Overhaul - 3t40 Buick Century V

APPLICATION & LABOR TIMES

APPLICATION & LABOR TIMES

IDENTIFICATION

Transaxle identification plate is attached to transaxle case. (Scheme 1) Transaxle model is printed on the service parts identification label located inside vehicle trunk.

Scheme 1

DESCRIPTION

Automatic 3-speed transaxle consists of a torque converter, final drive gear, differential, 3 multiple clutch disc packs, roller clutch, intermediate band, valve body and oil pump. The 4-element torque converter couples the engine crankshaft to the planetary gear set through a sprocket and drive link assembly. (Scheme 2)

Scheme 2

LUBRICATION & ADJUSTMENTS

See appropriate AUTOMATIC TRANSMISSION SERVICING article in TRANSMISSION SERVICING.

1. For 1993 Vehicles, see «TRANSMISSION SERVICING - A/T»(ref-55695)
2. For 1994 Vehicles, see «TRANSMISSION SERVICING - A/T»(/buick/century/v-1982-1996/remont/automatic-trans/#servicing-at)

CONTROL VALVE BODY

See CONTROL VALVE BODY & OIL PUMP ASSEMBLY under TRANSAXLE DISASSEMBLY.

DRIVE AXLE SHAFTS

See FWD AXLE SHAFTS article in AXLE SHAFTS & TRANSFER CASES.

1. For 1993 Vehicles, see «AXLE SHAFTS - FRONT»(ref-42982)
2. For 1994 Vehicles, see «AXLE SHAFTS - FRONT»(/buick/century/v-1982-1996/remont/axle-shafts/#axle-shafts-front)

OIL COOLER FLUSHING

1. If flusher tool is available, fill line flusher with solution, and install Oil Cooler and Line Flusher (J-35944) to top transaxle cooler line on transaxle. Follow manufacturer's instructions to flush oil cooler and cooler lines.
2. If flusher tool is not available, flush cooler and cooler lines with a mixture of clean solvent and water. Flush cooler in both directions until all old fluid and debris are removed. If necessary, replace plugged or damaged cooler and/or lines.

TROUBLE SHOOTING

Note. For illustration of hydraulic circuit operation, see HYDRA-MATIC 3T40 article in OIL CIRCUIT DIAGRAMS.

Chatters Or Slips In 1st Gear

Check oil level, Throttle Valve (T.V.) cable, oil pressure, forward clutch, driven sprocket support and case cover gasket.

Inoperative Or Slips In 1st Gear

If vehicle is inoperative or transaxle slips in 1st gear, check for a leaking forward clutch piston seal. A new Viton Forward Clutch Piston Seal (8631986) is available to correct this condition.

Inoperative Or Slips In Reverse

Check for low line pressure. Check forward clutch, direct clutch, restricted low-reverse clutch housing cup plug, low-reverse pipe "O" ring, low-reverse clutch plates, case-to-cover gasket and direct clutch plates.

Delayed Or No Upshifts

Check manual linkage, Throttle Valve (T.V.) cable, oil level, governor, intermediate servo and band, control valve assembly, valve body spacer, case cover and case.

Slipping Or Rough 1-2 Shift

Check oil level, Throttle Valve (T.V.) cable, oil pressure, intermediate servo and band, T.V. link, control valve assembly, 1-2 accumulator piston and seal, spacer plate, case and case cover.

Delayed Or Rough 2-3 Shift

Check oil level, T.V. valve, manual linkage, oil pressure, direct clutch, direct clutch exhaust No. 1 check ball and control valve assembly.

Slipping, Soft Or Early 2-3 Shift

Check oil level, Throttle Valve (T.V.) cable, manual linkage, oil pressure, intermediate servo, accumulator exhaust check valve, spacer plate, check ball No. 5, case cover and direct clutch.

Delayed Or No 2-3 Shift

Check oil level, T.V. valve or manual linkage, governor, speed sensor, intermediate servo, accumulator exhaust check valve, direct clutch accumulator cup plug, case-to-governor shaft sleeve, center gasket, case cover, throttle lever and bracket assembly, control valve assembly, spacer plate, case-to-governor shaft sleeve and direct clutch.

Delayed Neutral-To-Drive Shift

Check for lack of oil feed to forward clutch.

Delays In Drive & Reverse

Check oil level, oil pressure, converter-driven sprocket support bushings and turbine shaft. Some vehicles may have a delayed reverse-to-drive shift during cold weather operation. This condition may be caused by the manual valve and thermal element. Revised manual valve and thermal element use larger cross-drilled holes through the manual valve, and a second cold window has been added to the thermal element.

No 2nd Gear In "D"

Check low roller clutch for galled or missing rollers and missing springs.

All Gears Inoperative

Check oil level and pressure, drive link, manual linkage, input shaft, reaction carrier, differential and torque converter.

This condition may also be caused by the thermal element moving forward, because a retaining clip has fallen out. The clip may be located in the bottom oil pan.

Inoperative In "D"

Check oil level and pressure. Check forward clutch and case cover for leaks or incorrect gaskets between case cover and driven sprocket support passages.

Forward Gears Inoperative

Check oil pressure, manual linkage, driven sprocket support for turned sleeve, case cover, forward clutch and control valve assembly.

Transaxle Starts In 2nd Gear

Check governor and control valve assembly for a stuck 1-2 shift. Check throttle valve for sticking.

Transaxle Skips 2nd Gear

Check intermediate servo and band, accumulator exhaust valve and control valve assembly. Check spacer plate gaskets, case cover and case, governor feed to 1-2 shift valve, intermediate band apply feed orifice and spacer plate.

A no-2nd gear condition may be the result of fluid leaking past the intermediate servo piston. This may be caused by a worn inner servo piston lip seal. Check lip seal, intermediate band and direct clutch assembly for wear. Replace components as necessary.

Shifts From 3rd To 1st At High Speeds

Check governor or speed sensor, intermediate servo, direct clutch orifice No. 2 check ball and 1-2 accumulator.

No Full Throttle Detent Downshift

Check Throttle Valve (T.V.) cable, throttle cable assembly, control valve assembly and spacer plate.

No Overrun Braking In "1", Reverse Okay

Check manual linkage, low-reverse clutch and control valve assembly.

Binds In 3rd Gear

Check for damaged direct clutch center seal.

Inoperative In "2"

Check intermediate servo and band. Check 1-2 accumulator.

Engine Stalls In "R" Or "D"

Check for missing or clogged Torque Converter Clutch (TCC) auxiliary valve body filter. Also check for TCC engaging too soon. Fault may result from TCC wiring harness contacting valve body cover of transaxle. To correct this condition, repair any damaged wiring, and tape TCC wiring harness to larger main wire conduit.

Noise In All Gears

Check torque converter.

High Pitched Whine or Popping

Check oil pump system for pump cavitation or out-of-position filter.

Buzzing Or High Pitched Rattle

Check for binding, pinching or touching cooler lines (near radiator). Some vehicles may exhibit buzzing noise during slight throttle in forward gears: 2.3L "N" Body, and 3.1L "J" and "L" Bodies. This noise may be caused by vibration of the 1-2 accumulator valve. Revised spacer plates with smaller 1-2 accumulator orifice are now available to correct this problem.

Whine Or Growl Under Light Accessories

Check drive link assembly, sprockets, chain and related bearings.

Noise In 1st Or Reverse Gear

Check input gear, input internal gear, input carrier or input sun gear for damage.

Noise In 2nd Gear

Check for worn or pitted reaction gear set, reaction internal gear, reaction carrier, reaction sun gear, or related bearings and thrust washers.

Hum During Light Acceleration (All Gears)

Check differential or final drive gear and related parts for wear or damage.

Light Rattle In 2nd Or 3rd At 25-40 MPH

Check for warped steel plates, excess clutch pack clearance or parallel-grooved fiber plates in low-reverse clutch pack. Also check case for excess case-to-plate spline clearance.

