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359:. The C in Turbo-Hydramatic 125 C denoted the use of a TCC. The solenoid that controls this is notorious for failure due to overheated plastic componentry, and problems indicated by an engine stall when stopping from speeds greater than 55 MPH. This occurs because the clutch does not disengage, and as the affected vehicle's speed nears zero miles per hour, the engine is forced to decelerate to zero rpm.
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The 440-T4 was originally slated to be used with downsized C-Body cars for 1984. However, issues with failures due to lack of fluid lubrication to critical clutch train parts in the relatively complex and compact design, led to the introduction of transverse FWD 4-speed automatics being delayed as an
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One unique feature of this transmission is its use of both a modulator valve and a throttle valve (TV) cable. Most transmissions either use one or the other to control shift points and shift smoothness. On the Turbo 440-T4, the TV cable exclusively controls the shift points, while the modulator
402:'s common sungear layout. This transaxle was first used in GM's 1985 Buick Park Avenue, Oldsmobile 98, and Cadillac Deville. In 1986, after switching to FWD, the Buick LeSabre, Oldsmobile Delta 88, and later, the Pontiac Bonneville also used this transaxle. The 440-T4 was later renamed the
410:, which incorporated upgraded final drive hardware but was otherwise mechanically indistinguishable from standard units, was used in the 1989-1990 Pontiac Grand Prix with the turbocharged engine. GM started adding electronic controls to the 4T60 in 1990 with the
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valve controls the shift feel, with very little overlap between the effects of one adjustment on the other. This feature makes it very easy for a do-it-yourself mechanic to adjust the transmission shift points with minimum effect on the shift feel.
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The TCC acts similar to a clutch in a manual transmission vehicle, in that at speeds above 35 MPH a combination of engine vacuum- and temperature-sensing valves, and a dedicated brake switch - and in later models an
375:. While a similar design was used for the later 4T65E, the three speed design was utilized for only three model years, after which all-wheel drive was discontinued as an option for the car line.
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which engaged a clutch physically locking the impeller and turbine inside the torque converter together causing engine power to be transferred directly to the
398:. Virtually no internal parts were shared with the 125, and overdrive was achieved by departing radically from the standard single Simpson compound
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For the 1988 model year, the
Pontiac Division of GM utilized a THM 125C modified to accommodate a full-time All-Wheel-Drive
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The model THM440T4 indicates Turbo HydraMatic Model 440, Transversely
Mounted, 4 Speed Fully Automatic transaxle.
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transfer case and output housing to send 40% of the output torque to the rear wheels in the 3.1 liter powered
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later, following GM's new naming convention. After the 1995 introduction of the electronically controlled
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was introduced in 1980 and produced through 2001. It carried over some parts from the light-duty
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A 4-speed transaxle which replaced the 125, was created for the 1985–1986
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A Hydra-Matic 3T40 transmission, produced between 1979 and 2001, at the
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application. Introduced in 1980, the line evolved into today's
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278:4-speed, the 3T40 was gradually phased out.
430:option until 1984 for the 1985 model year.
50:. Unsourced material may be challenged and
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114:Learn how and when to remove this message
418:, and 1991 and after with the corporate
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145:Ypsilanti Automotive Heritage Museum
48:adding citations to reliable sources
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524:General Motors transmissions
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234:was the first in a line of
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363:Turbo-Hydramatic 125 C AWD
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509:List of GM transmissions
396:Turbo-Hydramatic 440-T4
379:Turbo-Hydramatic 440-T4
340:torque converter clutch
236:automatic transmissions
334:Turbo-Hydramatic 125 C
190:automatic transmission
63:"Turbo-Hydramatic 125"
264:Turbo-Hydramatic 200
260:Turbo-Hydramatic 125
254:Turbo-Hydramatic 125
232:Turbo-Hydramatic 125
132:Turbo-Hydramatic 125
44:improve this article
392:GM H platform (FWD)
388:GM C platform (FWD)
483:Pontiac Grand Prix
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400:planetary gearset
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104:December 2009
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59:Find sources:
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29:This article
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485:(Turbo Only)
472:Buick Reatta
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42:Please help
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317:U-body vans
493:1987–1992
481:1989-1990
470:1988-1990
464:1988-1990
458:1984-1993
452:1985-1993
446:1986-1993
440:1988-1994
394:cars, the
206:Chronology
187:transverse
167:Production
74:newspapers
357:transaxle
211:Successor
170:1979–2001
31:does not
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503:See also
478:4T60-HD
353:solenoid
185:3-speed
152:Overview
408:4T60-HD
373:6000STE
323:engine)
196:Related
88:scholar
52:removed
37:sources
460:A-body
454:C-Body
448:H-Body
442:W-Body
420:4T60-E
319:(with
311:L body
305:W-body
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276:4T40-E
250:line.
223:4T80-E
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95:JSTOR
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344:TCC.
272:3T40
266:and
230:The
67:news
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