Replace a single damaged or corroded brake line on a 1966 Chevrolet Corvette 327ci V8, including bleeding the brake system to restore safe braking function.

Warnings

Tools required

Parts

• 3/16" steel brake line (measure and cut to length) × 1 — Use OEM specification nickel-copper or steel brake line
• Brake line fittings (if not using pre-flared line) × 2 — 3/16" inverted flare fittings
• Brake line clips and brackets × 2 — Use OEM specification

Fluids

• DOT 4 Brake Fluid — 1 qt

Preparation

1. Park vehicle on level surface and chock wheels that will remain on ground
2. Loosen lug nuts on wheel(s) nearest damaged brake line before raising vehicle
3. Raise vehicle with floor jack and support securely on jack stands at appropriate frame lift points
4. Remove wheel(s) as needed to access damaged brake line
5. Identify the damaged section of brake line and trace its routing from connection point to connection point
6. Clean area around brake line fittings with wire brush and apply penetrating oil to fittings, allow 10-15 minutes to penetrate
7. Place absorbent rags or drip pans under work area to catch brake fluid spills
8. Have all replacement materials, tools, and fresh DOT 4 brake fluid ready before disconnecting any lines

Procedure

1. 1

   Measure and prepare replacement brake line
   Using the damaged line as a template, measure the exact length needed from connection point to connection point. Add 6 inches to this measurement for bending allowance. Cut new 3/16" brake line to this length using tubing cutter for clean, square cuts. If the damaged line cannot be used as a template, route string or flexible wire along the intended path and measure that length, then add bending allowance.
2. 2

   Create double flares on line ends
   Slide the appropriate flare nuts onto each end of the new brake line with threads facing outward. Secure the line in the flaring tool according to manufacturer instructions, with approximately 1/4" of tubing protruding above the die. Create a double inverted flare (also called SAE flare) on each end. This is critical - single flares are not acceptable for brake systems and will leak under pressure. Inspect each flare for cracks, splits, or irregularities before proceeding.
3. 3

   Form bends in replacement line
   Using a tube bending tool or spring-type bender, carefully form the necessary bends to match the routing of the original line. Make gradual, smooth bends with a minimum radius of 3 times the tube diameter to avoid kinking or collapsing the line. Test-fit the new line in position before disconnecting the old line to verify proper routing and length. Adjust bends as necessary.
4. 4

   Disconnect damaged brake line at master cylinder or junction block end
   Using the appropriate flare nut wrench (typically 3/8" or 1/2"), carefully loosen the flare nut at the upper connection point (closest to master cylinder or junction block). Hold the fitting body stationary with a backup wrench while turning the flare nut to prevent twisting the line or damaging the fitting. Brake fluid will drain from the open connection - be prepared with rags or a catch container. Cap or plug the master cylinder port immediately to minimize fluid loss and prevent air entry.
5. 5

   Disconnect damaged brake line at wheel cylinder or caliper end
   Using flare nut wrench, disconnect the lower end of the damaged brake line at the wheel cylinder (drum brake) or caliper (if disc brake equipped). Again use a backup wrench to prevent twisting. Allow remaining fluid to drain into catch container. Cap or plug the wheel cylinder or caliper port to prevent further fluid loss and contamination.
6. 6

   Remove mounting clips and extract damaged line
   Release the damaged brake line from any mounting clips or brackets along its routing path. There are typically 2 to 3 mounting points depending on line location. Note the exact position of each clip for reinstallation of the new line. Remove the old line completely from the vehicle.
7. 7

   Install new brake line at master cylinder or junction block end
   Remove cap or plug from master cylinder or junction block port. Thread the flare nut of the new brake line onto the fitting by hand, ensuring it threads smoothly without cross-threading. Once hand-tight, use flare nut wrench to tighten securely. Do not overtighten - snug the fitting firmly but avoid excessive force that could damage the flare or strip threads. A properly seated double flare requires only moderate torque to seal.
8. 8

   Route and secure new brake line
   Route the new brake line along the same path as the original, ensuring it does not contact the exhaust system, suspension components, or any sharp edges. Install mounting clips and brackets at the original locations, ensuring the line is held securely but not kinked or pinched. The line should follow smooth curves without any sharp bends or tension.
9. 9

   Connect new brake line at wheel cylinder or caliper end
   Remove cap or plug from wheel cylinder or caliper port. Thread the flare nut onto the fitting by hand until fully seated, then tighten with flare nut wrench. Again, use moderate torque - sufficient to seal without damaging the flare. Verify that the line is not twisted or under tension at either connection point.
10. 10

    Fill master cylinder reservoir
    Remove the master cylinder reservoir cap and fill to the FULL line with fresh DOT 3 brake fluid. The 1966 Corvette uses a single-bore master cylinder with one reservoir serving both front and rear circuits. Keep the reservoir at least half full throughout the bleeding process to prevent air from being drawn into the system.
11. 11

    Bleed brake system at affected wheel
    Attach clear plastic tubing to the bleeder screw on the wheel cylinder or caliper served by the replaced line. Submerge the other end of the tubing in a container partially filled with fresh brake fluid. Have an assistant pump the brake pedal 3 to 4 times and hold firm pressure. Open the bleeder screw approximately 1/2 turn while assistant maintains pedal pressure. Fluid and air bubbles will flow into the container. Close the bleeder screw before the pedal reaches the floor. Repeat this process until fluid flows without air bubbles. Check and refill master cylinder reservoir frequently during bleeding.
12. 12

    Bleed remaining wheels in proper sequence
    On the 1966 Corvette, bleed brakes in the following sequence: right rear, left rear, right front, left front (furthest from master cylinder to closest). This ensures all air is purged from the system. Repeat the bleeding process at each wheel until clean, bubble-free fluid flows from each bleeder. The brake pedal should become progressively firmer as air is removed from the system.
13. 13

    Inspect all connections for leaks
    With brake pedal released, visually inspect all brake line connections, including both ends of the newly installed line. Apply firm brake pedal pressure and hold for 30 seconds while inspecting for any fluid seepage at connections. If any leaks are detected, relieve pedal pressure, tighten the affected fitting slightly, and retest. Do not proceed if any leaks persist.

Reassembly

1. Reinstall wheel(s) and hand-tighten lug nuts in star pattern
2. Lower vehicle to ground and torque lug nuts to 80 ft-lbs in star pattern
3. Check master cylinder fluid level one final time and top off to FULL line with DOT 4 brake fluid
4. Securely install master cylinder reservoir cap
5. Dispose of old brake fluid and contaminated rags according to local environmental regulations
6. Clean any brake fluid spills from chassis or suspension components with water

Verification

• With engine off, pump brake pedal several times - pedal should become firm and hold steady pressure without slowly sinking
• Start engine (if power brakes equipped on some 1966 models) and verify pedal height remains consistent
• Perform a low-speed brake test in a safe area - vehicle should stop in a straight line without pulling to either side
• Check for any brake fluid leaks at all connections after initial test - inspect again after 50 miles of driving
• Verify brake pedal effort is normal for a non-power assisted system (requires significant foot pressure)
• Perform a final visual inspection of the new brake line routing to ensure it does not contact any moving parts, exhaust, or sharp edges

More procedures for this vehicle