TESTING

Note. Ensure engine is at normal operating temperature. Engine coolant temperature must be greater than 130°F (54°C) before Torque Converter Clutch (TCC) will engage. If temperature is not as specified, check and repair cooling system as necessary. If TCC will not engage, see TCC TESTING .

ROAD TEST

1. Shift gear selector to each shift position. Ensure shifts are immediate and not harsh. With gear selector in "D" position, accelerate vehicle using increasing throttle pressure. Note shift speed gear engagements for 2nd and 3rd gear. Also note shift speed for TCC engagement. TCC should engage at 23-42 MPH.
2. At vehicle speeds of 25-55 MPH, TCC should disengage and transaxle should downshift to 2nd gear when accelerator is depressed to half throttle or wide open throttle.
3. At vehicle speeds of 25-55 MPH, release accelerator while moving gear selector to "2" position. TCC should disengage, transaxle should downshift to 2nd gear and engine braking should occur.
4. Move gear selector to "D" position and accelerate vehicle to 25 MPH. Release accelerator while moving gear selector to "1" position. TCC should disengage, transaxle should downshift to 1st gear and engine braking should occur. Shifting points should agree with those listed in chart. (Scheme 3)
5. If shift points do not agree with chart, check ATF level, Throttle Valve (T.V.) cable adjustment and manual control linkages. See appropriate AUTO TRANS SERVICING article in TRANSMISSION SERVICING. See menu below. Ensure engine is tuned properly. If fluid level, cable adjustment and control linkages are okay, check line pressure. See «LINE PRESSURE TESTS»(/buick/century/v-1982-1996/remont/automatic-trans/#overhaul-3t40__line-pressure-tests). For 1993 Vehicles, see «TRANSMISSION SERVICING - A/T»(ref-55695) For 1994 Vehicles, see «TRANSMISSION SERVICING - A/T»(/buick/century/v-1982-1996/remont/automatic-trans/#servicing-at)

Scheme 3

Manual 2nd

With vehicle stopped, place gear selector in "2" position. Accelerate vehicle, and note 1st-2nd gearshift point. (Scheme 3) Accelerate vehicle to 25 MPH, and ensure 2nd-3rd gearshift does not occur and TCC does not engage.

Manual 1st

With vehicle stopped, place gear selector in "1" position. Accelerate vehicle to 15 MPH, and ensure no upshift occurs and TCC does not engage.

Reverse

With vehicle stopped, place gear selector in "R" position, and slowly accelerate to check Reverse gear operation.

LINE PRESSURE TESTS

1. Check ATF level, Throttle Valve (T.V.) cable adjustment and manual control linkages. See appropriate AUTOMATIC TRANSMISSION SERVICING article in TRANSMISSION SERVICING. Ensure engine is tuned properly.
2. Connect tachometer to engine. Connect pressure gauge to pressure test port on transaxle case. Pressure test port is on bellhousing side, above valve body cover.
3. Line pressure is controlled by pump output and pressure regulator valve. Line pressure is boosted by reverse boost valve in "R", "2" and "1" positions. Line pressure should increase with throttle opening in "N", "D" and "R" positions.

Minimum Throttle Valve (T.V.) Pressure Check

Ensure T.V. cable is properly adjusted. See appropriate AUTO TRANS SERVICING article in TRANSMISSION SERVICING. See menu below. Check line pressure with transaxle and engine speed in the indicated gears and RPM, respectively. (Scheme 4)

1. For 1993 Vehicles, see «TRANSMISSION SERVICING - A/T»(ref-55695)
2. For 1994 Vehicles, see «TRANSMISSION SERVICING - A/T»(/buick/century/v-1982-1996/remont/automatic-trans/#servicing-at)

Maximum Throttle Valve (T.V.) Pressure Check

With T.V. cable supported at full extent of travel, check line pressure with transaxle and engine speed in the indicated gears and RPM, respectively. (Scheme 4)

Scheme 4

Line Pressure Too Low

1. Check fluid level. Check oil strainer "O" ring seal for leakage or damage. Check for plugged oil strainer. If pressure is low in "N" and "D" positions, and low to normal in "2" and "R" positions, Throttle Valve (T.V.) cable may be out of adjustment or bound.
2. Inspect control valve and pump assembly for loose bolts or internal leaks. Check T.V. valve and plunger, shift T.V. valve, pressure regulator valve, T.V. boost valve and pressure relief valve for sticking or damage. Check for missing or misplaced No. 5 or 6 check ball.
3. Check 1-2 accumulator piston and/or seal. If pressure is low in "1" position only, check for damaged low blow-off valve and missing or misplaced No. 4 check ball. If pressure is low in "R" position only, inspect low-reverse clutch housing-to-case cup plug for leaks.
4. Inspect oil pump for loose bolts and damaged or missing pump valve seals. Check intermediate oil passages to pressure regulator for blockage. Check driven sprocket support-to-case cover for leaks.

Line Pressure Too High

1. With pressure high in "N" and "D" positions, and normal to high in "2" and "R" positions, check for broken, sticking or misadjusted Throttle Valve (T.V.) cable.
2. Inspect T.V. linkage for binding or incorrect cable. Check throttle valve or shift T.V. valve for sticking. Inspect T.V. lifter for bend or damage. Check if lifter length is too short.
3. Inspect components of control valve and pump assembly for sticking or damaged T.V. valve and plunger, shift T.V. valve, pressure regulator valve, T.V. boost valve and/or pump slide.
4. Check for worn or missing pressure regulator valve retaining pin. If line pressure is too high in "1" position only, check low blow-off valve for sticking. Inspect internal pump case or case cover for leaks.

CLUTCH & BAND APPLICATION CHART

CLUTCH & BAND APPLICATION CHART (1)

TORQUE CONVERTER

Note. Torque converter is a sealed unit and CANNOT be disassembled.

In-Vehicle Test

Install a tachometer, and warm engine to normal operation temperature. With vehicle in 3rd gear and speed between 50-55 MPH, converter clutch should engage. Engine speed should drop 200 RPM when clutch is engaged.

Bench Test

1. With converter removed from vehicle, insert fingers into splined inner race of roller clutch, and ensure stator turns freely clockwise, but does not turn or is very difficult to turn counterclockwise. DO NOT use driven sprocket support or shafts to turn race, as result may not be correct.
2. Using Torque Converter End Play Checker (J-35138), measure torque converter end play. (Scheme 5) End play for 245-mm torque converter is 0-.020" (0-.5 mm). End play for 298-mm torque converter is 0-.024" (0-.6 mm). Converter must be replaced if it leaks, is imbalanced or is contaminated with antifreeze.
3. Check torque converter bushing-to-stator support clearance by cutting a narrow strip of paper about.003" (.07 mm) thick. Lay paper against the inside diameter of torque converter bushing. Install stator support into torque converter. No clearance should be present.

Scheme 5

TORQUE CONVERTER CLUTCH (TCC) CONTROL COMPONENTS

Note. PCM may also be referred to as ECM.

The following components are used in TCC system. Not all components will be present on all vehicles.

Brake Switch

Power from ignition switch passes through brake switch to TCC solenoid. When brake pedal is depressed with TCC engaged, power to TCC solenoid is interrupted, releasing converter clutch and preventing engine from stalling.

Coolant Temperature Sensor

This sensor provides PCM with engine coolant temperature information. PCM will not allow TCC operation until signal from this sensor indicates coolant temperature greater than 130-150°F (55-65°C).

Powertrain Control Module (PCM)

To determine application of torque converter clutch, PCM receives and processes information from various input devices. These devices may include the vehicle speed sensor, coolant temperature sensor, throttle position sensor, 3rd and 4th gear switches and brake switch. The PCM controls application of torque converter clutch by providing a ground circuit for the TCC solenoid circuit.

TCC Solenoid Assembly

Solenoid is energized by PCM to redirect transmission fluid to the converter clutch apply valve in the auxiliary control valve assembly.

TCC Pulse-Width Modulated Solenoid

Acts with TCC regulator valve to control the apply and release of TCC.

