Upgrading the rear brakes on an XJ Cherokee to discs improves stopping power and reduces maintenance. A Jeep Xj Rear Disk Brake Conversion is one of the most popular modifications for these classic SUVs. It addresses the weak factory drum brakes that often fade under heavy use or off-road conditions.
You might be tired of adjusting drum brakes or dealing with poor pedal feel. This conversion swaps out the troublesome drums for reliable disc brakes. It is a straightforward project that delivers immediate results.
Let’s break down everything you need to know. We will cover parts, tools, installation steps, and common questions. By the end, you will be ready to tackle this upgrade yourself.
Why Convert To Rear Disc Brakes On An XJ Cherokee
Factory drum brakes on the XJ are adequate for light duty. But they have several downsides. Drums are prone to overheating, especially after water crossings or long descents. They also collect mud and debris easily.
Disc brakes offer better heat dissipation. They shed water and mud faster. This means more consistent stopping power in all conditions. You will also notice a firmer brake pedal feel.
Maintenance is simpler too. No more adjusting star wheels or replacing springs. Pad and rotor swaps are quick and clean. Many owners report longer pad life with discs.
Jeep Xj Rear Disk Brake Conversion
This is the core of your upgrade. A Jeep Xj Rear Disk Brake Conversion typically uses parts from other vehicles. The most common donor is the Ford 8.8 axle, which came with factory rear discs. But you can also use aftermarket kits.
There are two main paths: a full axle swap or a bracket kit. The axle swap gives you stronger axles and disc brakes in one move. The bracket kit lets you keep your stock Dana 35 or Chrysler 8.25 axle.
Both options work well. Your choice depends on budget and intended use. Let’s look at the parts you will need for each approach.
Parts Needed For A Bracket Conversion Kit
If you keep your stock axle, you need a conversion kit. These kits include mounting brackets, calipers, rotors, and hardware. Most kits use Grand Cherokee ZJ rear calipers and rotors.
- Conversion bracket kit (includes brackets, bolts, and instructions)
- ZJ rear calipers (new or remanufactured)
- ZJ rear rotors (solid or vented)
- New brake pads for ZJ rear
- Rubber brake hose or banjo bolt adapters
- Parking brake cables (ZJ or aftermarket)
- Brake fluid (DOT 3 or DOT 4)
- Anti-seize compound
You may also need a proportioning valve adjustment. Some kits include a residual pressure valve for the rear circuit. Check the kit instructions carefully.
Parts Needed For A Ford 8.8 Axle Swap
Swapping in a Ford 8.8 axle gives you stronger shafts and disc brakes. The axle came in Ford Explorers and Mustangs from 1995-2001. You want one with 31-spline shafts and disc brakes.
- Ford 8.8 axle assembly (complete with brakes)
- Spring perches and shock mounts (weld-on)
- New U-bolts and plates
- Brake line adapter fittings
- Parking brake cables (custom length)
- New rotors and pads for the Ford axle
- Differential cover and gasket
- Gear oil (75W-140 for limited slip)
This swap requires welding. You must cut off the old perches and weld on new ones to match the XJ spring width. The axle is about 1.5 inches wider, so check wheel offset.
Tools You Will Need For The Job
Having the right tools makes the job smoother. You likely already own most of these. Here is a list of essentials.
- Floor jack and jack stands
- Socket set (metric and standard)
- Wrenches (combination and flare nut)
- Brake line wrench (for hard lines)
- Torque wrench
- Wire brush or grinder
- Brake bleeder kit or helper
- Pry bar and hammer
- Penetrating oil (like PB Blaster)
- Safety glasses and gloves
If you are welding perches, you need a MIG welder and angle grinder. For a bracket kit, no welding is required. Most kits bolt directly to the axle flange.
Step-By-Step Installation Guide For Bracket Kit
This section covers the bracket conversion on a stock Dana 35 or Chrysler 8.25 axle. The process is similar for both. Work safely and take your time.
