422: Is hydraulically shifted based on governor pressure and throttle valve (TV) cable position. 1992 was the last year of widespread usage of the 700R4 (4L60). The 1993 Camaro, Corvette and Typhoon were equipped with the last production 700R4. The last design change of the 700R4 was an added checkball to the valve body. In 1992 electronic controls were added, and it became the 4L60-E . The 4L60E is not easily swapped with

2352-459: Is the THM350-C, which was phased out in 1984 in GM passenger cars for the 700R4. Chevrolet / GMC trucks and vans used the THM350-C until 1986. The lock-up torque converter was unpopular with transmission builders. 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)

2450-422: The 4L60 . 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). "60" is the relative torque value. For example, 80 is stronger than 60, which is stronger than 40, etc. A 4L80-E can handle more torque than a 4L60-E. The "E" denotes electronically controlled shifting. The 4L60 however

2548-527: The Chrysler Torqueflite 727 after 1979 until the FSJ platform was phased out. Additionally, the THM400 has been mated to other engines using adapter kits. THM400 transmissions are very popular in automotive competition due to their great strength. 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

2646-436: The 1930s, automakers sought to reduce or eliminate the need to shift gears. At the time, synchronized gear shifting was still a novelty (and confined to higher gears in most cases), and shifting a manual gearbox required more effort than most drivers cared to exert. The exception here was Cadillac's break-through synchromesh fully synchronized manual transmission, designed by Cadillac engineer Earl A. Thompson and introduced in

2744-524: The 1940 model year . The first Oldsmobiles so equipped were shipped in October 1939 in the Oldsmobile Series 60 and the Oldsmobile Series 70 . Oldsmobile was chosen to introduce the Hydra-Matic for two reasons: economies of scale —Oldsmobile produced more cars than Cadillac and Buick at the time, thus providing a better test base—and to protect the reputation of Cadillac and Buick in case of

2842-660: The 1964 model year under the name "Turbo Hydra-Matic" in Cadillacs and "Super Turbine" in Buicks. The following year, application expanded to Oldsmobile and Pontiac and to some full-sized Chevrolets. Many of the BOC (Buick, Oldsmobile, Cadillac) THM400s produced between 1964 and 1967 were equipped with a variable-pitch stator torque converter called " Switch-Pitch " (SP); these are sought after by collectors and drag racers. A SP THM400 always has an external 2 prong connector, whereas

2940-587: 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) — the Turbo-Hydramatic 200. The THM-200 was first used in 1976 models including GM's T-cars (which includes the rebadged Isuzu Gemini sold through Buick dealers as the Buick/Opel by Isuzu), X-cars , and some Isuzu automobiles (Chevrolet LUV and Isuzu P'up). However, this transmission

3038-667: 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. Also in the 1980 model year, the THM-200 received a lockup torque converter, and some internal components (primarily the low/reverse clutch drum and planetary gears) were later shared with

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3136-459: The 3-2 solenoid to a different style which makes it not interchangeable with any previous models. For the model year 1996 GM trucks, there were two versions of the 4L60E: one had a bolt-on bellhousing, the other did not. In total, there are nine different bolt-on bellhousings. The bolt-on bellhousings used on the 4.3 L V6 and 1996-2002 GEN I+ versions of the small-block Chevrolet V8 used the same bellhousing. These had one from 1996 to 1997 and then

3234-433: The 3L80s, but the current model has had a 4L80E since the mid-1990s. Through the end of the '70s substantially more CBOP (Cadillac/Buick/Oldsmobile/Pontiac) bellhousing THM400s were produced than any other THM400. Chevrolet bellhousing THM400s, while not rare, can be hard to find and are, as a result, usually more expensive to buy (they were commonly found in 3/4 ton (8500 GVW and above) Chevrolet/GMC trucks and vans (includes

3332-412: The 4L60, as the 4L60E depends on a powertrain control module (PCM) to shift. 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. In 2001, an updated version — the 4L65-E, was introduced. Five-pinion planetaries, along with a strength-improved output shaft, were improved to withstand the 300+ lb·ft (400+ N·m) of torque of

3430-482: The 6.0 Vortec engine. The 4L70E transmission is the same as a 4L65E with a speed sensor located in the pump. The Turbo Hydra-Matic 700R4 can be identified by a rectangular-shaped oil pan with 16 bolt holes. The tailshaft housing is held onto the main case by four bolts (the bolt spacing is similar to the THM350), and uses a square-cut o-ring seal, and not a gasket. The typical width of this transmission where it bolts to