Throttle Position Sensor (TPS)

Provides PCM with throttle position information. TCC operation is prevented when throttle position signal is less than a specified value.

Vacuum Sensor

Sends engine vacuum (load) information to PCM.

Vehicle Speed Sensor (VSS)

This sensor sends vehicle speed information to PCM. Vehicle speed must be greater than a certain value before TCC can be applied. Two types of speed sensor are used. A light emitting diode type is used in the instrument cluster on some models. Other models use a Permanent Magnet (PM) generator mounted in the transmission.

3rd & 4th Gear Switches

When open, 3rd and 4th gear switches prevent TCC operation. Switch status may be monitored by PCM, or switch may be an integral portion (series circuit) of TCC solenoid power supply.

Note. Diagnostic codes for coolant temperature sensor, throttle position sensor or vehicle speed sensor may be present while performing TCC electrical diagnosis. See ENGINE PERFORMANCE section for complete information on General Motors Computerized Engine Control systems.

TCC TESTING

Note. When diagnosing converter clutch problems, ensure engine and vacuum systems are operating properly.

Converter Clutch Solenoid

Disconnect harness connector to Torque Converter Clutch (TCC) solenoid. Measure resistance between TCC solenoid terminals "A" and "D". Solenoid resistance should be greater than 20 ohms. (Scheme 6)to 18.

Note. Some solenoids have an internal pressure switch in series with the solenoid winding and will not show continuity until that pressure switch is applied by transmission hydraulic pressure.

Converter Lock-Up Signal At Transmission

1. Warm engine to operating temperature. Raise vehicle and support drive wheels. Support suspension where necessary to prevent damage to drive axles.
2. Disconnect converter clutch connector at transmission. Connect a test light across terminals "A" and "D" of converter clutch harness. Start engine and place transmission in Drive. Accelerate vehicle to 45 MPH and note test light.
3. If test light is not on, check solenoid power supply wire of harness for open or short to ground. Check ground circuit for open between harness connector and PCM. If harness is okay, see CONVERTER LOCK-UP SIGNAL FROM PCM.

Converter Lock-Up Signal From PCM

1. Warm engine to operating temperature. Raise vehicle and support drive wheels. Support suspension where necessary to prevent damage to drive axles.
2. Connect a test light to battery voltage. Touch TCC control driver terminal with test light. On some vehicles, this is terminal "F" of the ALDL connector. (Scheme 6)-16. Accelerate vehicle to 45 MPH and note test light. If test light does not illuminate, problem is a faulty PCM connector or PCM.

Note. In the following schematics, Assembly Line Data Link (ALDL) connector is also referred to by manufacturer as Data Link Connector (DLC).

Scheme 6

Scheme 7

Scheme 8

Scheme 9

Scheme 10

Scheme 11

Scheme 12

Scheme 13

Scheme 14

Scheme 15

Scheme 16

Scheme 17

Scheme 18

REMOVAL & INSTALLATION

See appropriate AUTOMATIC TRANSMISSION REMOVAL article in TRANSMISSION SERVICING. See menu below.

1. 1993 Achieva, see «TRANSMISSION REMOVAL & INSTALLATION - A/T»(ref-56069)
2. 1994 Achieva, see «TRANSMISSION REMOVAL & INSTALLATION - A/T»(ref-56086)
3. 1993 Beretta, see «TRANSMISSION REMOVAL & INSTALLATION - A/T»(ref-56057)
4. 1994 Beretta, see «TRANSMISSION REMOVAL & INSTALLATION - A/T»(ref-56087)
5. 1993 Cavalier, see «TRANSMISSION REMOVAL & INSTALLATION - A/T»(ref-56068)
6. 1994 Cavalier, see «TRANSMISSION REMOVAL & INSTALLATION - A/T»(ref-56085)
7. 1993 Century, see «TRANSMISSION REMOVAL & INSTALLATION - A/T»(ref-56066)
8. 1994 Century, see «TRANSMISSION REMOVAL & INSTALLATION - A/T»(/buick/century/v-1982-1996/remont/automatic-trans/#removal-installation-at)
9. 1993 Corsica, see «TRANSMISSION REMOVAL & INSTALLATION - A/T»(ref-56057)
10. 1994 Corsica, see «TRANSMISSION REMOVAL & INSTALLATION - A/T»(ref-56087)
11. 1993 Cutlass Ciera, «TRANSMISSION REMOVAL & INSTALLATION - A/T»(ref-56066)
12. 1994 Cutlass Ciera, «TRANSMISSION REMOVAL & INSTALLATION - A/T»(/buick/century/v-1982-1996/remont/automatic-trans/#removal-installation-at)
13. 1993 Cutlass Cruiser «TRANSMISSION REMOVAL & INSTALLATION - A/T»(ref-56066)
14. 1994 Cutlass Cruiser «TRANSMISSION REMOVAL & INSTALLATION - A/T»(/buick/century/v-1982-1996/remont/automatic-trans/#removal-installation-at)
15. Cutlass Supreme, see TRANSMISSION REMOVAL
16. 1993 Grand Am, see «TRANSMISSION REMOVAL & INSTALLATION - A/T»(ref-56069)
17. 1994 Grand Am, see «TRANSMISSION REMOVAL & INSTALLATION - A/T»(ref-56086)
18. Grand Prix, see TRANSMISSION REMOVAL
19. 1993 LeMans, see «TRANSMISSION REMOVAL & INSTALLATION - A/T»(ref-56078)
20. 1993 Lumina, see «TRANSMISSION REMOVAL & INSTALLATION - A/T»(ref-56091)
21. 1994 Lumina, see TRANSMISSION REMOVAL
22. 1993 Lumina APV, see «TRANSMISSION REMOVAL & INSTALLATION - A/T»(ref-56091)
23. 1994 Lumina APV, see TRANSMISSION REMOVAL
24. Silhouette, see «TRANSMISSION REMOVAL & INSTALLATION - A/T»(ref-56091)
25. 1993 Skylark, see «TRANSMISSION REMOVAL & INSTALLATION - A/T»(ref-56069)
26. 1994 Skylark, see «TRANSMISSION REMOVAL & INSTALLATION - A/T»(ref-56086)
27. 1993 Sunbird, see «TRANSMISSION REMOVAL & INSTALLATION - A/T»(ref-56068)
28. 1994 Sunbird, see «TRANSMISSION REMOVAL & INSTALLATION - A/T»(ref-56085)
29. 1993 Trans Sport, «TRANSMISSION REMOVAL & INSTALLATION - A/T»(ref-56091)
30. 1994 Trans Sport, «TRANSMISSION REMOVAL & INSTALLATION - A/T»(ref-56091)

TRANSAXLE DISASSEMBLY

Clean exterior of transaxle case. Clean parts with solvent and dry with compressed air. Never use rags to dry parts. Remove torque converter by pulling straight out. Place transaxle in Holding Fixture (J-28664) and Bench Base (J-3289-20) so right axle end is down to drain fluid.

Internal Transaxle Speed Sensor (ITSS)

Remove speed sensor housing bolts, speed sensor housing and oil seal. Remove thrust bearing, speed sensor rotor and governor assembly. (Scheme 47)

Speedometer Drive Gear

Remove speedometer driven gear mount bolt with retainer. Withdraw speedometer driven gear assembly from governor cover. Remove governor cover bolts, cover and "O" ring. Lift out unit as an assembly. (Scheme 46)

INTERMEDIATE SERVO ASSEMBLY

1. Remove all, except 2, oil pan bolts. Leave these 2 bolts finger tight. Tap oil pan loose with rubber mallet. Remove oil pan and oil strainer. Discard oil strainer "O" ring. NOTE: DO NOT remove servo piston oil seals unless servo piston is to be replaced.
2. Remove reverse oil pipe retaining bracket-to-servo cover bolt. Remove remaining servo cover bolts. Lift off intermediate servo cover and gasket. Remove intermediate servo assembly. (Scheme 19)
3. If necessary, detach snap ring, and remove intermediate band apply pin from intermediate servo piston. Discard oil seals. Remove 3rd accumulator exhaust valve and spring. (Scheme 19) Inspect spring and exhaust valve for wear or damage. (Scheme 20)

Scheme 19

Scheme 20

Note. Perform BAND APPLY PIN SELECTION CHECK to determine correct pin to be used during reassembly.

