OBJECTIVES Describe the automatic transmission overhaul procedures.

OBJECTIVES Describe the automatic transmission overhaul procedures.
After studying Chapter 16, the reader should be able to: Describe the automatic transmission overhaul procedures. Perform the automatic transmission disassembly inspection procedure. Properly disassemble and reassemble an automatic transmission. Complete the ASE tasks related to off-vehicle transmission/transaxle repair.

INTRODUCTION A badly worn or damaged transmission is removed from the vehicle for repair, and there are essentially four repair choices: Repair or replace the worn/damaged component, Overhaul the transmission Replace the transmission with an exchange/used Install a remanufactured transmission. When the overhaul is done by a technician working at an automotive repair facility, it will be guaranteed by the shop.

INTRODUCTION Overhauled Transmissions Remanufactured Transmissions
Transmission Parts Overhaul Procedure To overhaul or rebuild an automatic transmission, you should:

INTRODUCTION FIGURE 16-1 A remanufacturing assembly line. The valve bodies are moving from left to right as they are being assembled; the computer identifies which parts are to be installed and their location (a). The transmissions also move along an assembly line; each station has a monitor to show the operation, the parts to be installed, and the special tools to install them (b). (Courtesy of Williams Technologies Inc., Div. of Delco Remy International, Inc.)

INTRODUCTION FIGURE 16-2 Aftermarket sources can provide most of the parts needed to repair a transmission as well as supplemental parts and information. (Courtesy of Slauson Transmission Parts,

INTRODUCTION FIGURE 16-3 The soft parts required to rebuild a transmission are available as kits. The contents of a kit will vary with different suppliers.

TRANSMISSION DISASSEMBLY
The disassembly procedure for a transmission varies between makes and models. Special tooling or procedures are often required. FIGURE 16-4 These special tools are used when rebuilding a THM 350. (Courtesy of ATEC Trans-Tool and Cleaning Systems)

FIGURE 16-4 (CONTINUED) These special tools are used when rebuilding a THM 350. (Courtesy of ATEC Trans-Tool and Cleaning Systems)

Predisassembly Cleanup Cleanliness is a must during a transmission overhaul. Many shops steam clean or pressure wash the outside of the transmission as soon as it is removed from the vehicle. FIGURE 16-5 This transmission is being cleaned using a hot, highpressure washer. A thorough cleaning makes it easier to locate and remove bolts and retaining rings and keeps the work area cleaner.

Torque Converter Removal The converter is removed from the vehicle with the transmission. It is then removed from the transmission by sliding it out the front of the transmission. Disassembly Fixtures During disassembly, the transmission is placed on the bench and torn down. It is usually placed upside down and rolled over as needed.

FIGURE 16-6 A transmission-holding fixture (arrows) has been mounted onto this transmission. It will allow the transmission to be rotated to the best working position. The round stem at the left will be slid into a bench fixture.

TECH TIP Some shops use a simple fixture that resembles a threelegged stool; other shops simply use an old transmission case in a rear-side-up position. FIGURE 16-7 This simple, shop-made stool (a) has a hole for the transmission output shaft (b). The output shaft of this transmission being repaired has been placed through the rear opening of an empty case (c). Caution should be exercised if using either support method. Because of the narrow bases, they can tip over.

PRELIMINARY DISASSEMBLY
The first teardown step is to remove the oil pan, filter, and valve body. Many technicians use the oil pan to store the retaining rings, screws, bolts, and other small parts removed during disassembly. The procedure is to remove the pan, inspect the debris (if it has not been done already), wash the pan in solvent, and air dry it Next, the filter and gasket are removed and set aside for comparison with the new filter. The valve body is then removed and set aside for cleaning and inspection

FIGURE 16-8 The valve body can be removed after the pan. Some valve bodies have a throttle cable or fluid tubes that need to be disconnected.

Some transmissions use steel tubes to transfer a fluid passage from one location to another. These tubes normally use an O-ring to seal each end and are held in place by a retaining bracket. FIGURE 16-9 Oil tubs/pipes are removed by gently prying upward. Note the block of wood to protect the case. (Courtesy of Toyota Motor Sales USA, Inc.)

FIGURE This transmission has four accumulators under the valve body (a). Note the differences in the springs and pistons and remove them. Compressed air can be used to lift the piston out of its bore (b).