3528-402: 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. 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. 4L60Es manufactured after 1995 use snap-in connections instead of threaded. The original version of

3626-560: The 700R4, most 200-4Rs have a multicase bellhousing for use with Chevrolet, Buick/Olds/Pontiac (BOP), and Cadillac engines. However, 200-4Rs share mounting locations with the TH-400. Since the external dimensions are longer than the TH-350 but the drive shaft yoke spline count/diameter was the same, the 200-4Rs can be swapped in place of TH-350s, with the shortening of the drive shaft, in older vehicles to provide an overdrive gear. Early models had

3724-644: 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 - which bolted to its inline six and V8. 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 until AMC/Jeep phased in

3822-541: The Nova and Camaro (1974 and 75 model year only). During the 1976 model year the THM250 was phased out of production, replaced with the lighter duty THM200. It was later reintroduced in 1979 as the THM250-C in the wake of the failure-prone THM200/200C - the later 250C was further lightened with the use of a sun gear shell used with the THM350 but with 3 holes to reduce rotating mass and the low/reverse piston with 8 cutouts. After

3920-559: The P-series box vans and 1983-86 CUCVs) when RPO M40 was checked off the option list - especially when coupled to a 454 - usually in HD applications including the C40-C60 medium duty trucks where a bolt-on output shaft is used in place of a slip yoke) - when used with passenger cars it was usually coupled to a Mark IV engine or some high performance small blocks (e.g. the 1970 LT-1). The THM400

4018-515: The S/T platform with the 2.8L, 3.5L and 4.2L engines (one used in 2002 and the other from 2003 and on). Hydramatic Hydramatic (also known as Hydra-Matic ) is an automatic transmission developed by both General Motors ' Cadillac and Oldsmobile divisions. Introduced in 1939 for the 1940 model year vehicles, the Hydramatic was the first mass-produced fully-automatic transmission developed for passenger automobile use. During

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4116-537: The SP). Vehicles originally equipped with the Switch Pitch ST300 can be identified by their "Park R N D L2 L1" gearshift selector. THM400 units had a 32 spline output shaft. A variant known as a THM375 is a THM400 built to mate to the smaller driveshaft yokes typically used for THM350 applications. They used a Chevrolet bolt-pattern case with a longer 27 spline output shaft inside a matching tailhousing cast with

4214-508: The Turbo-Hydramatic 200-4R. The low/reverse sprag (roller clutch) assembly was also shared with the 1988-04 Chrysler Torqueflite 904 (also 30, 31, 32RH) and its derivatives e.g. the A500 and 42RE. THM200/200Cs were produced until 1987. The 200-4R was introduced for the 1981 model year. Some components which were prone to failure in the THM200 were improved, and in the later 1980s, this transmission

4312-554: The autumn of 1928. Cadillac, under Thompson, began working on a 'shiftless' transmission in 1932, and a new department within Cadillac Engineering was created, headed by Thompson and including engineers Ernest Seaholm, Ed Cole , Owen Nacker , and Oliver Kelley. During 1934, the Cadillac transmission group had developed a step-ratio gearbox that would shift automatically under full torque. This same group of engineers

4410-409: The benefit of a converter clutch. Many Hydramatics did not execute the 2-3 shift very well, as the shift involved the simultaneous operation of two bands and two clutches. Accurate coordination of these components was difficult to achieve, even in new transmissions. As the transmission's seals and other elastomers aged, the hydraulic control characteristics changed and the 2-3 shift would either cause

4508-424: The corporation and the three divisions that used this transmission scrambling for other sources of automatic transmissions to complete that year's model year production. As a result, Oldsmobiles and Cadillacs during the downtime were assembled with Buick's Dynaflow transmission, while Pontiacs used Chevrolet 's Powerglide , both two-speed torque-converter units. Non-GM makes that bought Hydra-Matics from

4606-549: The corporation, including Ford Motor Co.'s Lincoln division and independent automakers Hudson, Kaiser, and Nash ended up looking for other sources of automatic transmissions as well, with Lincoln using the Borg-Warner-designed Ford-O-Matic transmission, while other automakers also switched to automatics from Borg-Warner during the downtime. About nine weeks after the Livonia fire, GM opened up

