This procedure covers removal and replacement of the flexplate (flywheel for automatic transmission) on a 1966 Chevrolet Corvette with 327ci V8 and automatic transmission, requiring transmission removal for access.

Warnings

Tools required

Parts

• Flexplate (automatic transmission) × 1 — Use OEM specification for 327ci with automatic
• Flexplate-to-crankshaft bolts × 1 — Use OEM specification
• Flexplate-to-torque-converter bolts × 1 — Use OEM specification
• Transmission pan gasket × 1 — Use OEM specification for Powerglide or TH350/400
• Rear engine seal × 1 — Use OEM specification (optional replacement)

Fluids

• Dexron III ATF — 11.5 qt

Preparation

1. Park vehicle on level surface and engage parking brake
2. Disconnect negative battery cable
3. Allow engine and exhaust system to cool completely if recently operated
4. Raise vehicle and support securely on jack stands at frame rails
5. Remove both rear wheels for improved access to exhaust and transmission crossmember
6. Place drain pan under transmission pan

Procedure

1. 1

   Drain transmission fluid
   Remove the transmission pan bolts gradually, starting from one corner, allowing fluid to drain into the pan. Once drained, remove the pan completely and set aside with the old gasket. Expect approximately 4-5 quarts to drain from the pan; remaining fluid will drain during transmission removal.
2. 2

   Disconnect exhaust system
   Disconnect the exhaust system at the flange connection behind the transmission. On 1966 Corvette, this is typically a ball-flange connection at the intermediate pipe. Remove the 2 bolts at the flange and support the exhaust system with wire or a stand to prevent damage.
3. 3

   Mark and remove driveshaft
   Using a marker or paint pen, mark the relationship between the driveshaft yoke and the rear differential pinion flange for correct reassembly phasing. Remove the 4 U-joint strap bolts at the rear axle. Slide the driveshaft rearward to disengage from the transmission output shaft and remove from vehicle. Plug the transmission output shaft with a rag to prevent fluid loss.
4. 4

   Disconnect transmission linkages and wiring
   Disconnect the transmission shifter linkage at the transmission lever. Disconnect the kickdown cable or rod if equipped. Disconnect the neutral safety switch electrical connector and any other transmission wiring. On vacuum-modulated transmissions, disconnect the vacuum line from the modulator.
5. 5

   Disconnect transmission cooler lines
   Using a flare nut wrench, disconnect the two transmission cooler lines from the fittings on the right side of the transmission. Be prepared for additional fluid loss. Cap or plug the lines and fittings to prevent contamination.
6. 6

   Remove transmission crossmember
   Support the transmission with a transmission jack positioned under the pan. Remove the 2 bolts securing the transmission mount to the crossmember. Remove the 4 bolts securing the crossmember to the frame rails (2 per side) and remove the crossmember from the vehicle.
7. 7

   Remove bellhousing-to-engine bolts
   Remove the bellhousing inspection cover from the lower portion of the bellhousing to access the flexplate and torque converter. Remove all bellhousing-to-engine block bolts. On the 327ci V8, there are typically 6 bolts securing the bellhousing to the engine block. Access the upper bolts using extensions and universal joints as needed.
8. 8

   Mark and remove torque converter bolts
   Mark the relationship between the flexplate and torque converter with a paint pen for reassembly reference. Rotate the crankshaft using a breaker bar on the front crankshaft bolt to access each torque converter-to-flexplate bolt through the inspection opening. Remove all 3 bolts securing the torque converter to the flexplate. Push the torque converter back into the transmission bellhousing and secure with a strap or wire to prevent it from sliding out during transmission removal.
9. 9

   Remove transmission assembly
   With the transmission securely supported on the transmission jack, carefully slide the transmission rearward away from the engine. Ensure the torque converter remains fully seated in the transmission pump as you withdraw the assembly. Once clear of the engine, lower the transmission and move it away from the work area. The flexplate is now fully accessible.
10. 10

