Complete replacement of all brake lines from master cylinder to all four wheel calipers, including routing, securing, and bleeding the entire brake system.

Warnings

Tools required

Parts

• Complete brake line set (front to rear main lines) × 1 — OEM or pre-bent aftermarket kit for JK Wrangler
• Brake line clips and mounting brackets × 1 — Usually included with line kit
• Copper crush washers for caliper banjo bolts (if applicable) × 8 — Check caliper type - some use flare fittings
• Brake fluid (DOT 4) × 4 — Mopar DOT 4

Fluids

• brake — 3 qt

Preparation

1. Park vehicle on level concrete surface and place wheel chocks behind rear wheels
2. Apply penetrating oil to all brake line fittings at master cylinder, ABS module, frame junctions, and all four calipers - allow to soak minimum 2 hours, preferably overnight
3. Loosen wheel lug nuts on all four wheels while vehicle is on ground (do not remove)
4. Raise vehicle with floor jack and support on four jack stands at frame rails - vehicle must be level and secure
5. Remove all four wheels and set aside
6. Place catch pans under master cylinder and work areas to contain brake fluid spills
7. Open master cylinder reservoir cap to prevent vacuum lock during line removal
8. Photograph or diagram existing brake line routing before removal - pay special attention to clip locations and frame passage points

Procedure

1. 1

   Remove brake lines from front calipers
   Starting at the front wheels, use line wrench to disconnect brake line fittings from both front calipers. Immediately cap or plug open fittings to prevent fluid loss and contamination. If calipers have banjo bolts instead of threaded fittings, remove the banjo bolt and discard the copper crush washers. Allow brake fluid to drain into catch pan.
   ⚠Use only line wrenches, not standard open-end wrenches, to prevent rounding off soft brass fittings. If fitting begins to round, stop and use penetrating oil or heat carefully with propane torch (keep away from rubber components).
2. 2

   Remove brake lines from rear calipers
   Move to rear wheels and disconnect brake line fittings from both rear calipers using line wrench. Cap or plug open fittings. Note any differences in fitting types between front and rear if present on your specific model year.
3. 3

   Disconnect lines from ABS module and junction blocks
   Locate ABS module (mounted on frame rail near master cylinder). Using line wrench, carefully disconnect brake lines from ABS module outlets. On JK Wrangler, there are typically four outlet ports. Label or photograph which line connects to which port. Disconnect any frame-mounted junction blocks or distribution tees, noting their exact orientation and mounting positions.
   ⚠ABS module ports are aluminum and easily damaged. Do not apply excessive force. If fitting will not break free, apply more penetrating oil and wait.
4. 4

   Remove lines from master cylinder
   At the master cylinder (firewall-mounted), use line wrench to disconnect the main brake lines. There are typically two lines exiting the master cylinder on these vehicles. Support lines as you disconnect to prevent stress on fittings. Allow remaining fluid to drain from master cylinder reservoir.
5. 5

   Remove all brake line mounting clips and brackets
   Working from front to rear, remove all clips, brackets, and retainers securing brake lines to frame rails, suspension components, and body. Document each clip location as you remove them - proper routing and support is critical for preventing vibration damage. Keep all clips and hardware organized for reuse.
6. 6

   Remove old brake lines completely
   Carefully extract old brake lines from vehicle, noting how they route through frame passages, over axles, and around suspension components. Pay particular attention to areas where lines pass through body/frame holes or near heat sources (exhaust). Compare old lines to new line kit to verify correct application before proceeding.
7. 7

   Prepare master cylinder and ABS module connections
   Clean all threaded ports on master cylinder and ABS module with wire brush. Inspect threads for damage - any stripped threads will require component replacement before proceeding. Apply small amount of brake fluid to threads to assist with initial threading of new lines.
   ⚠️Do NOT use thread sealant, Teflon tape, or any other compounds on brake line threads. These can contaminate the brake system and cause brake failure.
8. 8

   Install main lines to master cylinder
   Begin installation by threading new brake lines into master cylinder by hand - ensure at least 3-4 full turns can be made by hand before using wrench. If fitting binds immediately, remove and inspect for cross-threading. Once hand-tight, use line wrench and torque wrench to tighten fittings to specification. Do not overtighten.
   ⚠️Cross-threaded fittings will leak and cause brake failure. Always start threads by hand and verify smooth threading before applying tools.
   Torque spec