4704-437: The day. Controlled-Coupling Hydra-Matic was substantially smoother than the original Hydra-Matic , but also more complex and expensive to produce, just as efficient as the original HydraMatic because all HydraMatic transmissions, including Roto Hydra-Matic and Tempest Torque , use the split-torque design. In 1961, The model 375 Roto Hydramatic was produced. The Roto is a four range three speed unit. The Roto eliminated

4802-474: The early 1980s, the Turbo-Hydramatic was gradually supplanted by four-speed automatics, some of which continue to use the "Hydramatic" trade name. 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. The THM400 can be visually identified by an oil pan number four shown at General Motors Transmission Pans . First introduced for

4900-566: The end of production in 1982. By 1980, the relatively heavy THM400 was being phased out of usage in passenger cars in response to demand for improved fuel economy. 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. Today, the United States Army HMMWV is the only vehicle using the THM400. The civilian Hummer H1 originally had

4998-403: The end, the true Hydramatic was rendered obsolete because of its cost, both in raw materials used as well as the machining needed. The successor, Turbo Hydramatic , was a much simpler, lighter, and cheaper, if less efficient, transmission. Bell housing Bellhousing (aka bell-housing or bell ) is a colloquial term for the component that aligns and connects the transmission of

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5096-535: The engine is 20 in (51 cm) overall. From the engine/trans mating surface to the cross member mount bolt is 22.5 in (57 cm), and engine/trans surface to output shaft housing mating surface is 23.375 in (59.37 cm) overall, with the tail shaft housing typically measuring 7.625 in (193.7 mm). External dimensions are similar to a THM350 with a 9-inch tailhousing found in Chevrolet/GMC long wheelbase truck/vans and 1971-76 B-bodies (Bel Air, Impala, Caprice). Transmission fluid cooler lines on

5194-506: The engine output as a torque converter does. (In this way, it was less sophisticated than the 1924 Vulcan (Vulcan-Werke Hamburg und Stettin) prototype, which had a torque converter.) It incorporated a parking pawl which was engaged when the shift selector was placed in reverse with the engine off. There was no separate Park position as found with modern transmissions. The result, dubbed " Hydra-Matic Drive ", went into production in May 1939 for

5292-513: The engine was running, the band was applied by a combination of spring pressure assisted by oil pressure). With the engine off, this brake band acting on the rear unit ring gear had a tremendous mechanical advantage. Since the rear unit ring gear with its attached reverse unit sun gear and the reverse unit ring gear were both locked to the transmission case, the planet carriers and driveshaft could not turn. As such, it provided an effective driveshaft mounted parking brake to be used alone or supplementing

5390-469: The first Hydramatic to incorporate electronic controls — almost all of the THM400/3L80/3L80HD's components are interchangeable. Transmission fluid cooler line connections are found on the right-hand side of the THM400. The lower connection is the cooler feed, and the upper connection is the return. The case is tapped for either 1/4" National Pipe Straight NPS fittings,or 1/2" UNF fittings with

5488-400: The fluid coupling to the rear unit sun gear. The planet carrier of this gearset was splined to the planet carrier of the reverse unit. The rear unit ring gear hub had a small gear machined on its end which served as the reverse unit sun gear. Because the rear unit band was not applied for reverse, the rear unit and reverse unit compounded causing the combined planet carriers to rotate opposite to

5586-410: The forward gear assembly went back into reduction, and the rear gear assembly locked. Due to the manner in which the rear gear assembly was arranged, the coupling went from handling 100 percent of the engine torque to about 40 percent, with the balance being handled solely by the gear train. This greatly reduced slippage, which was audible by the substantial reduction that occurred in the engine RPM when

5684-593: The front fluid coupling that was used in the Controlled coupling Hydramatic and the connection between the engine and transmission was made by using the small fluid coupling that is used also to control the front planetary gear set' (in which the "dump and fill" shifting principle was retained from the older controlled coupling Hydramatic). The Roto was adopted for all Oldsmobiles as well as Pontiac's full-sized Catalina, Ventura, and Grand Prix models, while all Cadillacs and Pontiac's Bonneville and Star Chief models retained

5782-407: The gear train. 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). Since the first gear reactive force is evenly distributed around the periphery of the case,

5880-525: The geartrain; this difference in layout would have permitted the THM350 to be adapted to the Corvair where the drive and driven ends are the same, but 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 the Chevrolet Vega and Nova 6. One THM350 weak point was excessive end-play between