FIGURE The punch is passing through a hole in the case to push the retaining ring out of the groove. This allows a seal pick or small screwdriver to pry the retaining ring out. FIGURE This accumulator cover retaining ring is being removed using a pair of snap ring pliers. Some can be pried out of the groove and bore using a small screwdriver or seal pick. (Courtesy of Chrysler Corporation)

FIGURE This accumulator plate/cover is retained by a retaining ring, and the accumulator spring is pushing upward on the cover (a). With the cover removed, the piston and spring can be removed (b). (Courtesy of Chrysler Corporation)

SPECIAL NOTES ON RETAINING RINGS
A retaining ring is commonly used to hold a part in place. It can hold a gear in position on a shaft or a servo cover in a bore. FIGURE The most common styles of retaining rings are external, pin type (a), internal pin type (b), plain external (c), plain internal (d), and E-clip (e).

SPECIAL NOTES ON RETAINING RINGS
FIGURE Snap ring pliers for external pin type (a), internal pin type (b), and three different styles for plain external snap rings (c–e). The bottom pliers have jaws that open in a parallel action. (Courtesy of Snap-On Tools)

End-Play Check It is standard practice to measure the input shaft end play before removing the pump. End play is the in-and-out movement of the shaft. To measure input shaft end play, you should do the following: FIGURE Input shaft end play is an important check for internal wear in a transmission. Note that a more accurate check is made if the input shaft is vertical. (Courtesy of Chrysler Corporation)

FIGURE The dial indicator can be attached to the transmission case or pump (left) or to the input shaft (right). Moving the input shaft will show the end play on the indicator dial.

FIGURE This special tool is used to pull the pump. It can also be attached to the input shaft to allow the shaft to be lifted so end play can be measured.

TECH TIP The measuring stylus must be parallel to the input shaft.
The indicator body should be adjusted to load the stylus about one full needle rotation FIGURE A dial indicator should be set up with the indicator stem parallel to the input shaft and the stem is loaded about one revolution of the indicator dial (1). Next, move the input shaft completely into the transmission (2),and rotate the dial to zero the needle (3).When the input shaft is lifted, the amount of end play can be read on the indicator dial.

FIGURE These special tools allow measuring gear train end play so that it can be properly adjusted. (Courtesy of Chrysler Corporation)

FIGURE This transmission uses 12 different selective thrust plates for the No. 4 position. The proper thrust plate is selected to adjust the input shaft end play. (Courtesy of Chrysler Corporation)

Other Predisassembly Checks FIGURE This special tool is used to measure the servo piston rod stroke as the servo is applied. A different piston rod can be installed if needed. (Courtesy of Toyota Motor Sales USA, Inc.)

PUMP REMOVAL The pump assembly is the front cover that holds the gear train inside the case on RWD transmissions. Its removal allows the disassembly of the rest of the internal parts. The pump is held in place by a set of bolts. The close fit between the outer pump diameter and the case plus a rubber sealing ring and/or gasket makes pump removal a little difficult. Several methods can be used to remove the pump. These include slide hammers, special screw-type pullers, and prying on the gear train.

PUMP REMOVAL To pull a pump using slide hammers, you should do the following: To pull a pump using a screw-type puller, you should do the following: To pull a pump by prying, you should:

PUMP REMOVAL FIGURE This section of a front pump shows a hole that has internal threads to accept a slide hammer.

PUMP REMOVAL FIGURE A pair of slide hammers has been threaded into the pump assembly (a). After the pump has pulled free, the tools are used to lift the pump out of the transmission (b). (Courtesy of Chrysler Corporation)

PUMP REMOVAL FIGURE This special service tool is attached to the front pump. Turning the center bolt will push against the input shaft to lift the pump from the transmission.

PUMP REMOVAL FIGURE Tool J24773-A is connected to the front pump, turning the center bolt will lift the pump (a). A similar tool is attached to this pump (b). An aftermarket tool will serve the same purpose on a variety of pumps; note the valve protector (arrow) to prevent damage to the check valve at the end of some input shafts.

PUMP REMOVAL Transaxles Using Input Chain Drive
Some transaxles use a chain and sprockets for gear train input. The main gear train is behind the valve body; case cover, channel plate, or chain cover; and drive chain and sprockets. FIGURE Removal of the upper pan/chain cover (361), valve body and pump (419 and 320), and the channel plate (280) allows access to the sprockets (575 and 602) and drive chain (82) along with the other parts of the gear train. (Courtesy of Slauson Transmission Parts,

PUMP REMOVAL FIGURE Drive chain and sprocket wear is normally checked by moving the chain inward and outward. Excess movement indicates excessive wear. (Courtesy of BergWarner,Morse TEC)