    Remove flexplate from crankshaft
    Using a flywheel holding tool or large pry bar wedged between the flexplate and engine block, prevent the crankshaft from rotating. Remove the 6 bolts securing the flexplate to the crankshaft flange. Remove the flexplate from the crankshaft. Inspect the crankshaft flange and rear main seal for damage or leaks.
11. 11

    Inspect and prepare new flexplate
    Inspect the crankshaft flange surface for burrs, damage, or debris and clean thoroughly with solvent and a clean rag. Inspect the pilot bearing or bushing in the center of the crankshaft for wear (some applications). Compare the new flexplate to the old unit to verify correct ring gear tooth count and bolt pattern. If the rear main seal shows any signs of leakage, now is the ideal time to replace it.
12. 12

    Install new flexplate
    Position the new flexplate onto the crankshaft flange, ensuring proper orientation (the torque converter mounting surface faces the transmission). Note that the flexplate is not symmetrical; the mounting bolt holes are offset to ensure correct installation in only one position. Install all 6 flexplate-to-crankshaft bolts finger-tight. Using the flywheel holding tool, torque the bolts in a star pattern to the manufacturer specification (typically 60-65 ft-lbs for 327ci applications, but verify).
13. 13

    Reinstall transmission assembly
    Ensure the torque converter is fully seated in the transmission pump (it should engage three distinct times as the pump drive gear, turbine shaft, and stator support engage). The converter should be recessed approximately 1/2 inch from the bellhousing face. Position the transmission on the jack and carefully align with the engine, ensuring the torque converter hub engages the crankshaft pilot. Slide the transmission forward until the bellhousing contacts the engine block evenly.
14. 14

    Install bellhousing bolts and reconnect torque converter
    Install all 6 bellhousing-to-engine block bolts and torque in a cross pattern to manufacturer specification (typically 30-35 ft-lbs). Align the marks made earlier and rotate the crankshaft to access each torque converter bolt hole through the inspection cover. Install the 3 torque converter-to-flexplate bolts and torque to specification (typically 30-35 ft-lbs). Reinstall the bellhousing inspection cover.
15. 15

    Reinstall crossmember and reconnect components
    Raise the transmission into position and install the transmission crossmember, securing it to the frame rails with the 4 bolts. Install the 2 transmission mount-to-crossmember bolts and torque all fasteners to specification. Remove the transmission jack. Reconnect the transmission cooler lines, shifter linkage, kickdown linkage, neutral safety switch, and vacuum modulator line (if equipped).
16. 16

    Reinstall driveshaft and exhaust
    Align the marks made during disassembly and slide the driveshaft forward onto the transmission output shaft. Align the rear yoke with the differential flange and install the 4 U-joint strap bolts, torquing to specification (typically 15-20 ft-lbs). Reconnect the exhaust system at the flange connection and torque the 2 flange bolts to specification.
17. 17

    Install new transmission pan gasket and refill fluid
    Clean the transmission pan and transmission case mating surface thoroughly. Install a new gasket on the transmission pan and reinstall the pan, torquing the bolts in a cross pattern to specification (typically 12-15 ft-lbs). Using a funnel in the transmission dipstick tube, add approximately 6 quarts of Dexron III ATF initially. Start the engine and allow to idle, then add fluid gradually while checking the level with the dipstick until the full mark is reached with the engine running and transmission at operating temperature.

Reassembly

1. Reinstall rear wheels and torque lug nuts to specification
2. Lower vehicle from jack stands
3. Reconnect negative battery cable
4. Check transmission fluid level with engine running at operating temperature and adjust as necessary
5. Cycle transmission through all gears while stationary to verify proper shifter operation

Verification

• Start engine and verify no abnormal noises from bellhousing area
• Check for transmission fluid leaks around pan gasket, cooler lines, and output shaft
• With parking brake firmly applied, verify transmission engages in all gear positions
• Road test vehicle to verify smooth acceleration with no vibration or unusual noise from driveline
• Recheck transmission fluid level after road test and adjust if necessary
• Verify no check engine light or transmission-related fault codes

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