5978-483: The hand brake. The first-generation Hydramatic (not the Controlled-Coupling version that succeeded it in 1956) did not have a separate park position as found in modern automatic transmissions. The driver had to shut off the engine and then place the transmission in reverse in order to lock the driveline to prevent the car from moving. Also, the original Hydramatic required periodic band adjustments as

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6076-407: The input torque and at a further reduced speed. The output shaft was machined onto the rear unit and reverse unit planet carriers. Shutting off the engine caused the transmission oil pressure to rapidly dissipate. If the selector lever was in reverse or moved to reverse after the engine stopped, two mechanical parts combined to provide a parking brake. The reverse unit ring gear was held stationary by

6174-407: The lightweight matching splines in the case. This weakness can be addressed by using an inexpensive aftermarket case saver kit. Four-wheel drive truck applications for the THM350 used an iron adapter that mated it 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

6272-604: The need for a torque converter. Despite the name, the Turbo-Hydramatic has no mechanical or design related to the original Hydra-Matic , or the Controlled-Coupling Hydramatic. Hydra-Matic was a complex design that was expensive to produce. Despite some early problems, it was reliable and so rugged it was widely used in drag racing during the 1960s. It was not as smooth as some competitors' transmissions (notably Buick's Dynaflow ), but

6370-465: The oil pump housing, were updated, ending with the auxiliary valve body for 700s manufactured after October 1986. In 1995, the 4L60E received a PWM -controlled lockup converter. The early designs simple on or off lockup function while the later design can regulate the apply pressure as to not feel the lock up occur. GM added a fifth solenoid to the valve body, called the PWM solenoid. In 1996, GM introduced

6468-436: The older four-speed Controlled-Coupling Hydra-Matic unit. Controlled Coupling HydraMatic and Roto HydraMatic both have the "Split Torque feature" whereby, in high gear, the torque is divided 40% through the fluid coupling and 60% through mechanical connection, which made these transmissions more efficient than any other automatics before the lock-up torque converter was used. Hydramatic transmissions were ultimately replaced by

6566-487: The original Hydra-Matic were 3.82:1, 2.63:1, 1.45:1, and 1.00:1 in automotive applications, and 4.08:1, 2.63:1, 1.55:1, and 1.00:1 in light truck and other commercial applications. The Controlled-Coupling Hydra-Matic used 3.97:1, 2.55:1, 1.55:1, and 1.00:1. Roto Hydramatic 375 ; a three-speed, four-range automatic has a 3.56:1, 2.93:1, 1.56:1, and 1.00:1. Roto Hydramatic 240 ; a three-speed, four-range automatic has ratios of 3.64:1, 3.03:1, 1.57:1, and 1.00:1 The Hydramatic

6664-410: 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. 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. Another weak point is the relatively thin center support and

6762-424: The pump's displacement and therefore the volume of oil being delivered. The rear pump was an unregulated gear pump driven from the transmission output shaft, which meant it was capable of pressurizing the transmission if the vehicle was in motion. This feature made it possible to push-start a vehicle with a dead battery if the vehicle could be accelerated to at least 15–20 mph (24–32 km/h). At higher speeds,

6860-423: The pumps themselves were made of made up of steel segments like a power steering pump. There was a steel hub and variable ratio outer ring. Because the pump segments traveled in an eccentric circle, guide rings were necessary on top and bottom of the center hub. These rings would break and cause the pump to stop pumping, as well as damaging the aluminum housings. Aftermarket hardened rings solved this problem. Unlike

6958-407: The rear pump provided all the oil volume that was needed to operate the transmission and the front pump's slide was nearly centered, causing that pump to produce little output. In first gear, power flow was through the forward planetary gear assembly (either 1.45:1 or 1.55:1 reduction, depending on the model), then the fluid coupling , followed by the rear gear assembly (2.63:1 reduction) and through

7056-418: The reverse anchor. The driveshaft could still turn to cause the reverse unit sun gear and attached rear unit ring gear to rotate at a very high speed, were it not for the fact that the rear unit ring gear band was now applied by a heavy spring. Usually, bands are applied by a servo and released by spring pressure, but in this case, the band was held off by the servo and applied by spring pressure (actually, when

7154-409: The reverse gear assembly (normally locked) to the output shaft. That is, the input torus of the fluid coupling ran at a slower speed than the engine, due to the reduction of the forward gear assembly. This produced an exceptionally smooth startup because of the relatively large amount of slippage initially produced in the fluid coupling. This slippage quickly diminished as engine RPM increased. When