PUMP REMOVAL FIGURE The drive chain and the sprockets can be lifted off the case. Note the position of the master link, where the thrust washers are, and how they fit onto the sprockets as you remove them. They must be replaced correctly in this same position. (Reprinted with permission of General Motors)

MAJOR DISASSEMBLY A service manual should be followed for the disassembly procedure. Some transmissions almost fall apart after the pump is removed; others come apart one piece at a time. To complete transmission disassembly, you should:

MAJOR DISASSEMBLY FIGURE This input shaft and clutch hub with planetary gears is lifted out of the case. (Courtesy of Toyota Motor Sales USA, Inc.) FIGURE Removal of the band strut frees this band so it can slide out of the case. (Courtesy of Chrysler Corporation)

MAJOR DISASSEMBLY FIGURE This governor assembly is being removed from the transfer shaft of this transaxle. (Courtesy of Chrysler Corporation) FIGURE Removal of the retaining bolts allows the extension housing and overdrive unit to be removed from this 42RH transmission. (Courtesy of Chrysler Corporation)

MAJOR DISASSEMBLY FIGURE The entire gear train of some transmissions is removed as an assembly (a). The gear train of other transmissions is removed one section at a time (b).

MAJOR DISASSEMBLY FIGURE (CONTINUED) The entire gear train of some transmissions is removed as an assembly (a). The gear train of other transmissions is removed one section at a time (b).

MAJOR DISASSEMBLY FIGURE Parts 7376, 2341, 9891, and 250 are thrust washers that keep parts properly separated. Parts 9861,7645,3956,7831,8643,and 3485 are retaining rings that hold components in the proper position. (Courtesy of Slauson Transmission Parts,

TECH TIP During disassembly, it is a good practice to place index marks on both parts. FIGURE It is a good practice to place index marks on the driving lugs (arrows) so the direct clutch shell and the low/intermediate ring gear can be assembled in the original position.

MAJOR DISASSEMBLY FIGURE Like a center support, this clutch pack is retained by a large retaining ring (a). A large screwdriver can be modified to hook the retaining ring for quick and easy removal (b). The special tool is being used to lift the overdrive support assembly (c). (a is courtesy of Chrysler Corporation)

MAJOR DISASSEMBLY FIGURE The low/reverse support/anticlunk spring (680) is removed with the low/reverse support. (Reprinted with permission of General Motors)

MAJOR DISASSEMBLY FIGURE The retaining ring (a) locates the clutch pack in the rear of this case (b).

MAJOR DISASSEMBLY FIGURE The special tool is used to compress the clutch piston return springs (a) so the retaining ring can be removed (b).

SAFETY TIP When using a spring compressor, compress the springs just enough to allow the snap ring to be removed. FIGURE With the retaining ring removed, slowly release the spring compressor; make sure that the spring retainer does not catch on the snap ring groove.

MAJOR DISASSEMBLY FIGURE Removal of the bracket allows the park rod to be removed (a). Then the park/lock pawl and shaft can be removed (b).

MAJOR DISASSEMBLY FIGURE After removing the carrier cover (a), the differential case can be removed from this transaxle (b).

TRANSMISSION ASSEMBLY
The reassembly procedure for an automatic transmission varies depending on the make and model of the transmission. A service manual should be followed to make sure the parts are assembled in the right order and position and that important checks and adjustments are not skipped. FIGURE This retaining ring locates the overdrive support assembly; note how the tapered side is positioned toward the front of the case.

FIGURE Checking the differential or gear train end play ensures that the thrust washers have the proper clearance. Note that some transmissions require a special tool to lift the gear train. (Courtesy of Chrysler Corporation)

FIGURE Transmission assembly lubricant or petroleum jelly can be used to lubricate parts and hold them in the proper position.

FIGURE Thrust bearings and their races must be assembled correctly.

FIGURE This transaxle uses a hypoid ring and pinion gearset that requires additional adjustment as it is assembled. (Courtesy of Chrysler Corporation)

Pump Installation and End-Play Adjustment The final assembly point of many gear trains is the pump. A new pump gasket must be used. Many technicians use two guide pins to hold the gasket in place and align the pump as it is installed.

TECH TIP FIGURE This overrunning clutch assembly with the inner cam, rollers, and springs should be installed into the clutch drum using a counterclockwise rotating motion. (Courtesy of Chrysler Corporation) As a one-way clutch is assembled, it should be checked to make sure it freewheels in one direction and locks in the other.

