Automatic Transaxle Overhaul & Testing - 4T80-E: Overhaul Oldsmobile Aurora I

CASE ASSEMBLY

Remove torque converter, turbine shaft "O" ring, oil pump drive shaft, output speed sensor and oil cooler fitting from extension housing. While holding servo cover in place, remove 4th servo from case. DO NOT allow servo cover to tilt during removal or case damage may occur.

FINAL DRIVE END PLAY CHECK & ASSEMBLY PROCEDURE

1. Mount Dial Indicator Post (J-39687) and Dial Gauge (J-8001-3) to check end play. Pry up on speed sensor rotor through output speed sensor hole. End play should be.006-.025" (.15-.65 mm). (Scheme 25) Record this measurement for reassembly.
2. Remove case extension, thrust washers and seal. Remove scavenge tube and seal from transaxle case. Lock parking gear with park actuator. Remove 4 differential bolts and differential carrier.
3. Push on output shaft and remove snap ring. Remove left differential gear and remove output shaft from front end of transaxle. Remove final drive carrier, thrust bearing, final drive sun gear and internal gear.

Scheme 25

LOWER TRANSAXLE ASSEMBLY

Remove bottom oil pan and oil scavenger screens. Disconnect manual valve link and wiring harness connectors. Remove oil transfer plate. Leave specified bolts in assembly to hold lower control valve and accumulator assembly together. (Scheme 26) Remove control valve and accumulator cover assembly.

Scheme 26

DRIVE LINK ASSEMBLY

Note. See COMPONENT DISASSEMBLY & REASSEMBLY for exploded views of all internal components. (Scheme 54)for thrust washer and bearing locations. (Scheme 55)for seal location and identification.

1. Remove thrust washers from sprockets. Mark position of link on drive link chain; it should be installed facing up. Pry up driven sprocket. Remove turbine shaft drive sprocket, driven sprocket and drive link chain together as an assembly. (Scheme 27)
2. Remove drive sprocket and driven sprocket supports from transaxle case. (Scheme 27)and (Scheme 28). Ensure scavenge tube seal stays in support. If not, check support for damage. Remove transaxle input speed sensor and wiring.

Scheme 27

Scheme 28

CLUTCH & BAND ASSEMBLIES

1. Remove 2nd clutch plate assembly. (Scheme 32) Remove reverse clutch support thrust washer. Remove reverse clutch housing and 2nd sprag assembly. Remove 4th band. Holding 3rd clutch housing by input shaft, remove 3rd clutch and reaction carrier assemblies. (Scheme 30) Remove reaction carrier shell.
2. Move manual control shaft from "P" position. Remove parking pawl and pivot pin assembly. Remove 2 forward and coast clutch support bolts from transaxle case. (Scheme 29) Remove oil cooler return fitting to forward and coast clutch support. CAUTION: Forward/Coast clutch assembly weighs 50 lbs., ensure appropriate lifting equipment is used.
3. Using Forward/Coast Clutch Puller (J-39053), remove clutch assemblies. (Scheme 29) Remove lo/reverse band and fretting ring.
4. Remove detent spring. Remove detent lever roller assembly. While holding detent lever in place, remove manual shaft nut. Remove detent lever and actuator rod. Discard detent lever. Remove manual shaft assembly, and case seals.

Note. If detent lever is removed, detent lever must be replaced.

Scheme 29

Reassembly

1. Using seal ring expander, install both seal rings. Using Seal Ring Sizer (J-34741-3), compress seal rings and leave tool in place until input housing is installed.
2. Apply petroleum jelly to 3rd clutch piston seals. While rotating, insert piston into 3rd clutch housing. Install spring and retainer assembly. Place retainer on top of spring and retainer assembly. Using appropriate compressor, install snap ring.
3. Install apply plate, clutch plates, starting with fiber and alternating, fiber-steel-fiber etc. (Scheme 30) Install backing plate with stepped side up. Install snap ring, thrust washer and 3rd clutch hub assembly.
4. Install thrust washer with rolled inner lip facing clutches. Install reaction sun gear and shell assembly. Install thrust bearing inside reaction carrier and install reaction carrier assembly.
5. Install reaction carrier thrust bearing with Black side facing reaction carrier. Install input sun gear and snap ring. Using petroleum jelly attach selective thrust washer and thrust bearing to top of clutch housing.

Scheme 30

LEGEND FOR (Scheme 30)

1. Install NEW seals on reverse clutch piston. Apply petroleum jelly to seals and install clutch piston into housing. Install spring and retainer assembly. Using appropriate compressor, install snap ring.
2. Install Belleville plate, steel plate and fiber plate, alternating steel, then fiber until all 6 discs are installed. Install apply plate, stepped side up and snap ring. Install 2nd clutch outer race thrust washer.
3. Install sprag clutch into outer race. Ensure 2nd sprag rotates in correct direction. With sprag assembled on top of reverse clutch and race housing, hold housing and ensure 2nd sprag race turns clockwise. (Scheme 31) Install sprag clutch retainer. Install NEW 2nd sprag spiral snap ring, if removed. Ensure spiral snap ring tabs lock into place and is fully seated.