7252-418: The scale at a solid 435 pounds. When coupled to GMC's heavy V6 powerplant of 1960–1962, the powertrain weight was not too much lighter than the weight of the entire body of a ¾ ton P-2500 model pickup truck. Even its successor, the Controlled-Coupling Hydramatic was reviled by shop mechanics having to remove or reinstall such a unit, as they, too, were quite heavy when compared to other contemporary units. In

7350-437: The secondary coupling. It was a later version of GM's "dual-range Hydra-Matic", first introduced in some 1952 models. The dual range feature allowed the driver to hold the transmission in third gear until the maximum allowable upshift points, for improved performance in traffic or in mountain driving. The new, dual coupling transmission also incorporated a separate park position, falling in line with other automatic transmissions of

7448-399: The shift occurred. The shift from third to fourth gear locked the forward gear assembly, producing 1.00:1 transmission. The fluid coupling now only handled about 25 percent of the engine torque, reducing slippage to a negligible amount. The result was a remarkably efficient level of power transfer at highway speeds, something that torque converter equipped automatics could not achieve without

7546-511: The shift points and part throttle kickdown. This setup was later incorporated into the THM700R4. Because the THM-200 shared external dimensions and output shaft size and spline count with the THM-350, the THM-350 was often used to replace the weaker, less reliable THM-200 and THM-250C. The only thing which had to be added was a vacuum line to the vacuum modulator on the THM-350. Starting with

7644-456: The substantially redesigned Controlled-Coupling HydraMatic (also called Jetaway , by Oldsmobile, and StratoFlight , and later Super Hydra-Matic , by Pontiac, or 315 HydraMatic , by Cadillac, or Dual-coupling Hydra-Matic ) in 1956. The Controlled-Coupling Hydra-Matic incorporated a secondary fluid coupling and a pair of sprag clutch in place of the former friction clutch and brake bands, shifting in part by alternately draining and filling

7742-468: The transmission had a 27-spline input shaft (shared with the THM200C and 2004R) which was a common failure point. 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. Between 1984 and 1987, internal components, from the ring gear to

7840-480: The transmission housing, particularly with front wheel drive transmissions. An integral bell has a front bolt pattern that matches the engine to which it will be paired, and a divorced bell additionally has a rear bolt pattern that matches the gearbox to which it will be paired. The use of different bellhousings on a transmission allows the same transmission to be used on multiple engines in multiple applications. This article about an automotive part or component

7938-401: The transmission upshifted to second gear, the forward gear assembly locked and the input torus now ran at engine speed. This had the desirable effect of "tightening" the coupling and reducing slippage, but also produced a somewhat abrupt shift. It was not at all uncommon for the vehicle to lurch forward during the 1-2 shift, especially when the throttle was wide open. Upon shifting to third,

8036-559: The two forward gears. Oldsmobile offered the AST from 1937 to 1939, while Buick offered it only in 1938. The HydraMatic was designed to combine the hydraulic operation of a planetary gearbox (allowing much shifting to be automated) with a fluid coupling instead of a friction clutch, eliminating the need for de-clutching. The transmission would have four forward speeds (3.82:1, 2.63:1, 1.45:1, and 1.00:1) plus reverse, with all acceleration provided by gearing; its fluid coupling did not multiply

8134-428: The types of mechanical (and some times violent) failures that have plagued other competition transmissions are rare. The THM400 was the first three-speed, Simpson-geared automatic to use overrunning clutches for both first and second gear reaction, 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. Owing to this feature, as well as

8232-405: 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. As a result, it has met with considerable success in commercial vehicle applications. For 1987, GM changed the nomenclature of their Turbo Hydramatic transmissions — the THM400

8330-439: Was also regarded as a 'three speed Powerglide' and during its development, was generally called this. 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 and was largely derived from the Chevrolet design. An important difference in the THM350 compared to the THM400 is that there is no fixed center support midway through

8428-405: Was fitted with two pumps to pressurize its hydraulic control system and provide lubrication of internal components. The front pump was a variable displacement vane unit driven from the fluid coupling housing, which meant oil pressure would be available immediately upon starting the engine. Relatively constant pressure was maintained by moving a slide inside the pump, which had the effect of changing