Band Apply Pin Selection Check

1. Install Band Apply Pin Gauge (J-28535) over intermediate servo bore, and retain it with 2 servo cover bolts. (Scheme 21) Remove band apply pin from intermediate servo assembly.
2. Install Band Apply Pin Gauge Extension (J-28535-4) onto servo piston end of band apply pin. Install band apply pin and gauge extension into gauge on servo bore.
3. Using an INCH lb. torque wrench, apply torque of 100 INCH lbs. (11.3 N.m) to hex nut on gauge tool. If pin is correct size, White line on gauge extension will appear in window.
4. If White line does not appear in window, use a longer or shorter pin as necessary. See «INTERMEDIATE BAND APPLY PIN»(/buick/century/v-1982-1996/remont/automatic-trans/#overhaul-3t40) table. Repeat step 3) to ensure pin size is correct. Set selected pin aside until transaxle reassembly procedure.

INTERMEDIATE BAND APPLY PIN

Scheme 21

OUTPUT SHAFT & LOW-REVERSE SEAL

1. Detach low-reverse oil pipe, oil pipe seal back-up washer and "O" ring seal. Grind about 3/4" from end of a No. 4 screw extractor. Insert modified screw extractor into low-reverse cup plug. (Scheme 22) DO NOT hammer or force screw extractor into cup plug. Carefully twist screw extractor to remove cup plug.
2. Remove dipstick stop and parking lock bracket from above parking pawl and parking pawl actuator rod. Rotate final drive unit until open ends of output shaft retaining "C" ring are visible.
3. Using output shaft "C" Ring Remover (J-34757), push both ends of retaining "C" ring down to partially dislodge from output shaft. Rotate output shaft/final drive until "C" ring is visible. Carefully remove "C" ring with needle-nose pliers. Remove output shaft.

Scheme 22

CONTROL VALVE BODY & OIL PUMP ASSEMBLY

1. Remove all control valve cover bolts except 2. Leave these 2 bolts finger tight. Tap cover edge with rubber mallet to loosen control valve cover and gasket. DO NOT pry on cover during removal. NOTE: DO NOT remove lower left bolt marked "A" from control valve and pump assembly unless auxiliary valve body removal is necessary. (Scheme 23)
2. Remove 2 bolts securing throttle lever and bracket assembly to control valve. Lift off throttle lever and bracket assembly with throttle valve cable link. Use care not to bend link.
3. Remove all auxiliary valve body bolts except lower left bolt. (Scheme 23) Remove remaining control valve assembly bolts. Carefully lift off control valve and pump assembly. Place assembly on bench with machined surface up.
4. Remove No. 1 check ball from direct clutch passage on spacer plate. Lift out oil pump drive shaft. Remove spacer plate and spacer plate gaskets. Remove 5 check balls from case cover. (Scheme 24)

Scheme 23

Scheme 24

Input Shaft-To-Case Cover End Play

1. Install Output Shaft Loader Adapter Plug (J-26958-10) into right axle end. (Scheme 25) Mount Output Shaft Aligner/Loader (J-26958) and Bracket (J-26958-11) to right axle end of case. Adjust loader by turning handle until knob bottoms.
2. Install Input Shaft Lifter (J-28544) into input shaft bore and tighten. Install dial indicator with Extension Post (J-25025-7). Place indicator plunger on end of lifter. Press down on lifter, zero dial indicator, and lift up tool. End play should be.004-.033" (.10-.84 mm). End play snap ring is located on input shaft, beneath driven sprocket. If end play is not as specified, replace snap ring. See «INPUT SHAFT END PLAY SELECTIVE SNAP RINGS»(/buick/century/v-1982-1996/remont/automatic-trans/#overhaul-3t40) table.

INPUT SHAFT END PLAY SELECTIVE SNAP RINGS

Scheme 25

Scheme 26

1. Disconnect manual valve rod from manual valve. Remove remaining transmission case cover mount bolts. Install 2 bolts (12 x 1.75 x 50 mm) into case cover dowel pin holes. (Scheme 26)
2. Bolts will bottom out on dowel pins and separate case cover from case. DO NOT pry cover from case. Remove case cover, and lay side with 1-2 accumulator up, as 1-2 accumulator pin may drop out of cover.
3. Remove 1-2 accumulator spring, piston and center case-to-cover gasket. Remove case cover-to-drive sprocket thrust washer and driven sprocket thrust bearing assembly. Case cover-to-drive sprocket thrust washer may come off with case cover.
4. Remove and discard turbine shaft "O" ring. Remove drive sprocket, driven sprocket and chain as an assembly. (Scheme 2) Remove drive and driven sprocket-to-support thrust washers. These washers may come off with sprockets.
5. Using 3/16" drift, remove detent lever-to-manual shaft pin. Remove manual shaft-to-case nail. (Scheme 25) Withdraw manual shaft from case, and lift out manual valve rod and detent lever assembly. Remove park lock actuator rod.
6. Remove driven sprocket support and thrust washer on direct clutch side. (Scheme 27) Thrust washer may come out with driven sprocket support. Remove intermediate band anchor hole plug and intermediate band assembly.
7. While lifting input shaft, remove and separate direct and forward clutch assemblies. Remove input internal gear-to-input shaft thrust washer, and remove input internal gear.
8. Remove input carrier assembly, input carrier-to-input internal gear thrust washer and input carrier-to-input sun gear thrust washer. Remove input sun gear and input drum.

Scheme 27

REACTION UNIT

Note. Before disassembling reaction unit, measure reaction sun gear-to-input drum snap ring and low-reverse clutch housing-to-low race end play. This will determine appropriate snap ring and thrust washer to be used during transaxle reassembly procedure. See REACTION SUN GEAR-TO-INPUT DRUM END PLAY and LOW-REVERSE CLUTCH HOUSING-TO-LOW ROLLER CLUTCH RACE THRUST WASHER END PLAY.

Reaction Sun Gear-To-Input Drum End Play

1. Install Output Shaft Aligner/Loader (J-26958) in fully loaded position. (Scheme 23) Using 2 case cover bolts, install Reaction Sun Gear Snap Ring Gauge (J-28588) to case. (Scheme 26) Position gauge extension between open ends of selective snap ring.
2. Press reaction sun gear down to seat. Position gauge extension between open ends of snap ring. Install dial indicator onto Extension Post (J-25025-7). Position feeler gauge beneath shoulder of gauge extension, and zero dial indicator.
3. Rotate selective snap ring under gauge extension. Remove gauge from under shoulder. Dial indicator should indicate.005-.013" (.13-.33 mm) end play. If end play is not as specified, replace snap ring to adjust end play. Snap ring is located on reaction sun gear shaft. Measure thickness of snap ring for proper identification. See «REACTION SUN GEAR-TO-INPUT DRUM SNAP RING»(/buick/century/v-1982-1996/remont/automatic-trans/#overhaul-3t40) table.

REACTION SUN GEAR-TO-INPUT DRUM SNAP RING

Low-Reverse Clutch Housing-To-Low Roller Clutch Race Thrust Washer End Play

1. With dial indicator, gauge and output shaft aligner/loader still installed from previous procedure (REACTION SUN GEAR-TO-INPUT DRUM END PLAY), press down reaction sun gear to seat and zero dial indicator.
2. Insert screwdriver through parking pawl case opening. (Scheme 28) Lift reaction internal gear, and read low-reverse clutch selective end play. DO NOT rest screwdriver on spacer in parking pawl case opening, as spacer damage will result.
3. End play should be.003-.046" (.08-1.17 mm). Select appropriate washer to correct end play if necessary. See LOW-REVERSE CLUTCH HOUSING-TO-LOW ROLLER WASHER table. Washer controlling end play is located between low-reverse clutch housing and low roller clutch assembly.