Scheme 31

LEGEND FOR (Scheme 31)

Apply petroleum jelly to seals. To reassemble, reverse disassembly procedures.

Scheme 32

LEGEND FOR (Scheme 32)

1. Install input carrier assembly onto reaction internal gear with snap ring. Install thrust washer/bearing onto input carrier. Install input internal gear flange onto gear with snap ring. Install thrust washer onto flange.
2. Install forward clutch sprag assembly. Ensure direction of cage lip is correct. (Scheme 34) Install thrust washer onto coast clutch hub. Install coast clutch hub onto flange with snap ring. Install thrust washer/bearing onto coast clutch hub.

Scheme 33

LEGEND FOR (Scheme 33)

Scheme 34

LEGEND FOR (Scheme 34)

Install NEW seals to clutch support. Install lo roller clutch. (Scheme 35) Turn counterclockwise as far as possible. Ensure tabs on clutch rest on face of clutch support. Ensure lo roller clutch turns in correct direction and locks in opposite direction. (Scheme 36)

Scheme 35

LEGEND FOR (Scheme 35)

Scheme 36

1. Place NEW seals on forward clutch piston and install in housing. Install forward apply ring. Place NEW seals on coast clutch piston and install in housing. Install spring and retainer assembly. Using appropriate compressor, apply pressure to spring and retainer assembly and install snap ring. Install backing plate, forward clutch, Belleville, coast clutch and apply plates, in reverse order. (Scheme 33) Install clutch assembly snap ring.
2. Install thrust bearing to back side of forward/coast clutch housing. Connect forward clutch support assembled under FORWARD & COAST CLUTCH SUPPORT to forward/coast clutch housing. Assemble coast clutch hub with thrust bearing, and input internal gear and flange into forward/coast clutch housing. (Scheme 34) NOTE: When splines of coast clutch hub and forward sprag outer race are properly engaged the input carrier bushing will drop below forward/coast clutch support hub. Ensure a dull metal sound is heard during engagement.
3. Install input carrier and reaction internal gear with thrust washer onto input internal gear. Install final drive sun gear shaft. (Scheme 34)and (Scheme 35). Install thrust bearing and parking lock gear. Install snap ring.

1. Assemble differential side gears and thrust washers into carrier. Replace snap ring on right side gear output shaft. Using petroleum jelly, stick thrust washers onto pinion gears. Assemble pinion gears and washers into carrier.
2. Rotate pinion gears into position, then install pinion shaft. Tap retaining pin into position using a plastic hammer. Assemble remaining thrust washers, spacers and snap rings. Install final drive sun gear seal into sun gear with seal lip facing forward clutch. Install sun gear.

Scheme 37

LEGEND FOR (Scheme 37)

Disassembly

1. Thoroughly clean and air dry valve bodies. Remove check balls. Remove each valve train.
2. Lay valves, springs and bushings on a clean surface in the order removed. Remove solenoids, sensor, screens, servos and accumulator assemblies.

Reassemble valve body assemblies. (Scheme 38)- (Scheme 40). Using Guide Pins (J-39630-1 and J-39068-2), assemble lower valve body to channel plate. (Scheme 41)- (Scheme 43). Ensure NEW pressure control solenoid filter and oil pressure screen is used. After assembly, ensure all valves move freely in respective bores.

Note. Install oil pressure switch assembly to lower valve body. Illustration of oil pressure switch assembly is not available.

Scheme 38

LEGEND FOR (Scheme 38)

Scheme 39

Scheme 40

LEGEND FOR (Scheme 40)

Scheme 41

Scheme 42

Scheme 43

1. Clean and air dry oil pump. Remove secondary pump body from primary/scavenge pump assembly. These components are held together tightly by 2 roll pins. Remove oil pump shaft and secondary pump gears.
2. Remove scavenge pump body and gears from scavenge pump cover. Remove primary pump body and gears from scavenge oil pump cover. (Scheme 45) Remove retainer pin, ball seat and ball. Remove retainer pin, pressure regulator valve and sleeve, and boost valve assembly. (Scheme 44)

Install valve train assemblies into pump body. Install and align oil pump gears with punch marks up. Ensure oil pump shaft end with 4 notches into secondary pump. Assemble scavenge oil pump cover and secondary oil pump body to scavenge oil pump body.

Scheme 44

Scheme 45

TRANSAXLE REASSEMBLY

Note. All selective snap ring and thrust washer measurements taken during disassembly must be rechecked at appropriate reassembly stage.

