Clutch Slave Cylinder

Remove and replace the hydraulic clutch slave cylinder on a 1966 Chevrolet Corvette with 327ci V8 engine, including bleeding the hydraulic clutch system.

Warnings

Tools required

Parts

• Clutch slave cylinder × 1 — Use OEM specification
• Slave cylinder mounting gasket or seal (if equipped) × 1 — Use OEM specification

Fluids

• DOT 4 Brake Fluid — 0.25 qt

Preparation

1. Park vehicle on level ground and apply parking brake
2. Place wheel chocks behind rear wheels
3. Raise front of vehicle with floor jack and support securely on jack stands
4. Allow engine and exhaust system to cool completely if recently driven
5. Locate the clutch slave cylinder on the driver side of the bellhousing, approximately at the 9 o'clock position
6. Clean the area around the slave cylinder and hydraulic line connections with wire brush and penetrating oil if corroded

Procedure

1. 1

   Access the slave cylinder
   From underneath the vehicle on the driver side, locate the clutch slave cylinder mounted to the left side of the bellhousing. The pushrod extends through the bellhousing to actuate the clutch fork. Note the orientation of the bleeder screw (typically facing upward or outward for bleeding access).
2. 2

   Disconnect the hydraulic line
   Place a drain pan beneath the slave cylinder. Using a line wrench (flare nut wrench), carefully loosen and disconnect the hydraulic line fitting at the slave cylinder inlet. The fitting is typically 3/8" or 7/16". Allow brake fluid to drain into the pan. Cap or plug the hydraulic line immediately to prevent further fluid loss and contamination.
3. 3

   Remove slave cylinder mounting fasteners
   Remove the 2 mounting bolts securing the slave cylinder to the bellhousing using a 9/16" socket or wrench. These bolts thread directly into the bellhousing. Support the cylinder as you remove the second bolt to prevent it from falling.
4. 4

   Remove the old slave cylinder
   Pull the slave cylinder away from the bellhousing. The pushrod will disengage from the clutch fork inside the bellhousing. Remove the cylinder from the vehicle. Inspect the pushrod for wear, bending, or damage. Check the mounting surface on the bellhousing for corrosion or damage.
5. 5

   Inspect clutch fork engagement
   With the slave cylinder removed, shine a light into the bellhousing opening and visually inspect the clutch fork and pivot ball for excessive wear. The fork should move freely on the pivot. If the fork is damaged or excessively worn, the transmission will need to be removed for fork replacement (beyond scope of this procedure).
6. 6

   Prepare new slave cylinder
   Remove the new slave cylinder from packaging. Verify the pushrod length matches the old unit. If the cylinder has a dust boot, ensure it is properly seated. Do not press the pushrod in fully; leave it extended approximately halfway to ease installation and clutch fork engagement.
7. 7

   Install new slave cylinder
   Position the new slave cylinder to the bellhousing, aligning the pushrod with the clutch fork pocket inside the bellhousing. Install the gasket or seal if equipped. Start both mounting bolts by hand, ensuring the bleeder screw is oriented upward or outward for bleeding access. Tighten the mounting bolts evenly in a cross pattern to secure the cylinder firmly to the bellhousing.
8. 8

   Connect hydraulic line
   Remove the plug or cap from the hydraulic line. Thread the line fitting into the slave cylinder inlet port by hand to avoid cross-threading. Use the line wrench to snugly tighten the fitting. Do not overtighten as this can strip the threads or damage the flare seat.
9. 9

   Fill master cylinder reservoir
   Access the brake master cylinder reservoir under the hood (typically on the firewall driver side). Remove the reservoir cap and fill to the MAX line with fresh DOT 3 brake fluid. Keep the reservoir filled throughout the bleeding process to prevent air from entering the system. Verified detail (The 1966 Corvette clutch hydraulic system uses a separate dedicated CLUTCH master cylinder, not the brake master cylinder. Filling the brake reservoir will not feed the clutch system. Also the fluid should be DOT 3 for this era.): Access the clutch master cylinder reservoir, which is separate from the brake master cylinder and mounted on the firewall. Remove the reservoir cap and fill to the MAX line with fresh DOT 3 brake fluid. Keep the reservoir filled throughout the bleeding process to prevent air from entering the system.
10. 10

    Bleed the clutch hydraulic system
    Attach a clear tube to the bleeder screw on the slave cylinder and submerge the other end in a container with a small amount of brake fluid. Have an assistant slowly depress and hold the clutch pedal. Open the bleeder screw 1/4 turn to release fluid and air. Close the bleeder screw before the assistant releases the pedal. Repeat this process until fluid flows with no air bubbles. Typical bleeding requires 10-15 cycles. Check and refill the master cylinder reservoir frequently.
11. 11

    Final tighten bleeder and check for leaks
    With the clutch pedal released, tighten the bleeder screw securely. Remove the bleeding tube. Wipe the slave cylinder clean with a shop rag. Have an assistant pump the clutch pedal several times while you inspect all connections for fluid leaks. Check the hydraulic line fitting and the bleeder screw for any seepage.
12. 12

    Test clutch operation
    With the engine off and transmission in neutral, press the clutch pedal. It should feel firm with consistent resistance and return smoothly. The pedal should not sink to the floor or feel spongy. If spongy, repeat the bleeding process. Check the master cylinder reservoir and top off to the MAX line with DOT 3 brake fluid.

Reassembly

1. Ensure all hydraulic connections are tight and leak-free
2. Verify master cylinder reservoir is filled to MAX line with DOT 4 brake fluid
3. Lower vehicle from jack stands
4. Remove wheel chocks

Verification

• Start the engine and verify clutch pedal operation feels normal with firm, consistent resistance
• With engine running, depress clutch and shift through all gears to confirm proper disengagement
• Test drive the vehicle in a safe area, verifying smooth clutch engagement and disengagement through multiple shifts
• After test drive, re-inspect slave cylinder and all hydraulic connections for leaks
• Recheck brake master cylinder reservoir level and top off if necessary

More procedures for this vehicle