Complete procedure for replacing the transmission input shaft bearing on a 1966 Chevrolet Corvette with 327ci V8, requiring transmission removal and disassembly.

Warnings

Tools required

Parts

• Transmission input shaft bearing × 1 — Use OEM specification
• Transmission front bearing retainer seal × 1 — Use OEM specification
• Transmission pan gasket × 1 — Use OEM specification
• Transmission to bellhousing gasket × 1 — Use OEM specification
• Input shaft snap ring × 1 — Typically included with bearing
• Rear transmission mount × 1 — Inspect and replace if damaged

Fluids

• Dexron III ATF — 11.5 qt

Preparation

1. Park vehicle on level surface and set parking brake.
2. Disconnect negative battery cable to prevent accidental starter engagement.
3. Raise vehicle and support securely on jack stands at frame rails.
4. Allow transmission to cool completely if vehicle was recently operated.
5. Place drain pans under transmission pan and rear of transmission.
6. Remove transmission dipstick from tube to vent during fluid drain.

Procedure

1. 1

   Drain transmission fluid
   Remove the transmission pan bolts and carefully lower the pan to drain fluid into the drain pan. Some fluid will remain in the torque converter. Remove and discard the old pan gasket, then clean the pan and mating surface on the transmission case thoroughly.
2. 2

   Disconnect driveshaft
   Mark the driveshaft yoke and differential flange with alignment marks using a paint pen. Remove the 4 U-joint strap bolts at the rear differential. Slide the driveshaft rearward to disengage from the transmission output shaft, then lower and remove from vehicle. Install a plug or tape over the transmission extension housing to prevent fluid leakage.
3. 3

   Disconnect shift linkage and electrical connections
   Disconnect the shift linkage rod or cable from the transmission shift lever. Disconnect the neutral safety switch electrical connector and any other transmission electrical connections. On vacuum modulator equipped transmissions, disconnect the vacuum line from the modulator.
4. 4

   Disconnect transmission cooler lines
   Using a flare nut wrench, disconnect the 2 transmission cooler lines from the transmission case fittings. Cap or plug the lines and transmission ports immediately to prevent fluid loss and contamination. Have a drain pan ready as residual fluid will drain from the lines.
5. 5

   Support engine and remove transmission crossmember
   Position a floor jack with a block of wood under the engine oil pan to support engine weight. Remove the 2 bolts securing the transmission mount to the crossmember, then remove the 4 bolts securing the crossmember to the frame. Remove the crossmember from the vehicle.
6. 6

   Remove bellhousing access cover and torque converter bolts
   Remove the bellhousing lower inspection cover (2-3 bolts). Rotate the engine crankshaft using a socket on the front harmonic balancer bolt to access each of the 3 torque converter-to-flexplate bolts through the inspection opening. Remove all 3 bolts. Mark the converter-to-flexplate relationship before removing the last bolt.
7. 7

   Remove transmission-to-bellhousing bolts
   Position the transmission jack under the transmission pan and secure with the jack safety chain. Remove the 6 bolts securing the transmission case to the engine bellhousing. Note the location of any wiring harness clips or ground straps attached to these bolts.
8. 8

   Remove transmission from vehicle
   With the transmission fully supported on the jack, carefully slide the transmission rearward to disengage the input shaft from the torque converter pilot. Keep the transmission level to prevent the torque converter from sliding out. Once clear of the engine, lower the transmission jack and remove the transmission from under the vehicle. Secure the torque converter to the transmission case with a retaining strap or wire to prevent it from falling out during handling.
9. 9

   Remove torque converter and front pump
   Place the transmission on a secure workbench with the front facing up. Remove the torque converter by sliding it straight out of the transmission. Remove the 8 bolts securing the front pump (bearing retainer) to the transmission case. Carefully pry the pump assembly out of the case using a pry bar, working around the perimeter evenly.
10. 10

    Remove input shaft assembly
    With the front pump removed, the input shaft assembly (forward clutch drum, forward clutch pack, and input shaft) is now accessible. Lift the entire forward clutch and input shaft assembly straight up and out of the transmission case. Place on a clean workbench.
11. 11

    Disassemble input shaft bearing
    Using snap ring pliers, remove the internal snap ring that retains the input shaft bearing in the front pump housing. Using a bearing puller, carefully extract the old bearing from the pump housing bore. Inspect the pump housing bore for scoring or damage. Clean the bore thoroughly with solvent and allow to dry.
12. 12

    Inspect input shaft and measure dimensions
    Clean the input shaft bearing surface thoroughly. Using a micrometer, measure the shaft diameter at the bearing journal to verify it meets specification (typically 0.001-0.002 inch wear limit). Inspect for scoring, discoloration from heat, or excessive wear. Replace the input shaft if measurements are out of specification or if damage is present.
13. 13

    Install new input shaft bearing
    Place the new bearing squarely into the front pump housing bore with the numbered side facing out (visible side). Using a bearing driver of appropriate diameter or an arbor press, drive the bearing straight into the housing until it seats completely against the internal shoulder. Install the snap ring to retain the bearing, ensuring it is fully seated in the groove. Verify bearing rotates smoothly by hand.
14. 14

    Replace front pump seal and reassemble pump
    Using a seal removal tool or screwdriver, carefully pry out the old front seal from the pump housing. Clean the seal bore and install the new seal using a seal driver, ensuring it is seated flush with the housing face. Lubricate the seal lip with clean ATF before installation.
15. 15

    Reassemble transmission and install in vehicle
    Reinstall the input shaft and forward clutch assembly into the transmission case. Install the front pump assembly with a new gasket, ensuring proper alignment of the pump gears with the input shaft. Install the 8 pump retaining bolts and tighten in a star pattern to prevent warping. Install the torque converter into the front pump, ensuring it engages fully with all driving surfaces (stator support splines, input shaft splines, and front pump drive). Rotate the converter while pushing inward until you feel it drop through each engagement step, then verify the converter is fully seated and recessed below the bellhousing mounting surface per the Powerglide service specification. Reverse steps 1-8 to reinstall the transmission in the vehicle.

Reassembly

1. Torque all bellhousing-to-transmission bolts, torque converter-to-flexplate bolts, and crossmember bolts to factory specification (torque specifications should be verified from a factory service manual).
2. Ensure the torque converter is fully seated before mating transmission to engine - converter lugs must engage stator support, input shaft, and pump drive.
3. Reconnect all electrical connectors, shift linkage, and vacuum lines in reverse order of removal.
4. Install new transmission pan gasket and refill transmission with 11.5 quarts of Dexron III ATF through the dipstick tube.
5. Reconnect negative battery cable.

Verification

• With engine running and parking brake set, cycle through all gear positions and verify smooth engagement.
• Check for fluid leaks at the pan gasket, cooler lines, front pump seal, and all other connection points.
• Road test vehicle through all gears to verify proper shifting and absence of abnormal noise from the input shaft bearing area.
• Recheck transmission fluid level at operating temperature with engine idling in Park, and adjust as necessary.
• Listen for bearing noise in all gear ranges - a properly installed bearing should be silent during operation.

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