Throw-Out Bearing

Replace the throw-out bearing (clutch release bearing) in a 1966 Chevrolet Corvette with 327ci V8, requiring transmission removal to access the clutch assembly.

Warnings

Tools required

Parts

• Throw-out bearing (clutch release bearing) × 1 — Use OEM specification
• Transmission input shaft seal × 1 — Use OEM specification
• Clutch fork boot × 1 — Use OEM specification
• Pilot bearing (if worn) × 1 — Use OEM specification
• High-temp clutch bearing grease × 1 — Use OEM specification

Preparation

1. Park vehicle on level, solid ground and set parking brake firmly
2. Place wheel chocks behind front wheels
3. Disconnect negative battery cable
4. Allow exhaust system to cool completely if vehicle was recently operated
5. Raise vehicle and support securely on jack stands at frame rails, providing adequate clearance for transmission removal
6. Remove exhaust system from manifolds back to provide clearance for transmission removal

Procedure

1. 1

   Mark and remove driveshaft
   Using a marker or paint pen, mark the relationship between the rear U-joint yoke and the differential pinion flange to ensure correct phasing on reassembly. Remove the 2 U-bolts (straps) securing the rear U-joint to the differential pinion flange. Support the driveshaft, remove the front U-joint fasteners at the transmission output yoke, and lower the driveshaft from the vehicle. Note that the 1966 Corvette uses a fixed-length driveshaft with U-joints at both ends (no slip yoke into the transmission).
2. 2

   Disconnect shift linkage and electrical connections
   Disconnect the shift lever linkage from the transmission side cover. For 4-speed manual transmissions, remove the shift lever boot inside the car and unbolt the shifter mechanism from the transmission (4 bolts). Tag and disconnect the backup light switch wire from the transmission case.
3. 3

   Disconnect speedometer cable and clutch linkage
   Unscrew the speedometer cable from the transmission extension housing (verify side; typically passenger side on the Muncie 4-speed). Disconnect the clutch fork return spring. Disconnect the clutch linkage pushrod from the clutch fork by removing the clevis pin and retaining clip.
4. 4

   Support transmission and remove crossmember
   Position a transmission jack or equivalent support under the transmission pan. Apply slight upward pressure to take the weight off the crossmember. Remove the 2 bolts securing the transmission mount to the crossmember. Remove the 4 bolts securing the crossmember to the frame and remove the crossmember from the vehicle.
5. 5

   Remove bellhousing bolts
   Remove the bellhousing-to-engine block bolts. There are 6 bolts securing the bellhousing to the engine block. Note the location of any ground straps or brackets attached to these bolts for proper reassembly.
6. 6

   Remove transmission assembly
   With an assistant or using proper transmission jack positioning, carefully slide the transmission rearward, keeping it level and aligned with the input shaft. The input shaft must clear the clutch disc splines and pilot bearing without binding. Once clear of the clutch assembly, lower the transmission and remove it from under the vehicle. Be careful not to let the weight of the transmission hang on the input shaft during removal.
7. 7

   Remove throw-out bearing and clutch fork
   Slide the throw-out bearing forward off the transmission input shaft bearing retainer. Unhook the clutch fork from the ball stud pivot inside the bellhousing by prying the fork retaining spring away from the ball stud. Remove the clutch fork through the side opening in the bellhousing. Remove and discard the old clutch fork boot.
8. 8

   Inspect clutch assembly and related components
   With the throw-out bearing removed, inspect the clutch pressure plate fingers for wear or heat discoloration. Check the clutch disc for oil contamination, glazing, or excessive wear. Inspect the pilot bearing in the crankshaft for roughness or noise by spinning it with a finger. Check the transmission input shaft for wear grooves or damage. Inspect the clutch fork for cracks or excessive wear at the pivot ball and bearing contact points. Replace any worn components as necessary.
9. 9

   Install new throw-out bearing
   Apply a light coating of high-temp clutch bearing grease to the transmission input shaft bearing retainer where the throw-out bearing slides. Do NOT pack the bearing itself with grease unless it is a specific sealed bearing that requires it (most throw-out bearings are pre-lubricated). Slide the new throw-out bearing onto the input shaft bearing retainer with the spring fingers or actuating mechanism facing toward the clutch pressure plate.
10. 10

    Install clutch fork and boot
    Apply a small amount of high-temp grease to the ball stud pivot point and to the clutch fork ends where they contact the throw-out bearing. Insert the clutch fork through the bellhousing side opening and engage it onto the ball stud pivot, ensuring the retaining spring clips securely over the ball stud. Hook the clutch fork fingers into the throw-out bearing grooves. Install the new clutch fork boot over the bellhousing opening.
11. 11

    Clean and prepare transmission input shaft
    Clean the transmission input shaft splines thoroughly with brake cleaner and a wire brush. Apply a thin coating of high-temp grease to the input shaft splines. Replace the transmission input shaft seal if it shows any signs of leakage or wear.
12. 12

    Install transmission assembly
    With an assistant or using a transmission jack, raise the transmission into position behind the engine. Insert a clutch alignment tool through the clutch disc and into the pilot bearing to ensure proper alignment. Carefully guide the transmission input shaft through the throw-out bearing and into the clutch disc splines, keeping the transmission level and aligned. Do not force the transmission; if it does not slide forward easily, the input shaft may not be aligned with the clutch disc splines. Once the bellhousing is flush against the engine block, install the 6 bellhousing-to-engine bolts finger-tight, then torque in a cross pattern.
13. 13

    Install crossmember and secure transmission mount
    Position the crossmember into place and install the 4 frame mounting bolts. Install the 2 transmission mount-to-crossmember bolts. Remove the transmission jack support.
14. 14

    Reconnect clutch linkage, speedometer, and electrical connections
    Reconnect the clutch linkage pushrod to the clutch fork using the clevis pin and retaining clip. Install the clutch fork return spring. Connect the speedometer cable to the transmission. Reconnect the backup light switch wire.
15. 15

    Reconnect shift linkage and install driveshaft
    Reconnect the shift linkage to the transmission (or reinstall the shifter mechanism inside the car if removed). Align the marks made during disassembly and install the driveshaft, sliding the slip yoke into the transmission tailshaft. Connect the rear U-joint to the differential pinion flange using the 4 U-bolts.
16. 16

    Reinstall exhaust system and finalize
    Reinstall the exhaust system from the manifolds back, ensuring all hangers and clamps are properly secured. Reconnect the negative battery cable. Lower the vehicle from jack stands.

Reassembly

1. Torque all fasteners to manufacturer specifications when available
2. Ensure all transmission bellhousing bolts are torqued in a cross pattern to prevent distortion
3. Verify driveshaft U-joint phasing marks are aligned to prevent driveline vibration
4. Check that all electrical connections and ground straps are properly secured
5. Verify clutch fork return spring is properly installed and clutch pedal has proper free play

Verification

• Start the engine and verify the clutch pedal operates smoothly with proper free play (approximately 1 inch at the pedal)
• With the engine running, depress the clutch pedal and shift through all gears to verify smooth engagement
• Test drive the vehicle and verify smooth clutch operation without slipping, chatter, or abnormal noises
• Listen for any grinding or bearing noise when depressing the clutch pedal, which would indicate improper throw-out bearing installation
• Check for any fluid leaks around the transmission input shaft seal after test drive
• Verify no driveline vibration is present at various speeds, confirming proper driveshaft phasing

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