Brake Lines - Complete Set

Complete replacement of all brake lines from master cylinder to all four wheels, including front and rear brake hoses, hard lines, and junction fittings on a 1970 AMC Rebel Machine.

Warnings

Tools required

Parts

• Complete brake line kit for 1970 AMC Rebel × 1 — Use OEM specification or pre-fabricated kit
• 3/16" steel brake line tubing (25 feet) × 1 — SAE J1047 compliant double-wall steel
• 1/4" steel brake line tubing (10 feet) × 1 — SAE J1047 compliant double-wall steel
• Front brake hoses (left and right) × 2 — Use OEM specification
• Rear brake hoses (left and right) × 2 — Use OEM specification
• Brake line mounting clips × 20 — Assorted sizes
• Brake line union fittings × 6 — 3/16" and 1/4" as needed
• Copper crush washers for hose banjo fittings if applicable × 8 — Use OEM specification
• Brass brake line nuts × 10 — 3/16" and 1/4" inverted flare

Fluids

• DOT 3 or DOT 4 brake fluid — 2 qt

Preparation

1. Park vehicle on level surface and place wheel chocks behind rear wheels before lifting.
2. Photograph all existing brake lines from multiple angles, documenting routing, clip locations, and connections at master cylinder, proportioning valve, axle junctions, and wheel cylinders/calipers.
3. Raise vehicle and support securely on jack stands at all four corners. Ensure vehicle is stable before working underneath.
4. Remove all four wheels to access brake components.
5. Place catch pans under master cylinder and all brake line connection points.
6. If fabricating custom lines, measure and create templates using old brake lines or fabricate lines on the bench using measurements before removing old lines.
7. Clean all brake line connection points with wire brush and penetrating oil, allowing 15-30 minutes soak time on corroded fittings.

Procedure

1. 1

   Drain and disconnect lines at master cylinder
   Using flare nut wrench, carefully loosen all brake line connections at the master cylinder. The 1970 Rebel uses a dual-chamber master cylinder with separate front and rear circuits. Remove lines from front and rear ports. Allow fluid to drain into catch pan. Cap or plug master cylinder ports immediately to prevent contamination and further fluid loss.
2. 2

   Remove lines from proportioning valve and junction blocks
   Locate the proportioning valve (typically mounted on frame rail near master cylinder) and rear axle junction block. Use flare nut wrenches to disconnect lines at these points. The Rebel Machine uses a brake distribution setup with a junction block for the rear axle. Label or photograph each connection point to ensure correct reassembly routing.
3. 3

   Disconnect flexible hoses at front calipers
   At each front wheel, locate the flexible brake hose connection to the caliper. Use two wrenches: one to hold the hose fitting and one to loosen the connection at the caliper to prevent twisting the hose. Remove the banjo bolt or threaded fitting (depending on configuration) and discard any copper crush washers. Immediately plug the caliper port.
4. 4

   Remove front hard lines and frame mounting clips
   Trace the hard brake lines from the master cylinder/proportioning valve area along the frame rails to the front wheel connection points. Remove all mounting clips securing lines to the frame. The Rebel uses stamped spring clips; carefully pry these open to release lines. Disconnect hard lines from flexible hoses at the frame-mounted junction points using flare nut wrenches. Remove entire front line assembly.
5. 5

   Disconnect rear flexible hoses and hard lines
   At the rear axle, disconnect the flexible hoses where they connect to the hard lines on the axle housing. Use flare nut wrenches on the hard line fittings while holding the hose fitting. Remove the hose retaining clips/brackets from the axle housing. Follow the rear hard lines forward to the junction block/proportioning valve and remove all mounting clips along the frame and body.
6. 6

   Remove rear axle lines and wheel cylinder connections
   Disconnect brake lines at both rear wheel cylinders using flare nut wrenches. Remove the hard lines that run along the rear axle housing, noting the routing and any clips or brackets. The Rebel's rear axle typically has lines running along the top or side of the axle tube. Remove complete rear line assembly.
7. 7

   Fabricate or prepare new brake lines
   Using the old lines as templates, fabricate new lines with proper double inverted flares on each end. Cut tubing to length with tubing cutter (not hacksaw if possible to ensure square cut). Deburr all cut ends thoroughly inside and out. Form bends using tubing bender, maintaining minimum 3-inch radius to prevent kinking. Create double flares using flaring tool, ensuring flare seats are clean and properly formed with no cracks. If using pre-fabricated kit, verify all lines match original routing and length.
8. 8

   Install master cylinder to proportioning valve lines
   Begin installation at master cylinder. Thread new lines into master cylinder ports by hand to ensure proper thread engagement. Route lines to proportioning valve following original path. Install mounting clips at frame rail locations. Tighten fittings at master cylinder and proportioning valve using flare nut wrenches, ensuring lines are not twisted or under tension. Fittings should be snug but not over-torqued (typically 10-15 ft-lbs for 3/16" line, 12-17 ft-lbs for 1/4" line, but verify with a torque-indicating flare nut wrench if available).
9. 9