Scheme 28

LOW-REVERSE CLUTCH HOUSING-TO-LOW ROLLER WASHER

Reaction Unit Disassembly

1. Remove dial indicator, gauge and output shaft aligner/loader. Leave output shaft loader adapter in place. Remove reaction sun gear. Remove low-reverse clutch housing-to-case snap ring. Snap ring is.092" (2.34 mm) thick. Using Low-Reverse Clutch Housing Remover/Installer (J-28542 or J-34008), remove low-reverse clutch housing. (Scheme 29)
2. Remove low-reverse clutch housing-to-case spacer ring from groove in case. Lift out final drive sun gear shaft and reaction gear set as an assembly. Remove roller clutch and reaction carrier assembly from final drive sun gear shaft.

Scheme 29

FINAL DRIVE UNIT

Note. Before disassembling unit, check final drive-to-case end play. This will determine the appropriate final drive differential-to-case thrust washer to be used during transaxle reassembly procedure. See FINAL DRIVE-TO-CASE END PLAY.

Final Drive-To-Case End Play

1. Position transaxle so right axle is up. Using Output Shaft Aligner/Loader Adapter Plug (J-26958-10), press down adapter to seat final drive onto final drive internal gear-to-case snap ring.
2. Install dial indicator onto post, and install post in motor mount bolt hole. (Scheme 29) Ensure indicator plunger rests on top of adapter. Zero dial indicator while pressing down on adapter.
3. Insert large screwdriver into transaxle governor bore, and lift final drive by prying up on governor drive gear. Dial indicator should indicate.005-.032" (.12-.81 mm) end play.
4. Select appropriate thrust washer to correct end play if necessary. See «FINAL DRIVE-TO-CASE THRUST WASHER»(/buick/century/v-1982-1996/remont/automatic-trans/#overhaul-3t40) table. Thrust washer controlling end play is located between differential carrier and differential carrier case thrust bearing assembly.

FINAL DRIVE-TO-CASE THRUST WASHER

Final Drive Unit Disassembly

1. Remove dial indicator, indicator post and loader/aligner adapter. Remove final drive internal gear spacer-to-case snap ring. Snap ring is .092" (2.34 mm) thick. Remove final drive internal gear spacer. Use care not to deform or bend spacer.
2. Using Final Drive Unit Remover/Installer (J-33381), lift final drive unit from case. Remove final drive differential-to-case selective thrust washer. Remove differential carrier-to-case thrust roller bearing assembly from final drive assembly. If thrust washer and thrust bearing did not come out with final drive assembly, remove from case.

COMPONENT DISASSEMBLY & REASSEMBLY

Note. Some procedures in COMPONENT DISASSEMBLY & REASSEMBLY may provide instructions for installing component(s) in transaxle case.

TRANSAXLE CASE

Note. Disassembly procedures provide instructions for removing drive sprocket roller bearing, drive sprocket support, 3rd oil cup plug, parking pawl and governor oil pipe. DO NOT remove components unless necessary.

Disassembly

1. Using slide hammer and Adapter (J-26941), remove driven sprocket support bearing. (Scheme 2)or (Scheme 47). Inspect bearing bore and roller bearing race on driven sprocket for wear or damage and replace if necessary.
2. To remove drive sprocket support, remove converter oil seal. Remove Torx bolts, and remove drive sprocket support. Using a screw extractor, remove parking pawl shaft cup plug from oil pan side of case. Remove parking pawl components as necessary.
3. To remove governor pipe, remove governor oil pipe clamp screw and clamp. (Scheme 2) Remove right axle end first. Use a piece of wood to protect machined case surface if pipe must be pried out. Grind 1/2" from end of No. 3 screw extractor. Install No. 3 screw extractor into 3rd oil cup plug. Remove cup plug. (Scheme 2)
4. With final drive assembly and right axle shaft removed from case, inspect final drive case bushing for wear or scoring. Use Bushing Remover (J-28537-6) and Driver Handle (J-8092) to remove bushing.

Inspection

1. Inspect case assembly for damage, cracks, porosity and interconnected oil passages. Ensure exhaust vent holes are open. Inspect for stripped bolt holes.
2. Check case lugs, intermediate servo bore and snap ring grooves. Inspect case bushings for wear or scoring. Inspect drive and driven sprocket support bearing assemblies for pitting and scoring to carrier and rollers. Check rollers for excessive clearance.
3. Inspect drive and driven sprocket supports for damage to journal splines. Check for heat discoloration and cracks on support assembly. Inspect governor pipe for damage, cracks and leakage. Check parking pawl shaft cup plug, parking pawl shaft and parking pawl for damage and excessive wear. Inspect 3rd oil cup plug for tightness in bore or damage. Check all sealing and mating surfaces for straightness.

Reassembly

1. Install new final drive case bushing using Bushing Installer (J-28537-2) and Driver Handle (J-8092). Drive in bushing until tool bottoms. Using Seal Driver (J-26938 or J-29130) and driver handle, install new right axle seal assembly. DO NOT damage seal guard during installation. Using a 9/16" socket, install manual shaft oil seal with lip up.
2. Using a 1/4" drift, install new cup plug. (Scheme 2) Cup plug should seat fully in bore. Before installing, coat ends of governor oil pipe with Loctite sealer. Install governor pipe and retaining clamp.
3. Install parking pawl and spring, parking pawl shaft and retainer. Ensure large loop of pawl spring is positioned on right side of pawl. Coat parking pawl shaft cup plug with sealant, and install plug using a 3/8" drift.
4. Install driven sprocket support roller bearing assembly with bearing identification facing up. Lightly tap driven sprocket support bearing into position using Bearing Installer (J-28677). Install new converter oil seal using Driver (J-28540).

Scheme 30

1. Remove final drive internal gear and final drive internal gear thrust bearing. Lift out final drive sun gear and thrust bearing. (Scheme 28) Inspect final drive internal gear and sun gear for cracks, damage, heat discoloration and worn or missing teeth.
2. Inspect differential side gears and pinions for wear or damage. Using a 3/16" pin punch, drive out differential pinion shaft retaining pin. Remove differential pinion gears and thrust washers. Push pinion gears from differential carrier. Ensure dished pinion thrust washers are removed with pinion gears. (Scheme 30)
3. Slide differential side gears toward center of carrier and remove. Remove side gear thrust washers. Keep thrust washers with gears for reassembly reference. Ensure end play between carrier and final drive pinion is.009-.025" (.23-.64 mm).
4. Inspect final drive pinions for damage. If pinions must be removed, detach spiral retaining snap ring, and withdraw pinion pins. Carefully remove pinion gears and thrust washers together to prevent dropping needle roller bearings. Remove needle bearings from each pinion gear and check for damage. Remove governor drive gear only if replacement is necessary. Using Puller (J-8433) and a thick, flat washer, pull governor drive gear from differential.

1. If governor drive gear is removed, lightly tap it into place with a plastic mallet. Install needle bearings. Install steel pinion thrust washer onto end of pin (side opposite first thrust washer). Install one bronze pinion thrust washer to each end of pin. Slide pinion pin from assembly, keeping bearings intact in gear.
2. Install pinion gear assembly into differential carrier. Install pinion pin (stepped end last) into carrier through pinion gear assembly. Install other final drive pinion gears using same procedure. Install spiral retaining snap ring.
3. Install pinion pin so step is outside. Ensure bronze thrust washer is present on each end of final drive pinion, between carrier and steel thrust washer.
4. Install internal gear thrust bearing, sun gear with stepped side facing upward, thrust bearing with outside race to internal gear, and internal gear into final drive internal carrier. Install differential side gear thrust washers and side gears. Hold them in place with petroleum jelly. Coat side gear pinion dished thrust washers with petroleum jelly, and install them onto side gear pinions. Install pinion gears in differential carrier windows.
5. Install differential carrier case selective thrust washer into differential carrier case. Install thrust bearing into carrier assembly. Use petroleum jelly to hold bearing in place. Using Final Drive Unit Remover/Installer (J-33381), install differential carrier assembly into final drive internal case.
6. Install final drive internal gear spacer into case. Ensure parking pawl moves freely after spacer installation. Install snap ring into groove. Ensure final drive-to-case end play is.005-.032" (.12-.81 mm). See «FINAL DRIVE UNIT»(/buick/century/v-1982-1996/remont/automatic-trans/#overhaul-3t40__final-drive-unit) under TRANSAXLE DISASSEMBLY. (Scheme 31)

Scheme 31

Check final drive sun gear shaft, reaction internal gear and reaction sun/internal gear thrust bearing for excessive wear or damage. (Scheme 32) Check rear portion of center spline. If spline has a step (due to wear), replace reaction internal gear and shaft.

