Complete disassembly, inspection, rebuild and reinstallation of the U660E/U661E automatic transmission including replacement of wear components, seals, and gaskets.

Warnings

Tools required

Parts

• Transmission rebuild kit with clutches, steels, and seals × 1 — U660E/U661E overhaul kit - Use OEM specification
• Transmission filter kit × 1 — 35330-02060 or equivalent
• Transmission pan gasket × 1 — 35168-12040 or equivalent
• Torque converter seal × 1 — Use OEM specification
• Output shaft seal × 1 — Use OEM specification
• Input shaft seal × 1 — Use OEM specification
• Thrust washers and bearings × 1 — Included in rebuild kit
• Snap rings (assorted) × 1 — Included in rebuild kit
• Transmission drain plug crush washer × 1 — 90430-12031 or equivalent
• Engine/transmission mounting bolts × 1 — Use OEM specification if damaged

Fluids

• Toyota WS ATF — 10 qt

Preparation

1. Park vehicle on level surface and engage parking brake
2. Disconnect negative battery cable and secure away from terminal
3. Raise vehicle and support securely on jack stands at all four corners
4. Remove front wheels for access to axle nuts and subframe
5. Drain transmission fluid by removing drain plug, allow 20 minutes for complete drainage
6. Remove engine under covers and splash shields for access
7. Place transmission jack under transmission pan for support
8. Set up clean assembly area with parts trays labeled for each section (valve body, gear train, clutch packs, etc.)
9. Review rebuild kit instructions and verify all parts are present before beginning disassembly

Procedure

1. 1

   Remove transmission from vehicle
   Disconnect shift cable, electrical connectors, and cooler lines from transmission. Remove starter motor. Support engine with jack or support fixture. Remove front axle shafts by removing axle nuts and separating ball joints. Remove transmission mounting bolts noting location of different lengths. Carefully lower transmission on transmission jack, ensuring torque converter stays with transmission. Once clear of vehicle, remove torque converter and store upright to prevent fluid loss.
2. 2

   External cleaning and inspection
   Thoroughly clean exterior of transmission with degreaser and compressed air. Inspect case for cracks, stripped threads, or damage. Check cooler line fittings for damage. Inspect electrical connectors for corrosion. Mount transmission securely on work bench with torque converter opening facing up.
3. 3

   Remove valve body assembly
   Remove transmission pan bolts in criss-cross pattern and lower pan. Remove and inspect filter for metal particles or debris. Remove valve body cover screws and carefully lower valve body assembly keeping solenoids attached. Keep all bolts organized by location as they are different lengths. Inspect valve body separator plate and gaskets for damage or wear patterns.
   Torque spec

   Pan Bolts15 Nm (11 lb-ft)

   Cover Screws10 Nm (8 lb-ft)
4. 4

   Disassemble valve body
   On clean bench, remove solenoid bolts and carefully extract each solenoid. Label position of each solenoid as they are not interchangeable. Disassemble valve body sections, keeping check balls, springs, and valves organized by circuit. Inspect all valves for scoring, wear, or sticking. Clean all passages with compressed air and ATF. Replace any worn valves per rebuild kit instructions.
   Torque spec

   Sensor Bolts10 Nm (8 lb-ft)
5. 5

   Remove and disassemble pump assembly
   Remove pump mounting bolts from front of case. Carefully extract pump assembly straight out to avoid damage to bushing or case. Disassemble pump by removing pump cover bolts. Inspect pump gears, crescent, and body for scoring or wear. Measure pump body clearances with feeler gauge. Replace pump components as needed per rebuild kit specifications. Inspect stator support shaft for wear.
   Torque spec

   Mounting Bolts58 Nm (43 lb-ft)
6. 6

   Remove clutch pack assemblies
   Remove large snap ring retaining forward clutch assembly. Carefully lift out forward clutch pack. Remove center support snap ring and extract direct clutch assembly. Label and organize clutch plates and steels in order of removal. Use spring compressor tool to compress clutch return springs and remove snap rings. Extract pistons carefully to avoid damaging seals. Inspect clutch plates for burning, glazing, or excessive wear. Measure clutch plate thickness and steel plate flatness.
7. 7

   Remove planetary gear sets
   Remove snap rings retaining planetary gear assemblies. Carefully lift out front and rear planetary gear sets, keeping thrust washers with their respective assemblies. Inspect planetary gears for broken teeth, excessive wear, or damage. Check pinion gear end play with dial indicator. Inspect sun gear splines and surfaces. Replace planetary assemblies if any damage is found as they are not serviceable individually.
8. 8

   Disassemble case and inspect internal components
   Remove all remaining snap rings, thrust washers, and bearings from case. Extract any remaining shafts or components. Inspect all case bushings for wear or scoring. Check case bearing bores for damage. Inspect case oil passages for blockage or damage. Measure all thrust washer thicknesses and record for proper selective assembly. Clean case thoroughly with compressed air and lint-free cloths.
9. 9

