This procedure addresses a common misunderstanding: the 1966 Chevrolet Corvette was not equipped with ABS (Anti-lock Braking System). This generation used a conventional hydraulic brake system with a single master cylinder.

Warnings

Tools required

Parts

• Master cylinder (single reservoir or dual reservoir depending on configuration) × 1 — Use OEM specification or equivalent
• Master cylinder mounting gasket/seal × 1 — Use OEM specification
• Brake line crush washers (if applicable) × 4 — Use OEM specification

Fluids

• DOT 4 Brake Fluid — 1 qt

Preparation

1. Verify the actual concern: if diagnosing a braking issue, inspect master cylinder, brake lines, wheel cylinders, and brake adjustment rather than searching for non-existent ABS components
2. Park vehicle on level surface and place wheel chocks behind rear wheels
3. Pump brake pedal several times to relieve any residual vacuum in the brake booster
4. Open master cylinder reservoir and use turkey baster to remove as much old brake fluid as possible
5. Raise front of vehicle and support securely on jack stands if master cylinder access requires it (most can be accessed from engine bay)

Procedure

1. 1

   Disconnect battery negative terminal
   Disconnect the negative battery cable to prevent accidental electrical shorts while working near the firewall and master cylinder mounting area.
2. 2

   Remove master cylinder reservoir cap
   Remove the master cylinder reservoir cap and set aside. This prevents vacuum lock during brake line removal and allows you to monitor fluid level.
3. 3

   Disconnect brake lines from master cylinder
   Using a flare nut wrench, carefully loosen and disconnect the brake line(s) from the master cylinder outlet port(s). The 1966 Corvette master cylinder typically has one or two outlet ports (depending on single vs. dual-circuit configuration); the front/rear circuits are split downstream at a distribution block, not by individual lines at the master cylinder. Confirm the exact number of outlet connections on your specific vehicle. Immediately cap or plug the open line ends to minimize fluid loss and contamination. Allow fluid to drain into a suitable container.
   ⚠Use a flare nut wrench rather than an open-end wrench to prevent rounding off the soft brass brake line fittings. These fittings are often corroded and fragile on vehicles of this age.
4. 4

   Disconnect pushrod from brake pedal (if required)
   From inside the vehicle, locate the master cylinder pushrod connection at the brake pedal. Remove the retaining clip or cotter pin and slide the pushrod off the brake pedal pivot pin. Note the orientation and any spacers or bushings for reassembly. On some 1966 Corvettes, the master cylinder can be removed without disconnecting the pushrod if you are only replacing the cylinder body.
5. 5

   Remove master cylinder mounting nuts
   From the engine bay, locate the 2 master cylinder mounting nuts securing the unit to the firewall or brake booster (if power brake equipped). Remove these nuts completely. If corroded, apply penetrating oil and allow time to soak before attempting removal.
6. 6

   Remove master cylinder from vehicle
   Carefully pull the master cylinder forward and away from the firewall/booster, guiding the pushrod out of the rear of the cylinder body. Be prepared for residual brake fluid to drain from the cylinder. Place the old master cylinder in a drain pan.
7. 7

   Inspect mounting surface and pushrod
   Clean the firewall/booster mounting surface with a wire brush. Inspect the pushrod for wear, bending, or damage. Measure pushrod length if replacing master cylinder, as incorrect pushrod length will cause improper brake function or pedal feel. The pushrod should have minimal side-to-side play in the booster (if equipped).
8. 8

   Prepare new master cylinder
   Bench bleed the new master cylinder before installation to prevent air from entering the brake system. Mount the cylinder in a vise (protected with soft jaws), install bleeding tubes from outlet ports back into the reservoir, fill reservoir with fresh DOT 3 brake fluid, and slowly stroke the pushrod until no air bubbles emerge from the tubes. Remove bleeding tubes and cap ports temporarily.
9. 9

   Install new master cylinder
   Position the new master cylinder gasket/seal on the mounting surface. Guide the pushrod into the rear of the master cylinder and align the mounting studs with the firewall/booster holes. Install the 2 mounting nuts and tighten securely. Torque specification not available; tighten to snug plus approximately 1/4 turn, being careful not to overtighten and crack the cast iron cylinder body or distort the mounting flange.
10. 10

    Reconnect pushrod to brake pedal
    From inside the vehicle, reconnect the master cylinder pushrod to the brake pedal pivot pin. Install any spacers or bushings in their original orientation, then secure with the retaining clip or new cotter pin. Verify the pushrod moves freely through its full stroke without binding.
11. 11

    Reconnect brake lines to master cylinder
    Remove the temporary caps from the brake lines and master cylinder ports. Thread each brake line into its corresponding master cylinder port by hand first to ensure proper threading, then tighten with a flare nut wrench. Typical tightness is snug plus 1/4 to 1/2 turn; do not overtighten or you will strip the threads or crack the brass fitting.
12. 12

    Fill master cylinder reservoir
    Fill the master cylinder reservoir to the proper level with fresh DOT 3 brake fluid. Do not overfill. Keep the reservoir topped off throughout the bleeding process.
13. 13

    Bleed brake system
    Bleed the brake system starting with the wheel farthest from the master cylinder (typically right rear), then left rear, right front, and left front. At each wheel, attach a clear tube to the bleeder screw, submerge the other end in a container of clean brake fluid, have an assistant pump the brake pedal 3-4 times and hold, open the bleeder screw until fluid stops flowing, close the bleeder, then release the pedal. Repeat until no air bubbles emerge. Maintain reservoir level throughout bleeding process.
14. 14

    Check for leaks and proper operation
    With the system bled, inspect all brake line connections at the master cylinder for leaks. Start the engine (if power brake equipped) and pump the brake pedal several times. The pedal should feel firm with no excessive travel or sponginess. If pedal is soft, repeat bleeding procedure.
15. 15

    Reconnect battery and perform final checks
    Reconnect the battery negative terminal. Check brake fluid level one final time and install reservoir cap. Test brake pedal feel with engine running and verify proper brake operation before road testing. Perform a low-speed test in a safe area to confirm brakes engage properly before returning to normal driving.

Reassembly

1. Ensure all brake line fittings are tightened securely but not overtightened
2. Verify master cylinder reservoir is filled to proper level and cap is installed
3. Confirm brake pedal has firm feel with no excessive travel before road testing
4. Dispose of old brake fluid according to local environmental regulations

Verification

• Check for brake fluid leaks at all master cylinder connections with vehicle running and brake pedal applied
• Verify brake pedal height and feel are normal with firm resistance and no sponginess
• Perform a low-speed brake test in a safe area to confirm even braking with no pull to either side
• Verify brake warning light (if equipped) is not illuminated
• Check brake fluid level after test drive and top off if necessary

More procedures for this vehicle