   Line Fittings23 Nm (17 lb-ft)
9. 9

   Route and install lines to ABS module and junctions
   Following your documentation from removal, route new lines along frame rails to ABS module. Ensure lines do not contact exhaust, suspension components, or sharp edges. Install lines to ABS module ports in correct positions, hand-threading first, then torquing to specification. Install any junction blocks or tees in their original positions.
   ⚠Brake lines must have adequate clearance from all moving suspension components through full range of motion. Compress suspension by hand to verify clearance before securing clips.
   Torque spec

   Line Fittings23 Nm (17 lb-ft)
10. 10

    Route lines to all four wheels
    Route new lines from ABS module/junction points to each wheel location. Follow OEM routing exactly, ensuring lines pass through same frame holes and around same obstacles as originals. Bend lines carefully as needed using proper bending tools - avoid kinking. Leave final positioning slightly loose until all connections are made.
11. 11

    Connect lines to all four calipers
    At each wheel, connect brake line to caliper. If using threaded fittings, hand-thread first then torque to specification with line wrench. If using banjo bolts, install NEW copper crush washers on both sides of banjo fitting, then torque banjo bolt to specification. Verify each connection is secure and properly seated.
    ⚠️Never reuse old copper crush washers on banjo fittings - they will leak. Always install new washers on both sides of banjo.
    Torque spec

    Line Fittings23 Nm (17 lb-ft)
12. 12

    Install all mounting clips and brackets
    Working systematically from master cylinder to each wheel, install all brake line clips and brackets in their original positions. Torque bracket bolts to specification. Ensure lines are supported at regular intervals (typically every 12-18 inches) and cannot vibrate against frame or other components. Double-check clearance from suspension, exhaust, and moving parts.
    Torque spec

    Bracket Bolts117 Nm (86 lb-ft)
13. 13

    Fill brake fluid reservoir
    Fill master cylinder reservoir to MAX line with fresh DOT 4 brake fluid from a sealed container. Keep reservoir filled throughout bleeding process - never allow level to drop below MIN or air will enter system.
    ⚠Use only DOT 4 brake fluid. Do not mix DOT 3 and DOT 4. Never use DOT 5 (silicone) fluid in this vehicle - it is incompatible with ABS system.
14. 14

    Bleed brake system completely
    Bleed brakes in this sequence: passenger rear, driver rear, passenger front, driver front. At each wheel: attach clear hose to bleeder screw, submerge other end in container with clean brake fluid. Have assistant pump brake pedal 3-5 times and hold. Open bleeder screw 1/2 turn, allow fluid/air to flow until pedal reaches floor, close bleeder before assistant releases pedal. Repeat until no air bubbles appear in hose. Torque bleeder screws to specification when complete at each wheel. Check and refill reservoir frequently.
    ⚠️Air in brake lines causes spongy pedal and reduced braking. Continue bleeding until pedal is firm and no bubbles appear. May require multiple rounds of bleeding entire system.
    Torque spec

    Bleeder Screw16 Nm (12 lb-ft)
15. 15

    Inspect all connections for leaks
    With system bled and pedal firm, inspect every brake line connection for leaks while assistant applies firm, steady pressure to brake pedal. Check master cylinder, ABS module, junction blocks, and all four calipers. Wipe each fitting dry, apply pedal pressure, then inspect for seepage. Any leak requires immediate correction - retorque fitting or replace if damaged.
    ⚠️Even a small leak will eventually cause brake failure. Do not drive vehicle if ANY leak is present.

Reassembly

1. Reinstall all four wheels and hand-thread lug nuts
2. Lower vehicle to ground and remove jack stands
3. Torque wheel lug nuts to specification in star pattern while vehicle is on ground
4. Top off brake fluid reservoir to MAX line with fresh DOT 4 fluid
5. Clean any brake fluid spills from painted surfaces immediately with water

Verification

• Pump brake pedal 10-15 times - pedal must feel firm and not sink to floor when held under pressure
• Start engine (power brakes) and verify pedal height drops slightly but remains firm
• Perform visual inspection of all brake line connections for leaks with engine running and pedal applied
• Test drive in safe area at low speed (under 15 mph) to verify brakes engage properly and vehicle stops straight
• After test drive, recheck all fittings for leaks and verify brake fluid level has not dropped
• Perform final test drive gradually increasing speed, testing brakes every 10 mph up to 45 mph
• After 50-100 miles of driving, recheck all brake line connections and fluid level - retorque any fittings if needed and rebleed if pedal becomes spongy

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