Scheme 32

Remove selective bearing and low roller clutch race. Pull low roller clutch from reaction carrier assembly. Remove reaction carrier-to-low roller clutch thrust washer from carrier. Pull final drive sun gear shaft from reaction internal gear. (Scheme 32)

1. Inspect low roller clutch race and roller clutch bearings for damage. Inspect 4-tanged thrust washer for scoring, excessive wear and distorted tangs. Inspect reaction carrier, roller clutch cam ramps and bushing for damage or scoring.
2. Inspect reaction carrier pinions for damage, rough bearings or excessive wear. Ensure pinion pins DO NOT rotate. Using a feeler gauge, check pinion end play. Pinion end play should be .009-.027" (.23-.69 mm).

1. Install thrust washer into reaction carrier. Ensure all rollers are installed in cage, and install roller clutch into carrier. Install clutch race. (Scheme 32) Install 4-tanged thrust washer. Use petroleum jelly to hold washer in position.
2. Install reaction carrier and clutch assembly into reaction internal gear. Install selective bearing and reaction gear assembly. Ensure gear does not contact final drive internal gear spacer.
3. Install low-reverse clutch backing plate into case with stepped side down. Install low-reverse clutch waved plate. Lubricate composition plates with ATF. Install composition plates first and then install steel plate. (Scheme 32) Install low-reverse clutch waved plate and snap ring. Snap ring is.042" (1.07 mm) thick.

Compress low-reverse clutch spring retainer, and remove snap ring. Lift out low-reverse clutch spring retainer. Remove waved release spring and clutch piston from housing. Remove inner and outer piston seals. (Scheme 32)and (Scheme 33).

Inspect clutch housing for damage or plugged feed hole. Check backing plate for cracks, damage or warpage. Inspect clutch splines and snap ring groove for damage or burrs. Remove any burrs on splines or snap ring groove. Inspect clutch piston and apply ring for distortion, cracks or damage. Inspect piston seals for nicks, cuts or hardening.

1. Install seals onto piston. Using Inner/Outer Seal Installer (J-26744-A), install clutch piston. (Scheme 32) Install clutch release spring and retainer (cupped side down). Compress retainer, and install snap ring. Apply maximum air pressure of 50 psi (3.5kg/cm(2)) to feed hole to check for proper operation.
2. Using Handle (J-34008), install low-reverse clutch housing. (Scheme 29) Ensure oil feed hole in housing lines up with feed hole in case. If housing does not go past snap ring groove, remove tool and install sun gear. Rotate sun gear back and forth until housing is in place. Install.092" (2.36 mm) thick snap ring.

Scheme 33

Scheme 34

1. Check reaction sun gear for cracks, splits, spline damage, gear-to-journal wear and plugged lubrication passages. Inspect input drum for distortion, damaged splines and pins. To check and adjust reaction sun gear-to-input drum end play, see «REACTION UNIT»(/buick/century/v-1982-1996/remont/automatic-trans/#overhaul-3t40__reaction-unit) under TRANSAXLE DISASSEMBLY.
2. Install correct thickness low-reverse housing/low race selective washer as previously determined. See LOW-REVERSE CLUTCH HOUSING-TO-LOW ROLLER CLUTCH RACE THRUST WASHER END PLAY under REACTION UNIT. (Scheme 28)and (Scheme 32).

Check all parts for pitting, scoring, damaged gear teeth and cracks. Ensure lubrication holes are open. Check input carrier thrust washers for wear and distortion of tangs. (Scheme 35) Check carrier pinion pins for tightness. Ensure pins DO NOT rotate. Ensure input carrier pinion end play is.009-.027" (.23-.69 mm).

Scheme 35

1. Place forward clutch housing in a holding fixture with clutch pack facing up. Remove snap ring, backing plate, waved steel clutch plate, composite and steel clutch plates from housing. (Scheme 36) Remove other waved steel clutch plates.
2. Using Clutch Pack Compressor (J-23456) and Adapter (J-23327-1), compress retainer and spring assembly in order to remove snap ring. Remove tools, retainer and spring assembly from clutch housing. Remove piston and insert from housing, and remove seals from piston.

Inspect input shaft oil seal rings for damage. DO NOT remove seal rings unless replacement is necessary. Inspect clutch plates and all components for excessive wear or damage and replace if necessary. (Scheme 37)

Scheme 36

Scheme 37

1. If necessary, install inner and outer seals on piston with lips facing housing. Lubricate seals, and install piston into clutch housing using Inner/Outer Seal Installer (J-26744-A).
2. Position spring guide, retainer and spring assembly into clutch housing. Compress retainer and spring assembly using compressor tool, and install snap ring. Remove compressor tool.
3. Install waved steel clutch plate. Lubricate and alternately install composition and steel plates. Install waved steel clutch plate. Install backing plate with identification side facing upward. (Scheme 34)
4. Install snap ring and new seal rings (if necessary). Using a feeler gauge, measure snap ring-to-backing plate clearance. Clearance must be.040-.060" (1.0-1.5 mm). Backing plates are available in different thicknesses. See «FORWARD CLUTCH BACKING PLATE»(/buick/century/v-1982-1996/remont/automatic-trans/#overhaul-3t40) table.
5. If removed, install new input shaft seal rings. Ensure cut ends are assembled as shown, and rings are seated in groove. (Scheme 38) Hold rings in place with petroleum jelly.

Note. Forward clutch backing plates are available in 2 materials, steel or powered metal. See FORWARD CLUTCH BACKING PLATE table for appropriate thickness code.

FORWARD CLUTCH BACKING PLATE

Scheme 38

DIRECT CLUTCH ASSEMBLY

Note. If transaxle is being serviced for a burnt intermediate band and direct clutch, new dual-land 3rd accumulator exhaust valve and conical spring must be installed.

1. Remove clutch pack snap ring. Remove backing plate, composite and steel clutch plates from clutch housing. (Scheme 39) If forward clutch is disassembled, keep direct clutch plates separate from forward clutch plates.
2. Remove snap ring holding apply ring and release spring assembly. Remove apply ring and release spring assembly from housing. Remove direct clutch piston from clutch housing. Remove inner and outer seals from piston. Remove center seal from clutch housing.

1. Inspect direct clutch housing bushings for damage, cracking or scoring. Inspect composition plates, steel plates and backing plate for wear, burning or scoring. Inspect apply ring, retainer and release spring assembly for damage.
2. Inspect direct clutch piston for distortion, cracks or damage. Inspect clutch housing for excessive wear. If there is intermediate band failure, inspect outer surface of direct clutch. (Scheme 40)
3. If removal is necessary, drive check ball capsule (toward direct clutch side of housing) from housing using a 1/4" drift. Install new capsule from direct clutch side of housing, and seat with a 1/4" drift.
4. If intermediate band/direct clutch is burned, remove intermediate servo cover and gasket. Remove 3rd accumulator exhaust valve and spring. Inspect 3rd accumulator exhaust valve bore for presence of valve seat and excessive seat wear.
5. Plug feed and release holes in bore with petroleum jelly. Install a dual-land 3rd accumulator exhaust valve. Ensure valve is centered in seat. Pour solvent into valve bore, and check for leakage on inside of case. Small amount of seepage is okay.
6. If valve leaks, replace transmission case. If valve does not leak, remove check valve, and install new conical spring onto valve (small end first). Install valve with spring into bore. Replace servo gasket and cover.