Step 1: Prepare The Vehicle
Park on level ground. Chock the front wheels. Loosen the rear lug nuts slightly before jacking. Then lift the rear with a floor jack and place jack stands under the axle tubes.
Remove the rear wheels and tires. Set them aside. Now you have clear access to the drum brakes.
Step 2: Remove Drum Brake Components
Remove the brake drum. It may be stuck from rust. Use a pry bar gently behind the drum or tap with a hammer. If the drum is seized, back off the adjuster through the backing plate slot.
Once the drum is off, remove the shoes, springs, and hardware. Use pliers and a screwdriver. Take photos for reference if needed. Remove the backing plate by unbolting it from the axle flange.
Disconnect the hard brake line at the wheel cylinder. Be careful not to damage the line. Cap the line to prevent fluid loss and dirt entry.
Step 3: Install The Conversion Brackets
Clean the axle flange surface with a wire brush. Apply anti-seize to the studs. Position the new bracket over the studs. Most kits use the same four studs that held the backing plate.
Tighten the nuts to spec. Do not overtighten. The bracket must sit flush against the flange. Some kits include a spacer for the parking brake cable bracket.
Step 4: Install Rotors And Calipers
Slide the new rotor over the studs. It should spin freely. If it binds, check the bracket alignment. Install the caliper bracket if separate from the main bracket.
Attach the caliper to the bracket. Use new hardware included in the kit. Make sure the caliper slides smoothly on the pins. Apply a thin layer of caliper grease to the pins.
Install the brake pads into the caliper. Compress the caliper piston if needed. Use a C-clamp or brake piston tool. Slide the caliper over the rotor and secure it.
Step 5: Connect Brake Lines
You need to connect the hard line to the caliper. Most kits use a flexible brake hose. The hose connects to the hard line at the frame bracket. Then it runs to the caliper.
Use new copper washers at the banjo bolt. Tighten the banjo bolt to spec. Do not overtighten. Then connect the other end of the hose to the hard line. Use a flare nut wrench to avoid rounding.
Bleed the brake system. Start at the passenger rear, then driver rear, then front. Use a helper or a one-man bleeder kit. Pump the pedal, open the bleeder, close it, release pedal. Repeat until no air bubbles appear.
Step 6: Adjust Parking Brake
The parking brake is the trickiest part. Most kits use a cable from a ZJ or an aftermarket cable. You may need to modify the factory cable bracket.
Route the cable from the lever to the caliper. Attach it to the caliper arm. Adjust the cable tension at the equalizer under the vehicle. The lever should engage with 4-6 clicks.
Test the parking brake on a slight incline. If it holds, you are good. If not, adjust further or check cable routing for binding.
Step-By-Step Guide For Ford 8.8 Axle Swap
This swap is more involved. It requires welding and careful measurement. But the result is a stronger axle with disc brakes.
Step 1: Remove Old Axle
Support the vehicle on jack stands. Remove the wheels. Disconnect the brake lines, parking brake cables, and shock absorbers. Remove the leaf spring U-bolts.
Support the axle with a jack. Lower it slowly. Pull it out from under the vehicle. Be careful of the brake lines and vent tube.
Step 2: Prepare The Ford 8.8 Axle
Clean the axle thoroughly. Remove the old spring perches and shock mounts with a grinder. Measure the XJ spring center-to-center distance. It is about 41.5 inches on most models.
Weld new perches at the correct width. Use a level to ensure they are square. Weld shock mounts in the stock location. Paint the welds to prevent rust.
Step 3: Install The Axle
Lift the axle into place. Use new U-bolts and plates. Torque the U-bolts to spec. Reinstall the shocks and brake lines. You may need adapter fittings for the brake lines.
Bleed the brakes as described earlier. The Ford calipers use a different bleeder screw. Use a 10mm wrench. Bleed in the same order.
Step 4: Parking Brake Setup
The Ford axle has its own parking brake cables. You need to connect them to the XJ lever. This often requires custom cables or adapters. Several companies sell pre-made cables for this swap.