TECH TIP A one-way roller clutch also can be assembled improperly.
The accordion spring should preload the rollers in the lockup direction, and, if possible, place the spring so it will tend to move away from freewheeling race FIGURE The accordian spring in some one-way clutches can be installed in a direction so that it will rub against the inner race. This can cause wear and breaking of the spring.

TECH TIP A center support with a clutch piston must have a fluid passage between it and the case. This passage is often sealed with a special seal that is installed after the center support is installed. FIGURE After this center support (640) with the rear gear assembly (651) is installed (a), it must be positioned properly using tool J23093 before the retaining bolt (25) is installed (b). On some transmissions, a tube seal should be installed as shown to prevent fluid leaks in the center support and its clutch. (Reprinted with permission of General Motors)

TECH TIP A clutch should be stacked with the plates in the proper order and position. There should also be the proper clearance in the clutch stack. FIGURE With the clutch stack correctly installed (a), the pack clearance can be measured using a feeler gauge (b) or a dial indicator (c). Applying the clutch with air allows the piston travel/pack clearance to be measured (d). (Courtesy of Toyota Motor Sales USA, Inc.)

TECH TIP FIGURE (CONTINUED) With the clutch stack correctly installed (a), the pack clearance can be measured using a feeler gauge (b) or a dial indicator (c). Applying the clutch with air allows the piston travel/pack clearance to be measured (d). (Courtesy of Toyota Motor Sales USA, Inc.)

TECH TIP As a clutch is assembled, it can be air checked by applying air pressure into the apply passage. FIGURE After the clutch is completely installed, its operation can be checked by applying compressed air to the fluid passage.

TECH TIP FIGURE These front and rear clutches are installed together. The lugs of the front clutch must engage the notches in the sun gear shell, and the rear clutches must engage the splines on the clutch hub. Swinging the input shaft in a spiral motion can help align the plates. (Courtesy of Chrysler Corporation)

TECH TIP You can determine if a clutch is completely installed by measuring its position in the transmission case FIGURE The straightedge is used to check the depth of the parts. If the two surfaces are flush, they are assembled correctly. (Reprinted with permission of General Motors)

FIGURE The two pilot studs/guide pins properly align the gasket and pump to the transmission case as the pump is installed. (Courtesy of Chrysler Corporation)

FIGURE An H-shaped gauge is being used to check end play (a). It is adjusted to fit the transmission (left) and then moved to check the clearance at the pump (right). A shop-made gauge can be used in the same manner; note the use of an old band to support the gauge at the pump.

FIGURE After the dial indicator is set up, lifting and dropping the input shaft shows the amount of end play. If it is correct, the internal parts have been installed correctly.

FIGURE In most transmissions, the No. 1 (fiber) washer is selective. The technician selects the proper size to adjust the end play. (Courtesy of Chrysler Corporation)

Torque Converter Installation The converter must align at three points: turbine spline, stator spline, and pump. Most converters use two flats or notches that engage the pump drive gear, and these notches should be positioned to align with the pump drive gear before installation FIGURE A torque converter must fully engage the pump, stator support, and turbine shaft (circles).

FIGURE This check ensures that the torque converter is installed completely into the transmission. (Courtesy of Chrysler Corporation)

TECH TIP If a torque converter depth dimension is not available, pump tang engagement can be checked by noting how deep the converter is in the housing, rotating the converter a turn or so, lifting the converter back out, and noting if the pump drive tangs are aligned with the location of the converter hub. FIGURE The torque converter was rotated and then removed. The pump drive lug (circle) must align with the position of the converter drive tang.

FIGURE A transmission is installed in this tester. It will be driven at various speeds while loads are applied to the drive train. (Courtesy of Axiline)

SUMMARY Automatic transmissions are removed from a vehicle for overhaul, repair, or replacement. A transmission overhaul includes inspection of all reusable parts, a check of the clearances, and replacement of all gaskets, seals, friction materials, the filter, and worn bushings. Remanufactured transmissions have been overhauled and updated in a factory-like environment. Transmission parts are classified as hard or soft parts. Hard parts are not commonly replaced. Soft parts are commonly replaced during an overhaul. Although the overhaul procedures for various transmissions are similar, there are differences, and service information should always be consulted when overhauling or servicing an automatic transmission.

REVIEW QUESTIONS The three repair choices for a badly worn or damaged transmission are: _________ _________ parts are replaced during an automatic transmission overhaul. _________ parts include the pump, clutch drums, and gearsets. To learn about possible health problems and special handling requirements, refer to the _________ _________ _________ _________ (MSDS). Excessive end play is a result of _________ wear.

