Upgrading Bullnose Ford Truck Brakes: Converting Rear Drum Brakes to Disc Brakes

The 1980-1986 Ford F-Series trucks, commonly referred to as the “bullnose” generation, are known for their durability and ruggedness. However, one area where these classic trucks show their age is in their braking system, particularly with the use of rear drum brakes. While drum brakes were standard for decades, modern disc brakes offer superior stopping power, better heat dissipation, and easier maintenance. This article will guide you through the process of upgrading your bullnose truck’s rear drum brakes to disc brakes, covering the benefits, suitable donor vehicles, the step-by-step procedure, and considerations for making the swap. We will also explore aftermarket options and high-performance disc brake setups for both the front and rear.
Why Do a Rear Disc Brake Swap?
Before diving into the specifics of the conversion process, it’s essential to understand why you might want to upgrade from rear drum brakes to disc brakes on your bullnose Ford truck.
1. Improved Stopping Power
- Disc brakes generally provide better stopping power than drum brakes, particularly under heavy braking conditions. This is because disc brakes have more consistent contact with the brake pad surface, leading to more effective braking.
2. Better Heat Dissipation
- Disc brakes dissipate heat more effectively than drum brakes, reducing the risk of brake fade during prolonged or intense braking. This is especially important for trucks that are used for towing, hauling heavy loads, or off-roading, where braking demands can be higher.
3. Easier Maintenance
- Disc brakes are generally easier to inspect and service compared to drum brakes. With disc brakes, you can easily check the condition of the pads and rotors without removing the entire assembly. Replacing worn components is also more straightforward.
4. Consistent Performance
- Disc brakes provide more consistent braking performance across different driving conditions, including wet weather. Drum brakes can be prone to reduced performance in wet conditions as water can get trapped inside the drum, affecting brake operation.
5. Modernization and Aesthetics
- Upgrading to disc brakes can modernize your truck’s braking system, bringing it more in line with current vehicles. Additionally, disc brakes, especially with performance rotors and calipers, can add a visually appealing touch to your truck.
Sourcing Rear Disc Brakes for a Bullnose Ford Truck
When converting from drum to disc brakes, you can source parts from later model vehicles that use rear disc brakes. The following vehicles are popular donors for rear disc brake conversions on bullnose Ford trucks due to compatibility and availability:
1. 1995-2001 Ford Explorer
- Compatibility: The 1995-2001 Ford Explorer is one of the most popular choices for a rear disc brake swap on bullnose Ford trucks. The rear axle assemblies from these vehicles are often a direct bolt-on or require minimal modification.
- What You Need: The entire rear axle assembly can be swapped, or you can harvest the brake components, including the calipers, rotors, backing plates, and parking brake components.
- Advantages: These axles often have the correct bolt pattern (5×4.5″) and gear ratios compatible with the F-Series trucks. Additionally, the Explorer rear axles often come with limited-slip differentials, which can be a bonus.
2. 1997-2003 Ford F-150
- Compatibility: Rear disc brake components from the 1997-2003 Ford F-150 can also be used for a conversion. While these trucks have a different bolt pattern (5x135mm), the brake components can still be adapted to fit a bullnose truck’s axle.
- What You Need: You can use the calipers, rotors, backing plates, and necessary hardware. Modifications may be needed to ensure proper fitment.
- Advantages: The components are more readily available, and the parts are designed for a truck, ensuring they are capable of handling the weight and load of an F-Series vehicle.
3. 1999-2004 Ford Mustang GT
- Compatibility: Rear disc brake components from a 1999-2004 Mustang GT can be adapted for use in a bullnose truck, especially if you are using an 8.8″ rear axle.
- What You Need: Calipers, rotors, and backing plates from the Mustang. Modifications to the axle or caliper mounting may be necessary.
- Advantages: The Mustang’s performance brakes are designed for high-speed, high-performance applications, making them a good choice for those looking to improve stopping power.
4. Aftermarket Kits
- Compatibility: Various aftermarket companies offer bolt-on rear disc brake conversion kits specifically designed for the Ford 9-inch or 8.8-inch axles, commonly found in bullnose trucks.
- What You Need: Most kits include calipers, rotors, brackets, and all necessary hardware. Some kits also include a master cylinder designed to work with disc brakes.
- Advantages: These kits are designed for ease of installation with minimal modifications required. They are also designed to work with the truck’s existing brake system, reducing the likelihood of compatibility issues.
Step-by-Step Procedure for Doing A Rear Disc Brake Swap
Converting from rear drum brakes to disc brakes requires several steps, including disassembly, fitting the new components, and ensuring everything is working correctly. Here’s a general overview of the process:
1. Preparation and Tools
- Tools Needed:
- Jack and jack stands
- Wrench set and socket set
- Torque wrench
- Brake line wrench
- Brake caliper tool
- C-clamp
- Hammer and punch
- Screwdrivers
- Brake fluid
- New brake pads and rotors
- Calipers and caliper brackets
- Backing plates (if needed)
- Parking brake cables (if needed)
- Safety Precautions:
- Ensure the vehicle is on a level surface and properly supported by jack stands.
- Wear protective gloves and eyewear.
- Depressurize the brake system by pumping the brake pedal several times with the engine off.
2. Remove the Rear Drum Brakes
- Remove the Wheels: Use a lug wrench to remove the lug nuts and take off the rear wheels.
- Remove the Brake Drums: Remove the brake drums by pulling them off the axle. If they’re stuck, use a hammer and punch to tap around the drum to loosen it.