   Install front brake lines to frame
   Route new hard lines from proportioning valve area along frame rails to front wheel junction points. Install all mounting clips, ensuring lines have proper clearance from exhaust manifolds, steering components, and suspension travel. Lines must not contact any moving parts or hot surfaces. Install frame-mounted junction fittings where hard lines will connect to flexible hoses.
10. 10

    Install front flexible brake hoses
    Install new front flexible hoses, connecting first to the frame-mounted hard line junctions. Ensure hoses are not twisted by checking orientation of fittings at both ends. Route hose to caliper, ensuring adequate length for full suspension travel and steering lock-to-lock movement. Install new copper crush washers (if banjo-type fitting) and connect to caliper. Tighten to secure but avoid over-tightening which can damage hose fittings. Typical torque for banjo bolts is 18-22 ft-lbs, threaded hose fittings 12-15 ft-lbs.
11. 11

    Install rear brake lines from proportioning valve to axle
    Route new hard lines from proportioning valve/junction block area along frame to rear axle connection points. Follow original routing, installing all mounting clips at frame and body locations. Ensure clearance from driveshaft, exhaust system, and fuel tank. Connect lines at forward junction points and at rear axle flexible hose mounting locations.
12. 12

    Install rear flexible hoses and axle hard lines
    Install new rear flexible hoses at the frame-to-axle connection points, ensuring proper length for full axle travel. Install hose retaining brackets to axle housing. Route and install hard lines along rear axle to each wheel cylinder, securing with appropriate clips. Connect lines to wheel cylinders, ensuring proper thread engagement and using flare nut wrenches to avoid rounding off fittings.
13. 13

    Verify routing and clearances
    Thoroughly inspect entire brake line installation. Check every line for proper clearance from: exhaust system (minimum 2 inches), driveshaft, suspension components at full droop and compression, steering components at full lock, and body/frame edges. Verify all mounting clips are installed and lines are secure. Check that no lines are kinked, twisted, or under tension. Have an assistant cycle steering lock-to-lock and compress/extend suspension while you verify no interference occurs.
14. 14

    Fill and bleed brake system
    Fill master cylinder with fresh DOT 3 or DOT 4 brake fluid to proper level. Bleed brake system in proper sequence: right rear, left rear, right front, left front. Use either two-person manual bleeding method or vacuum bleeder. At each wheel, attach clear hose to bleeder screw, submerge end in clean brake fluid in container. Open bleeder, pump brake pedal (or apply vacuum) until fluid flows with no air bubbles. Close bleeder before releasing pedal/vacuum. Maintain master cylinder fluid level throughout bleeding process. Continue until firm pedal is achieved with no sponginess.
15. 15

    Pressure test and leak inspection
    With vehicle still on jack stands, have assistant apply firm, steady pressure to brake pedal (approximately 50 lbs force) and hold for 2 minutes. Inspect every connection point, fitting, and line section for any signs of fluid seepage or leakage. Check all flare connections, hose fittings at calipers and wheel cylinders, and master cylinder connections. Pedal should remain firm with no sinking. If any leaks are found, drain that section, correct the problem, and re-bleed. Repeat pressure test until no leaks are present.

Reassembly

1. Reinstall all four wheels and torque lug nuts to specification (typically 75-85 ft-lbs for 1970 AMC Rebel).
2. Lower vehicle to ground.
3. Top off master cylinder to proper level with fresh brake fluid.
4. Pump brake pedal multiple times to ensure firm pedal before attempting to move vehicle.
5. Clean any brake fluid spills from painted surfaces, frame, and components with water.

Verification

• Perform static brake pedal test: With engine off, pump pedal 3-4 times and hold firm pressure. Pedal should be solid with no gradual sinking over 1 minute period. Any pedal sink indicates air in system or leak.
• Start engine (power brakes) and verify pedal drops slightly then remains firm. Apply firm pressure and hold for 1 minute - no sinking should occur.
• Perform low-speed test in safe area: At 5-10 mph, apply brakes firmly. Vehicle should stop smoothly with no pulling to either side and pedal should feel firm and responsive.
• Perform moderate-speed test in safe area: At 20-25 mph, apply brakes progressively from light to firm. Vehicle should stop straight with no vibration, noise, or pedal pulsation.
• After initial test drive (20-30 miles), re-inspect all connections for leaks and re-check master cylinder fluid level.
• Re-bleed brakes if pedal feel is not completely firm or if any sponginess is detected.
• CRITICAL: If brake pedal feels soft, spongy, sinks under pressure, or if vehicle pulls to one side during braking, DO NOT drive the vehicle. Re-inspect all work and re-bleed the system. Seek professional assistance if issues cannot be resolved.

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