TJ Wrangler Rear Disc Brake Conversion DIY Guide.

Upgrading the rear brakes on a Jeep Wrangler TJ from drums to discs is one of the most worthwhile braking improvements you can make. It improves stopping power consistency, reduces fade on long descents or towing, and makes maintenance easier over time. Below is a practical, workshop-style guide to doing a rear disc brake conversion on a TJ Wrangler.

Rear Disc Brake Conversion on a TJ Wrangler (Step-by-Step Guide)

Why Convert from Drums to Discs?

The factory TJ rear drum brakes work, but they come with limitations:

• They trap heat, which leads to fade under load

• They require frequent adjustment

• They are harder to service on the trail or in the driveway

• They don’t shed water or mud well off-road

Disc brakes solve most of these issues with better heat dissipation, more consistent braking, and simpler pad replacement.

What You’ll Need

There are two common approaches:

1. Bolt-on conversion kit (recommended)

These kits typically include:

• Caliper brackets

• Rotors

• Calipers (often GM-style or similar)

• Brake pads

• Brake hoses

• Hardware

Popular kits are designed around Ford Explorer or GM-style rear disc setups adapted to the TJ axle.

2. Wrecking yard swap (budget option)

Common donor vehicles: Some TJ Models released in Australia came with disc brake rear end from factory. This is the easiest method to do the conversion if you can source a complete axle/ differential. This comes with a degree of risk as the age of these cars now mean the diff internals stand a high probability of being poorly serviced and in need of repair.

Failing that according to the fan pages the Ford explorer does offer a suitable bolt on calliper that will suit if you wish to retain your original diff.

• Ford Explorer (rear discs, especially 95–01 models)

Tools Required

• Jack and axle stands

• Impact gun

• Socket set (metric and SAE)

• Hammer and penetrating oil

• Brake fluid + bleeder kit

• Torque wrench

• Angle grinder (sometimes needed for backing plate removal)

Step 1: Safely Lift and Prepare the Jeep

• Park on level ground

• Chock front wheels

• Lift rear axle and support securely on stands

• Remove rear wheels

Always ensure the axle is stable before working underneath.

Step 2: Remove Drum Brake Assembly

• Remove brake drums (may require tapping with a hammer if seized)

• Disconnect parking brake cable from backing plate

• Remove brake shoes, springs, and hardware

• Disconnect brake line at wheel cylinder

At this point, the drum backing plate is usually bolted to the axle flange. Remove those bolts.

Step 3: Remove Backing Plates

• Spray penetrating oil on flange bolts

• Remove the four axle flange bolts per side

• Slide backing plate off axle shaft

Tip: If the axle seal looks worn or leaking, this is a good time to replace it.

Step 4: Install Caliper Brackets

Depending on your kit:

• Bolt caliper mounting brackets directly to axle flange

• Ensure correct orientation (bleed nipple above the brake flexi line)

• Torque bolts to kit specification

This step is critical—incorrect orientation will cause caliper alignment issues.

Step 5: Install Rotors and Calipers

• Slide rotor onto wheel studs

• Secure temporarily with a wheel nut to hold position

• Install calipers over rotors onto brackets

• Insert brake pads into calipers

• Torque caliper mounting bolts

Check rotor spin for clearance and drag.

Step 6: Parking Brake Setup

This is where TJ conversions vary significantly.

Most kits use:

• Internal drum-in-hat parking brake (Explorer style), or

• Modified cable-to-caliper mechanism

Steps:

• Connect parking brake cables to new system

• Adjust cable tension so parking brake holds firmly at 5–7 clicks

• Verify equal tension left and right

Step 7: Brake Line Plumbing

• Replace rubber lines with kit-supplied hoses or you will need to get flexi hoses fabricated and modify the brake plumbing line.

• Connect hard line to flex line using brake fitting adapters if required

• Ensure no kinks or rubbing on suspension travel

Torque all fittings securely but avoid over-tightening flare nuts.

Step 8: Bleed the Brake System

Bleed in this order:

1. Passenger rear

2. Driver rear

3. Passenger front

4. Driver front

Use fresh DOT 3 or DOT 4 fluid (check kit recommendation).

Continue until all air is removed and pedal feels firm.

Step 9: Final Checks

Before test driving:

• Spin both rear wheels (light drag is normal)

• Check for leaks at all fittings

• Verify parking brake holds vehicle on incline

• Re-torque wheel nuts

Step 10: Bedding in the Brakes

After installation:

• Perform several moderate stops from 30–40 mph

• Avoid hard stops initially

• Allow brakes to cool between cycles

This helps pads and rotors mate properly for maximum performance.

Common Mistakes to Avoid

• Mixing incompatible caliper brackets and rotors

• Forgetting parking brake compatibility

• Improper brake line routing near suspension travel

• Not bleeding ABS-equipped systems correctly (if applicable)

• Reusing old flex lines (not recommended)

A rear disc conversion on a Jeep Wrangler TJ is one of those upgrades that immediately improves drivability, especially if you run larger tires, tow, or do serious off-road work. While it’s not a complicated swap mechanically, the key is choosing a well-matched kit and taking time with brake line and parking brake setup.

Done properly, it feels like a factory upgrade—just with significantly better performance.

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