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

GEAR RATIOS

TRANSAXLE GEAR RATIOS

TRANSAXLE CASE

Remove torque converter, turbine shaft "O" ring, oil pump drive shaft, vehicle 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.

INPUT SHAFT END PLAY CHECK

Install Input Shaft End Play Fixture (J-39686) to front side of transaxle. Ensure "J" tab on fixture rests on input shaft. Arrow on tab should have a 90 degree orientation. Washer must rest flat on case cover seal. Rotate threaded shaft clockwise until shaft is tight. Leave enough space for collar. Insert collar. Mount Dial Indicator Post (J-25025-7A) and Dial Indicator (J-8001-3) to check end play. Push down on handle to raise input shaft. End play should be.004-.033" (.10-.85 mm). (Scheme 39) Record this measurement for reassembly.

Scheme 39

SIDE COVER, OIL PUMP & UPPER VALVE BODY

1. Remove side cover, filter and seals. Disconnect wiring harness from fluid temperature sensor, pressure control solenoid, TCC solenoid and case connector. Remove wiring harness.
2. Remove oil pump assembly cover bolts. see scheme 37 Remove pump assemblies. Remove upper valve body and separate gasket and spacer plate. Remove 2 check balls between spacer plate and case cover. Remove case cover and gaskets from transaxle case.

DRIVE LINK

Note. See COMPONENT DISASSEMBLY & REASSEMBLY for exploded views of all internal components. For thrust washer, thrust bearing and seal locations, refer to appropriate illustration. see scheme 40or see scheme 41.

1. Remove thrust washers from sprockets. Grasp drive link chain above drive sprocket and pull toward transaxle case. Measure drive link chain-to-case clearance. If clearance is less than.50" (12.7 mm), replace drive link chain.
2. Mark position of drive link chain for reassembly reference. Noise may occur if chain is not installed in same direction as removed. Pry up driven sprocket. If necessary, tap on end of turbine shaft using plastic hammer. Remove turbine shaft and drive sprocket, driven sprocket and drive link chain together as an assembly. (Scheme 40)
3. Remove drive sprocket and driven sprocket supports from transaxle case. (Scheme 41) Ensure scavenge tube seal remains in support. If not, check support for damage. Remove input speed sensor and wiring harness.

Scheme 40

Scheme 41

LOW-REVERSE SERVO & 4TH SERVO

For low-reverse servo disassembly procedure. See VALVE BODIES . For 4th servo disassembly procedure, see TRANSAXLE CASE under TRANSAXLE DISASSEMBLY.