   Install new seals and bearings
   Using seal driver set, carefully install new input shaft seal, output shaft seal, and case seals from rebuild kit. Install new bushings if case bushings show wear. Install new bearing races using race driver ensuring they are fully seated. Lubricate all new seals with ATF before installation. Install new thrust bearings and washers in proper locations using assembly lubricant to hold in place.
10. 10

    Rebuild clutch pack assemblies
    Install new inner and outer seals on clutch pistons using seal installation tools. Lubricate pistons and bores with ATF. Carefully install pistons into drums ensuring seals do not roll or tear. Install new return springs and compress with spring compressor tool. Install new snap rings. Soak new clutch plates in ATF for 30 minutes before installation. Install clutch packs alternating plates and steels per rebuild kit specifications. Install waved snap ring or backing plate. Measure clutch pack clearance with feeler gauge and verify within specification (typically 0.8-1.5mm depending on pack).
11. 11

    Reassemble gear train into case
    Install output shaft into case with new thrust washers. Install rear planetary assembly with proper thrust bearing. Install center support with new seals and snap ring. Install direct clutch assembly ensuring proper engagement. Install front planetary with thrust washers. Install forward clutch assembly checking for proper engagement with planetary. Install all selective snap rings ensuring full engagement in grooves. Check end play of each assembly with dial indicator and verify within specifications.
12. 12

    Install pump assembly
    Reassemble pump with new components from rebuild kit. Install new pump seal and O-rings. Lubricate pump assembly with ATF. Install new pump gasket or O-ring on case. Carefully align and install pump assembly into case ensuring proper engagement with gear train. Rotate pump to verify free rotation. Install pump mounting bolts and torque to specification.
    Torque spec

    Mounting Bolts58 Nm (43 lb-ft)
13. 13

    Reassemble and install valve body
    Reassemble valve body with new springs, check balls, and components per rebuild kit instructions. Verify all valves move freely. Install new solenoids or clean and test existing solenoids. Install new valve body gaskets and separator plate. Position valve body onto case ensuring all manual valve and park pawl linkages engage properly. Install valve body cover screws and torque to specification in criss-cross pattern. Install new filter and O-ring.
    Torque spec

    Cover Screws10 Nm (8 lb-ft)

    Sensor Bolts10 Nm (8 lb-ft)
14. 14

    Install transmission pan and prepare for installation
    Clean pan thoroughly and install new gasket or apply RTV sealant per manufacturer specifications. Install pan and torque pan bolts in criss-cross pattern to specification. Install new drain plug with new crush washer and torque to specification. Inspect torque converter for damage, worn bushing, or contamination. Install new torque converter seal in pump. Install torque converter onto transmission input shaft ensuring full engagement (should click into place at least twice). Verify torque converter is fully seated by measuring depth from bellhousing mounting surface to torque converter lug (should be approximately 18-20mm).
    Torque spec

    Pan Bolts15 Nm (11 lb-ft)

    Transmission Drain Plug30 Nm (22 lb-ft)
15. 15

    Install transmission and connect components
    Support transmission on transmission jack and carefully raise into position. Ensure torque converter stays engaged during installation. Align transmission to engine and install mounting bolts finger tight initially. Torque transmission to engine mounting bolts to proper specifications starting with upper bolts. Install axle shafts and torque axle nuts. Install starter motor. Reconnect cooler lines, electrical connectors, and shift cable. Verify all connections are secure. Install transmission brace/mount and torque to specification. Lower vehicle and fill transmission with proper amount of Toyota WS ATF through dipstick tube or fill plug.
    Torque spec

    Mounting Bolts58 Nm (43 lb-ft)

    Flywheel Bolts95 Nm (70 lb-ft)

Reassembly

1. Ensure all snap rings are fully seated in grooves and not twisted
2. Verify all thrust washers and bearings are in correct positions per service manual diagram
3. Double check all clutch pack clearances are within specification before buttoning up transmission
4. Ensure valve body manual valve aligns with manual shaft before tightening valve body bolts
5. Verify torque converter is fully engaged before final transmission installation - should spin freely and be recessed properly
6. Use new gaskets, seals, and O-rings throughout - do not reuse old seals
7. Fill transmission to proper level using only Toyota WS ATF specification fluid

Verification

• With engine running and parking brake set, verify smooth engagement into all gear positions (P, R, N, D, S, L)
• Check for fluid leaks around pan, cooler lines, seals, and case mating surfaces
• Perform transmission relearn procedure using Toyota Techstream or equivalent scan tool
• Test drive vehicle and verify smooth shifts under light and moderate acceleration with no slipping, harsh engagement, or delayed shifts
• Check transmission fluid level at operating temperature (160-180°F) with engine running in Park on level ground
• Monitor transmission temperature during test drive to ensure proper cooling system operation
• Recheck fluid level after test drive and top off if necessary
• Scan for any transmission-related diagnostic trouble codes and address if present

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