Adjust the cables at the caliper and the equalizer. Test the parking brake function. It should hold the vehicle on a grade.
Common Issues And How To Fix Them
Even with a good kit, you may encounter problems. Here are some frequent issues and solutions.
- Soft brake pedal: Air in the system. Bleed again thoroughly. Check for leaks at connections.
- Rotor rubbing: Bracket not centered. Loosen bolts and realign. Shim if necessary.
- Parking brake not holding: Cable too loose or caliper mechanism stuck. Adjust or lubricate.
- Brake fluid leak: Banjo bolt not tight or copper washer damaged. Replace washer and retorque.
- Calipers not sliding: Rust on pins. Clean and grease with caliper grease.
Most issues are simple to fix. Take your time and double-check each step. A test drive with gentle braking helps identify problems early.
Benefits Of The Conversion Beyond Stopping Power
Improved stopping is the main reason. But there are other benefits. Disc brakes are easier to inspect. You can see pad thickness without removing the wheel. Drum brakes require full disassembly.
Discs also reduce unsprung weight. The caliper and rotor combo is lighter than a drum assembly. This improves suspension response and ride quality.
Off-road performance improves. Mud and water clear from discs quickly. Drums trap debris and lose effectiveness. Discs self-clean with each rotation.
Resale value may increase. Many XJ buyers look for disc brake conversions. It is a sign of a well-maintained or upgraded vehicle.
Cost Breakdown For The Conversion
Costs vary based on your approach. Here is a rough estimate.
- Bracket kit (Dana 35 or 8.25): $200-$400
- ZJ calipers and rotors: $100-$200
- Brake hoses and hardware: $50-$100
- Parking brake cables: $50-$100
- Total bracket conversion: $400-$800
For a Ford 8.8 swap, costs are higher.
- Used Ford 8.8 axle: $150-$400
- Spring perches and hardware: $50-$100
- Welding supplies or shop labor: $100-$300
- New rotors and pads: $100-$150
- Brake line adapters: $20-$50
- Parking brake cables: $100-$200
- Total axle swap: $500-$1200
Prices vary by region and parts condition. Shop around for deals. Junkyards are good sources for ZJ and Ford parts.
Frequently Asked Questions
Can I use Grand Cherokee parts for my XJ conversion?
Yes. ZJ Grand Cherokee rear calipers and rotors are common for bracket kits. They bolt up with the right brackets. Make sure to get parts from a 1993-1998 ZJ with rear discs.
Do I need to change the proportioning valve?
Not always. Many XJs work fine with the stock valve. If you get rear lockup, install an adjustable proportioning valve. Start with less rear bias and adjust from there.
Will a rear disc conversion improve my XJ’s braking?
Yes, significantly. You will get better fade resistance and a firmer pedal. Stopping distances decrease, especially under heavy load or off-road. It is one of the best upgrades for an XJ.
How long does the installation take?
A bracket kit takes 4-6 hours for a DIYer. The Ford 8.8 swap takes 8-12 hours including welding. Add time for bleeding and adjustments. Plan a weekend for the axle swap.
Do I need special tools for the parking brake?
Basic hand tools are enough. You may need a cable cutter for custom cables. A drill and small bits help if you modify brackets. Most kits include all needed hardware.
Final Thoughts On The Upgrade
A Jeep Xj Rear Disk Brake Conversion is a rewarding project. It makes your Cherokee safer and more enjoyable to drive. The parts are affordable and widely available.
Whether you choose a bracket kit or an axle swap, the results are the same. Better stopping, less maintenance, and improved off-road performance. Take your time with the installation and bleed the brakes properly.
You will notice the difference immediately on your first test drive. The pedal feels solid and the rear brakes bite consistently. No more fading after a long descent or a muddy trail.
If you have been thinking about this upgrade, now is the time. Gather your parts, set aside a weekend, and get to work. Your XJ will thank you with years of reliable service.