Scheme 46

Scheme 47

Scheme 48

Scheme 49

Scheme 50

Scheme 51

Scheme 52

1. Install manual shaft, detent lever assembly and parking pawl, if removed. Install drive sprocket support, transaxle input speed sensor and wiring harness. (Scheme 28) Install torque converter seal.
2. Install lo/reverse band and ensure anchor engages band. Install fretting ring with open end at bottom. Install oil cooler return fitting "O" ring to coast and forward clutch assembly. Using Forward/Coast Clutch Puller (J-39053), install coast and forward clutch assembly into case. (Scheme 29) Ensure anchor holes in support align with holes in case.
3. Install final drive internal gear with groove up. Install snap ring with open end in scavenge tube area. Rotate support counterclockwise against spline. (Scheme 46)
4. Install reaction shell and 3rd clutch housing. Install input shaft selective washer and thrust bearing on 3rd clutch housing. see scheme 13 Install 4th band and reverse clutch assembly. (Scheme 47) Ensure band pin seat engages servo pin. Install reverse clutch housing and thrust washer.
5. Install seal on drive sprocket support. Using Sizer (J-39064-2), size seal. Install backing plate, 2nd clutch plates, apply plate and waved plate.
6. Place scavenge tube seal on driven sprocket support and install driven sprocket support. Install drive chain (in same direction as removed) to drive sprocket support. Tap sprockets until seated. Place thrust roller bearings on sprockets.
7. To air check reverse, 2nd and 3rd clutches at drive sprocket support, go to next step. Install island gasket and case cover gasket. Install case cover allowing wiring harness connector to pass through opening in case cover. Install bolts in correct position and hand tighten only. (Scheme 49) Go to step 10).
8. Using 40 psi (2.7 kg/cm 2 ) of air pressure, air check clutches and servos. Reverse, 2nd and 3rd clutches may be checked at driven sprocket support. Coast and forward clutches may be checked through passage in lower case. (Scheme 50) To check Reverse clutch, 3rd clutch or 4th servo, fabricate an air checking plate. (Scheme 51)
9. Trace template as shown. (Scheme 51) Using 3/8-1/2" thick aluminum or plastic plate, cut out an air checking plate to match template. Mark and drill holes in plate. Drill bolt holes.275" (7 mm) and air holes.157" (4 mm). Bolt plate to case. Air check clutches and 4th servo. NOTE: About 90-100 psi (6.2-6.9 kg/cm 2 ) of air pressure are required to apply the 3rd clutch.
10. Check input shaft end play. see scheme 13 Install Input Shaft End Play Fixture (J-39686) to front side of transaxle. Ensure "J" tab on fixture rests on input shaft. Mount Dial Indicator Post (J-25025-7A) and Dial Gauge (J-8001-3) to check end play. Push down on handle. End play should be.004-.034" (.10-.85 mm). Input shaft thrust washers size range is.089-.195" (2.27-4.97 mm) in increments of.012" (.30 mm).
11. Tighten case cover bolts and studs in a criss-cross pattern. Install 2 check balls. (Scheme 49) Install upper valve body. (Scheme 52) Tighten bolts starting with center ones and working to outside ones. Install side filter.
12. Install TCC/VCC solenoid and transaxle pressure control solenoid. Install oil pump assembly. Tighten bolts starting with center ones and working to outside ones. Install oil pan and tighten bolts in a star pattern. Install 4th servo. (Scheme 48) Ensure tab on servo piston aligns with slot in case (some models).
13. Using a long thin piece of.025" (.60 mm) shim stock, slide lo/reverse band into position. Install lower valve body and channel plate. (Scheme 53) Install bolts and tighten by hand. Remove shim stock.
14. Install oil transfer plate and hand tighten bolts. (Scheme 53) Connect wiring harness and manual valve. Tighten channel plate and oil transfer plate bolts in a criss-cross pattern. Install scavenge screens. (Scheme 48) Install pan gasket and tighten bolts in a star pattern.
15. Assemble and install final carrier, output shaft and differential carrier. (Scheme 48) Engage parking pawl to hold final drive unit. Tighten differential carrier bolts.
16. Install scavenge tube and seal. Install selective thrust washer and roller thrust bearing onto output shaft. (Scheme 48) Install extension housing and hand tighten bolts.
17. Mount Dial Indicator Post (J-39687) and Dial Gauge (J-8001-3) to check end play. Pry up on speed sensor rotor through speed sensor hole. End play should be.006-.025" (.15-.65 mm). (Scheme 25)
18. If necessary, adjust end play with selective final drive-to-case thrust washer. See «FINAL DRIVE-TO-CASE SELECTIVE THRUST WASHER SIZES»(ref-25525-S27895747382001011700000). Tighten extension housing bolts. Install oil cooler return fitting to forward and coast clutch support. Install axle seals, oil pump drive shaft, torque converter and vehicle speed sensor.

FINAL DRIVE-TO-CASE SELECTIVE THRUST WASHER SIZES

Scheme 53

Scheme 54

LEGEND FOR (Scheme 54)

Scheme 55

LEGEND FOR (Scheme 55)