Scheme 39

Scheme 40

1. Install inner and outer seals onto pistons with lips facing away from capsule. Install center seal on housing with lip facing away from capsule. Lubricate all seals, then install piston into clutch housing.
2. Install apply ring, retainer and release spring assembly, and snap ring. Lubricate direct clutch plates with ATF and install into housing, starting with a flat steel plate, and then alternating between composition and flat steel plates. Ensure smooth fiber composition plates are used. (Scheme 37)and (Scheme 39).
3. Install snap ring. Install backing plate into housing with chamfered or polished side facing up. Install second snap ring. Ensure composition plates turn freely.

Inspect intermediate band for burns, flakes or damage. Install intermediate band, aligning lugged end with apply pin bore. Install band anchor hole plug.

1. Inspect driven sprocket support and sleeve for damage. Ensure sleeve is tight in bore and aligns with holes in support. Inspect driven sprocket support bushing and bearing assembly for damage and wear. (Scheme 27)
2. Pull out bearing assembly using slide hammer and Bearing Remover (J-26941). Using Bearing Installers (J-28677 and J-8092), install bearing with identification facing up.
3. Check bearing race on driven sprocket. If race needs replacement, replace driven sprocket support. Inspect seal rings for nicks or cuts. Replace worn or damaged components as needed.

1. Inspect manual valve rod, rod retainer and detent lever for damage. (Scheme 25) Check threads of manual shaft, and file any raised edges.
2. Inspect parking lock actuator rod for damage or broken retainer lugs. If removed, install parking lock actuator rod into manual shaft lever. Use a 3/16" drift and install roll pin into detent lever. Tap nail into place.

1. Inspect drive chain for damage. With drive link assembly installed, check chain slack. If slack is more than 1 1/16", replace drive chain.
2. Inspect driven sprocket thrust bearing race. (Scheme 47) If damaged, replace driven sprocket, drive sprocket (flat side up) and drive support bearing assembly. Inspect drive sprocket teeth for nicks, burrs, scoring and wear.
3. Check internal splines for nicks, burrs and excessive wear. Inspect turbine shaft for excessive wear or damage. Inspect turbine shaft seal ring grooves and seal rings for damage.
4. DO NOT remove seal rings unless they are being replaced. If turbine shaft seal ring removal is necessary, carefully cut old seals from turbine shaft. Install new seals.
5. Use Sizer (J-29569-2) on 2 seal rings on valve body side of sprocket. Use seal installer on seal ring on case side of sprocket. Push sizer down over seal and turn. Remove sizer, and inspect seal to ensure it is seated in groove.

CASE COVER

Note. DO NOT disassemble case cover unless repair or replacement of cover or components is necessary.

Remove detent spring/roller assembly retaining screw, and remove spring/roller assembly. Remove 2 thermostatic roll pin retainers. Remove thermostatic element and plate. Remove axle oil seal and guard if necessary. Using a drift, drive out manual valve cup plug. Carefully withdraw manual valve. DO NOT use manual valve to drive out cup plug.

1. Inspect case cover and threads for damage. Inspect vent assembly for damage and clogging. Check manual valve movement. Check manual valve electrical connector and replace if necessary. Inspect manual detent spring and roller assembly. Check case cover sleeve. Ensure hole in sleeve aligns with case cover passages that intersect case cover (pump shaft) bore.
2. Inspect 1-2 accumulator piston seals for damage and free fit in grooves. Inspect thermostatic element for damage or distortion. Inspect vent assembly and cooler line connectors for damage. Replace components if necessary.

1. Install new axle oil seal and seal guard. Install detent spring and roller assembly. If 1-2 accumulator piston seal was removed, install new seal ring. Install 1-2 accumulator piston (flat side down).
2. Install 1-2 accumulator piston pin. Install manual valve assembly with small diameter first. Using a 3/8" drift, replace manual valve cup plug. Coat cup plug with sealant before installation. With new "O" ring on electrical connector, install connector with tab located at case slot.
3. If removed, install thermostatic element roll pins into case. Using Roll Pin Height Checker (J-29023), adjust installed height of center roll pin to.24" (6 mm). (Scheme 41) Recheck thermostatic element roll pin installed height. Install thermostatic element plate.
4. Install thermostatic element onto roll pins. Place Roll Pin Height Checker (J-29023) against roll pin, between case surface and thermostatic element. Install roll pin retainers, and tap down onto roll pins until element contacts touch. Set roll pin washer height after installing and setting center roll pin height.
5. Set roll pin retainer height to.21" (5.3 mm). (Scheme 42) Adjustment is important for thermostatic element operation. Thermostatic element controls fluid level in control valve cover oil sump.

Scheme 41

Scheme 42

CONTROL VALVE BODY & OIL PUMP ASSEMBLIES

Note. As valve components are removed from valve body bore, place individual parts, in correct order, in relative position to valve body. Valves, bushings and springs are not interchangeable. (Scheme 43)

1. Position control valve body with cored face up and line boost valve at top. Remove roll pins. Pull all blind hole roll pins from valve body. If valve body is cleaned in solvent, low blow-off assembly must be replaced. CAUTION: Many roll pins in valve body have pressure exerted against them. Use caution when removing pins.
2. Remove auxiliary valve body cover screw, auxiliary valve body, gasket and cover. Remove pump slide, rotor, vanes and vane rings.

1. Clean all components. DO NOT clean pump seals in solvent. Check all parts for wear or damage. Replace pump shaft bearing assembly using Bearing Remover/Installers (J-35914 and J-7092-2). Drive bearing out toward case cover side. Using bearing installers, press bearing and seal assembly flush to .012" (.3 mm) below pump pocket.
2. Measure the pump rotor and/or slide thickness. Measure on flat, undamaged surface. Use original measurement when obtaining replacement parts. Pump rotor thicknesses range from .7052-.7071" (17.912-17.962 mm) in .0004" (.009 mm) increments. Hone both sides of replacement rotor and/or slide to remove burrs.

1. Install pump slide into pump pocket. Install pump slide seal and seal support. Use petroleum jelly to retain slide parts. Align slide with pump slide pivot hole, and install pump slide pivot pin. Install vane ring and pump rotor into pump pocket. Install pump vanes into pump.
2. Ensure pump vane wear pattern is against centering ring, and each pump vane is seated flush with rotor. Install top vane ring and slide "O" ring seal in pump slide.
3. Install pump slide-to-auxiliary valve body oil seal ring. Check auxiliary valve body sleeve for damage. Install auxiliary valve body, gasket and cover. Align pump rotor step with auxiliary valve body sleeve. To complete reassembly, reverse disassembly procedure. (Scheme 43)

Scheme 43

Scheme 44

Remove auxiliary valve body components. (Scheme 43)or (Scheme 44). Keep parts in order for reassembly reference.

Clean all parts, except solenoid and switches, in solvent. Inspect all parts for wear or damage.

1. To reassemble, reverse disassembly procedure. Ensure auxiliary valve body sleeve is aligned with step in pump rotor. Before installing solenoid, locate metal clip attached to valve body and discard. Install solenoid with new "O" ring and plastic wire routing clip. Install cover gasket and screw.
2. Ensure valve body bolt sizes are correct. Coat threads of bolt "F" with sealant before installation. (Scheme 54) Tighten bolts to specifications. See «TORQUE SPECIFICATIONS»(/buick/century/v-1982-1996/remont/automatic-trans/#overhaul-3t40__torque-specifications).

Disassembly & Reassembly

Remove snap ring from apply pin (if not previously done). Separate intermediate servo piston, spring retainer and apply pin. Remove and discard "O" ring seals. (Scheme 45) Check all parts for wear or damage. Intermediate servo is assembled during transaxle assembly. See TRANSAXLE REASSEMBLY.