8526-687: Was halted for wartime production in February 1942. During the war, the Hydramatic was used in a variety of military vehicles, including the M5 Stuart tank (where two of them were mated to twin Cadillac V8 engines) and the M24 Chaffee light tank. The extensive wartime service greatly improved the postwar engineering of the transmission, later advertised as "battle-tested". Starting in 1948 Hydramatic became optional for Pontiacs (and

8624-536: Was in 70% of them that year), although Buick and Chevrolet chose to develop their own automatic transmissions, called Dynaflow and Powerglide . All Oldsmobiles installed with the Hydramatic had at the bottom edge of the front fender directly behind the front wheel a badge that said "Futuramic" which identified an Oldsmobile approach to simplified driving, and the presence of an automatic transmission. V8 Oldsmobiles were automatic-only in 1949 as Oldsmobile lacked

8722-536: Was made standard in 1969. Cast-iron Hydra-Matic production ceased at Willow Run after the 1962 model year, and Controlled-Coupling Hydramatic ceased in early 1964, allowing retooling time for the Turbo Hydra-Matic 400, which debuted in the 1964 Cadillac models in mid-year, with Pontiac Division's Star Chief and Bonneville models being the last to use the Controlled-Coupling Hydramatic (Model HM315) of any GM car. 1964 Turbo-Hydramatic production used

8820-556: Was modified. The standard TH350 is still very popular in drag racing. The THM250 is a derivative of the THM350 and was introduced for 1974 in Chevrolets as a Powerglide replacement. Internally, the THM250 is a THM350 without the intermediate clutch pack and with a band adjuster similar to the Powerglide. The THM250 was usually coupled to smaller displacement engines - the largest a third generation Chevrolet inline six found in

8918-429: Was more efficient, especially at highway speeds. The Hydra-Matic paved the way for widespread acceptance of automatic shifting. A 3-speed light-duty version of the Turbo Hydra-Matic , called the Turbo-Hydramatic 180 was produced by GM's Hydra-Matic division from 1981 to 1998 for use in a wide variety of small cars and trucks. Hydramatic is a trade name for GM's automatic transmission division, which produces

9016-524: Was never produced with a multicase bell housing . Other auto manufacturers have used the THM400 and its 4L80E successor, 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

9114-642: Was notorious for its failure rate when used behind any engine - the largest being the Oldsmobile 5.7 L diesel. Multicase bellhousings were used - bellhousing patterns included Chevrolet V8, Buick-Oldsmobile-Pontiac, Vega 4 , GM 60 degree pattern (includes the Tech IV), and Isuzu G engine . It was GM's first transmission which used a throttle valve cable (similar in design to the Chrysler Torqueflite part throttle kickdown linkage) controlling

9212-402: Was renamed '3L80' (three forward speeds, longitudinal positioning, and an arbitrary strength rating of 80, the second highest such rating assigned). The 3L80HD was introduced in 1987 as the HD unit used in passenger trucks. 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

9310-453: Was subsequently replaced in that role by Chevrolet Division's Powerglide (where it was dubbed "Pow-R-Flow") in the GMC light truck line, and later, in 1966, with the Turbo Hydra-Matic (THM) in GMC light trucks, whose simplified design was much less costly to manufacture. Chevrolet Division's light truck line used the less-than-adequate Powerglide all through the 1960s until Turbo-Hydramatic

9408-494: Was the Truck Hydra-Matic version offered by GM Truck and Coach Division in its line of light- and medium-duty trucks and conventional buses, as well as with its transverse-mounted gas L6 engined transit buses produced until 1963. That particular version weighed in at an incredible 655 pounds when equipped with the angle drive for the transit bus application, while the ¾ ton and up pickup truck model (HM270) still tipped

9506-521: Was then moved into the General Motors Research Laboratory , building pilot transmission units during 1935–36 which were then handed to Oldsmobile for testing. The Automatic Safety Transmission (AST) was a tangent outgrowth of this work. The AST was a semi-automatic transmission using planetary gears and conventional friction clutch , requiring the driver to use the clutch to shift into or out of gear, but not between

9604-558: Was used with high-power applications — primarily the Buick Grand National and the 1989 Pontiac Firebird Trans Am Indy 500 Pace cars. The 200-4R was configured with several different torque converters depending on the vehicle application. However, this transmission was also prone to failure (especially in D-body Cadillacs) and received improvements during its production run. The first improvement came in 1984 with

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