REVIEW QUESTIONS Transmission end play is normally measured with a _________ _________. A technician will change a _________ thrust washer or _________ ring to correct transmission end play. Before reassembly, the parts are washed an _________ dried. As a one-way clutch is assembled into the transmission, it should be checked to ensure that it _________ in the right direction. After a clutch pack is assembled, it should be _________ _________ checked to ensure proper operation.

REVIEW QUESTIONS Most technicians set the _________ _________ to the tight side of the specifications. During assembly, all of the friction elements should be _________ in ATF. During assembly, all of the hydraulic units should be _________ checked. The torque converter must align at three points. What are they? _________ 15. Damage could result to the pump or torque converter if the _________ _________ is not properly installed.

CHAPTER QUIZ Student A says that some states have rules and regulations that define what an automatic transmission rebuild or overhaul must include. Student B says that an alternative to an overhaul is to replace the transmission with a remanufactured transmission. Who is correct? Student A Student B Both A and B Neither A nor B

CHAPTER QUIZ 2. Student A says that the torque converter should be left attached to the engine when the transmission is removed from a vehicle. Student B says that the torque converter should be disconnected from the engine and removed with the transmission. Who is correct? Student A Student B Both A and B Neither A nor B

CHAPTER QUIZ 3. Student A says that the transmission must be thoroughly cleaned right after removal. Student B says that most transmission-holding fixtures allow the student to move the transmission to the best working position. Who is correct? Student A Student B Both A and B Neither A nor B

CHAPTER QUIZ 4. Student A says that some servos and accumulators require special holding tools or spring compressors to hold the internal spring compressed during disassembly. Student B says that an end-play check should be made before removing the transmission pump. Who is correct? Student A Student B Both A and B Neither A nor B

CHAPTER QUIZ 5. Student A says that the old gaskets should be discarded as they are removed from the transmission. Student B says that the old gaskets should be saved to match with the new gaskets during assembly. Who is correct? Student A Student B Both A and B Neither A nor B

CHAPTER QUIZ 6. Student A says that excessive transmission end play is usually caused by a stretched case. Student B says that loose pump bolts are the major cause of excess end play. Who is correct? Student A Student B Both A and B Neither A nor B

CHAPTER QUIZ 7. During a transmission rebuild, it is good practice to replace rubber sealing rings. lined clutch plates. paper and composition gaskets. All of these

CHAPTER QUIZ 8. Student A says that special slide hammers are used to pull the pump assembly from the case. Student B says that air pressure in the proper port helps pull the pump. Who is correct? Student A Student B Both A and B Neither A nor B

CHAPTER QUIZ 9. After the case has been cleaned it should be checked for damage, warpage, and cross leaks at the worm tracks. a worn governor bore. damaged bolt threads. All of these

CHAPTER QUIZ 10. Student A says that worn or damaged bushings are repaired by driving them out and replacing them with new bushings. Student B says that some bushings are removed by cutting threads in them so a puller bolt can be used. Who is correct? Student A Student B Both A and B Neither A nor B

CHAPTER QUIZ 11. Student A says that it is good practice to replace all of the friction materials (lined plates, unlined plates, and bands) when rebuilding a transmission. Student B says that lined friction material must be soaked in ATF before it is installed. Who is correct? Student A Student B Both A and B Neither A nor B

CHAPTER QUIZ 12. Student A says that you should ensure the cleanness of all internal parts by wiping them with a clean shop cloth just before installation. Student B says that petroleum jelly is a good stickum for thrust washers as well as being a good assembly lubricant. Who is correct? Student A Student B Both A and B Neither A nor B

CHAPTER QUIZ 13. Student A says that all parts should be thoroughly checked for cleanliness and proper working order during reassembly. Student B says that some transmissions have several end-play checks that must be done as the transmission is assembled. Who is correct? Student A Student B Both A and B Neither A nor B

CHAPTER QUIZ 14. Student A says that transmission end play is normally measured using a dial indicator mounted at the turbine shaft. Student B says that transmission end play is always corrected at the thrust washer No. 1 next to the pump. Who is correct? Student A Student B Both A and B Neither A nor B

CHAPTER QUIZ 15. Student A says that all the clutches and servos should be air checked right after the valve body has been installed. Student B says that all transmission bolts and especially the valve body bolts should be tightened to the correct torque. Who is correct? Student A Student B Both A and B Neither A nor B

OBJECTIVES Describe the automatic transmission overhaul procedures.

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OBJECTIVES Describe the automatic transmission overhaul procedures.

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