Scheme 45

1. Check governor assembly for wear or damage. Ensure governor weights operate freely and independently of each other. Check for damaged, mispositioned or tilted springs.
2. Install governor cover with new "O" ring. Ensure governor shaft is piloted in cover before tightening retaining bolts. Install speedometer drive gear/speed sensor housing. (Scheme 46)or (Scheme 47).

Scheme 46

Scheme 47

Scheme 48

Scheme 49

Scheme 50

TRANSAXLE REASSEMBLY

Note. Note location of all gear sets, clutch plates, thrust bearings, thrust washers and bushings. (Scheme 48)and (Scheme 49). Recheck snap ring and thrust washer measurements taken during disassembly. See appropriate procedures under COMPONENT DISASSEMBLY & REASSEMBLY.

Scheme 51

Scheme 52

Scheme 53

Scheme 54

Scheme 55

1. Lubricate all bushings, seals, thrust bearings and internal mating surfaces with ATF during reassembly. Use petroleum jelly to hold thrust washers in place.
2. Install selected differential carrier/case thrust washer. (Scheme 30) Install thrust bearing assembly to final drive unit (inner race of bearing against selective washer). Install differential and final drive assembly into case.
3. Install final drive internal gear spacer (cupped side against final drive internal gear). Ensure opening in spacer aligns with parking pawl opening in case. Ensure parking pawl passes through spacer.
4. Install final drive spacer-to-case snap ring with ring gap away from parking pawl opening in case. Install reaction sun gear set into case. (Scheme 32)
5. Install low-reverse clutch backing plate (stepped side down) and clutch plates into case. (Scheme 32) Start with a composition plate, and then alternate between steel and composition plates.
6. Install low-reverse clutch wave plate and thin housing-to-case spacer ring. Install low-reverse clutch housing assembly into transaxle case. (Scheme 32) Ensure clutch feed hole in housing lines up with clutch feed hole in case.
7. Install selective snap ring onto reaction sun gear. Install reaction sun gear onto final drive sun gear shaft in transaxle. (Scheme 32)and (Scheme 35). Rotate reaction sun gear while pushing down on low-reverse clutch housing until clutch housing drops below snap ring groove in case.
8. Install thick low-reverse clutch housing-to-case snap ring. (Scheme 32) Install input drum onto reaction sun gear. (Scheme 35) Install input sun gear into input drum. Install input sun gear tanged thrust washer to pinion side of carrier.
9. Install input internal gear tanged thrust washer to internal gear side of carrier (input internal gear tanged thrust washer is larger than input sun gear tanged thrust washer). (Scheme 35) Install input pinion carrier onto input sun gear.
10. Install input internal gear over input carrier. Place forward clutch assembly on bench with input shaft up. Install direct clutch assembly over input shaft, onto forward clutch housing. When clutch housings are fully seated, distance from tang end of direct clutch housing to end of forward clutch housing should be 1.406" (35.71 mm). (Scheme 51)
11. Install input shaft-to-input internal gear thrust washer onto forward and direct clutch assembly. (Scheme 35)and (Scheme 48). Ensure rounded side is against input shaft, and stepped side faces outward, onto forward and direct clutch assembly.
12. Install direct and forward clutch assemblies into case. Rotate clutch assemblies, without pushing down, until they drop into fully seated position in case. When correctly installed, case face-to-direct clutch housing distance should be 1 11/16". (Scheme 52)
13. Install intermediate band. Install band anchor hole plug. Install driven sprocket support-to-direct clutch housing thrust washer. Install driven sprocket support. (Scheme 27)
14. Install manual shaft and parking lock actuator rod into case through driven sprocket support. Install detent lever on manual shaft (hub side away from driven sprocket support), and push manual shaft in place. Install detent lever-to-manual shaft retaining pin. Install manual shaft-to-case retaining nail. (Scheme 27)
15. Assemble drive and driven sprockets with link assembly, and install drive and driven thrust washers to sprockets. Install drive link assembly onto transaxle. (Scheme 2) The colored guide link must face case cover.
16. Install case cover-to-driven sprocket roller bearing thrust washer (outer race against sprocket). Install 1-2 accumulator piston. Install thermostatic element (if removed). See CONTROL VALVE BODY & OIL PUMP ASSEMBLIES under «COMPONENT DISASSEMBLY & REASSEMBLY»(/buick/century/v-1982-1996/remont/automatic-trans/#overhaul-3t40__component-disassembly-reassembly).
17. Install 1-2 accumulator spring into bore in case. Install inner and outer case-to-cover gaskets and case cover. Install and tighten all case cover bolts. (Scheme 53) Install 2 case cover bolts from inside torque converter housing (M8 x 1.25 x 14 mm). Install remaining case cover bolts. The 3 bolts that mate sprocket support-to-case cover must be tightened evenly to avoid cocking sprocket support.
18. Connect manual valve rod to manual valve. Install check balls No. 2-6 into case cover. (Scheme 22) Install No. 1 check ball on direct clutch passage on spacer plate. Install oil pump shaft into bore in case cover. Install 2 guide pins (M6 x 1.0 x 75 mm) in case cover-to-valve body bolt holes.
19. Install control valve body and bolts. (Scheme 54) Tighten bolts to specification. See «TORQUE SPECIFICATIONS»(/buick/century/v-1982-1996/remont/automatic-trans/#overhaul-3t40__torque-specifications). Install valve body wiring harness. Ensure wiring harness is routed properly. (Scheme 56) Connect lever link to T.V. bracket. Install T.V. bracket onto valve body.
20. Remove guide bolts used to install valve body, and install remaining 2 valve body bolts. Thoroughly clean valve body cover. Install cover with new gasket. Apply Loctite sealant to indicated cover bolts. (Scheme 55)
21. Turn transaxle so oil pan side is up. Install output shaft into transaxle. (Scheme 2) Rotate final drive so retaining ring groove is visible through access window in case. Install new retaining ring onto shaft groove.
22. Install parking lock bracket and dipstick stop. Using a 3/8" drift, install new low-reverse oil pipe seal assembly. Install "O" ring backup washer and "O" ring seal onto end of low-reverse pipe. Install pipe and retainer bracket.
23. Install intermediate servo piston assembly. Use new inner and outer oil seals on piston and new seal on apply pin (apply pin size was determined during transaxle disassembly procedure). Install 3rd accumulator exhaust valve and spring into check valve bore next to servo piston. Install intermediate servo cover and 3 bolts. (Scheme 17)
24. Install reverse oil pipe bracket to oil pipe and servo cover. Install remaining servo cover bolt through bracket and cover. Tighten servo cover bolts. Install new oil strainer and "O" ring. Install oil pan gasket and oil pan. Apply Loctite sealant to oil pan bolt threads. (Scheme 55) Rotate transaxle so oil pan side is down.
25. Install governor assembly. Install new "O" ring to governor cover, and install cover onto case. Install speedometer/speed sensor driven gear assembly into governor cover. Ensure governor shaft is piloted in governor cover before tightening cover bolts. Install torque converter.

TRANSAXLE SPECIFICATIONS

TRANSAXLE SPECIFICATIONS

TORQUE SPECIFICATIONS

TORQUE SPECIFICATIONS

WIRING DIAGRAMS

Note. For additional vehicle chassis transaxle circuit wiring information, see 2.2L Engine Performance Wiring Diagrams or 3.1L Engine Performance Wiring Diagrams .

Scheme 56

See also:
• TRANSMISSION SERVICING - A/T
• AXLE SHAFTS - FRONT
• TRANSMISSION REMOVAL & INSTALLATION - A/T
• CONTROL VALVE BODY & OIL PUMP ASSEMBLY
• TCC TESTING
• LINE PRESSURE TESTS
• INTERMEDIATE BAND APPLY PIN
• FINAL DRIVE UNIT
• REACTION UNIT
• TORQUE SPECIFICATIONS
• TRANSAXLE REASSEMBLY
• COMPONENT DISASSEMBLY & REASSEMBLY