- Disconnect the Brake Lines: Use a brake line wrench to disconnect the brake lines from the wheel cylinders. Be prepared to catch any leaking brake fluid.
- Remove the Drum Brake Assembly: Remove the brake shoes, springs, and hardware, followed by the wheel cylinders. You may need to remove the axle shafts to access all the components fully.
3. Install the Disc Brake Components
- Mount the Backing Plate: Install the new backing plate (if applicable) on the axle flange. This will provide the mounting points for the caliper and parking brake components.
- Install the Rotors: Slide the new brake rotors onto the axle hub. Ensure they are seated properly and rotate freely.
- Mount the Calipers: Attach the caliper brackets to the backing plate and mount the calipers. Ensure that the calipers are centered over the rotors and that the pads make even contact with the rotor surface.
- Connect the Brake Lines: Connect the brake lines to the new calipers using the appropriate fittings. You may need to fabricate or adapt the existing brake lines to fit the new components.
- Install the Parking Brake Cables: If your new setup includes parking brakes, connect the parking brake cables to the calipers or parking brake shoes. Adjust the cables as necessary to ensure proper operation.
4. Bleed the Brakes
- Bleeding Process: Start by bleeding the brakes to remove any air trapped in the system. Begin with the brake farthest from the master cylinder (usually the passenger-side rear) and work your way closer. Use a brake bleeder tool or have a helper pump the brake pedal while you open the bleeder valve to release air.
- Check for Leaks: Inspect all connections for leaks and ensure the brake pedal feels firm. If the pedal feels spongy, there may still be air in the system, and further bleeding is necessary.
- Tip: Use Speed Bleeders to make bleeding brakes quicker and easier, especially for a single person.
5. Test Drive and Adjustments
- Test Drive: After completing the installation, take the truck for a test drive to ensure the brakes are functioning correctly. Pay attention to how the brakes feel, any unusual noises, or pulling to one side.
- Final Adjustments: Make any necessary adjustments to the parking brake or calipers to ensure everything operates smoothly. Check the brake fluid level and top it off if needed.
Cost and Difficulty of the Disc Brake Swap
Cost:
Upgrading from drum brakes to disc brakes on a bullnose Ford truck (1980-1986) can vary in cost depending on whether you source parts from donor vehicles, opt for new or aftermarket components, and the quality of the additional parts needed. Here’s a general cost breakdown:
- Donor Vehicle Disc Brake Parts (rotors, calipers, spindles, etc.): $200 to $600, depending on condition and where they are sourced (junkyard vs. new).
- New or Aftermarket Brake Components (rotors, calipers, pads): $300 to $800, if you prefer new parts for reliability and performance.
- Master Cylinder (if upgrading): $50 to $150, necessary if your current master cylinder isn’t compatible with disc brakes.
- Proportioning Valve: $30 to $100, to adjust brake pressure between the front and rear brakes.
- Brake Lines and Hoses: $50 to $150, depending on whether custom lines are needed to accommodate the new setup.
- Miscellaneous Hardware (bolts, brackets, etc.): $20 to $50.
- Brake Fluid: $10 to $30.
- Professional Installation (if not DIY): $400 to $800, depending on labor rates and the complexity of the installation.
Overall, the total cost of the disc brake swap can range from $660 to $2,580 or more, depending on the parts used, whether you opt for professional installation, and any additional upgrades you choose to include.
Difficulty:
The difficulty of the disc brake swap is moderate to high, depending on your mechanical skills and experience with brake systems. The key factors affecting difficulty include:
- Mechanical Skills: Basic to advanced mechanical skills are required. You should be comfortable working on suspension and brake systems, as well as making any necessary modifications to ensure proper fitment.
- Tools and Equipment: You’ll need a good set of tools, including wrenches, sockets, brake line wrenches, a jack and jack stands, and possibly a brake bleeder tool. Access to a press or special tools may also be needed for certain components.
- Time Commitment: The swap can take a full day or more, depending on your experience level and whether any unforeseen issues arise.
- Potential Challenges: Challenges may include ensuring proper alignment and fitment of new components, bleeding the brakes effectively, and adjusting the proportioning valve to achieve balanced braking.
Given the complexity, the disc brake swap is a project that can be completed by experienced DIY enthusiasts. However, if you’re not confident in your abilities or lack the necessary tools, it might be wise to seek professional assistance to ensure the job is done safely and correctly.
Considerations for Swapping Rear Drum Brakes for Disc Brakes
While upgrading to rear disc brakes offers many benefits, there are several important considerations to keep in mind:
1. Compatibility
- Ensure that the donor parts or aftermarket kit are compatible with your specific axle and truck configuration. Mismatched parts can lead to poor performance or safety issues.
2. Brake Bias
- Converting to rear disc brakes may alter the brake bias (the balance of braking force between the front and rear wheels). You may need to adjust the proportioning valve or install an adjustable proportioning valve to optimize braking performance.
3. Master Cylinder
- Drum brake master cylinders are designed to work with the hydraulic characteristics of drum brakes. When converting to disc brakes, you may need to upgrade to a master cylinder designed for disc brakes to ensure proper brake fluid volume and pressure.
4. Parking Brake
- Ensure that the parking brake setup works correctly after the conversion. Many disc brake setups use a drum-in-hat or a mechanical caliper parking brake, and proper adjustment is crucial for functionality.
5. Wheel Fitment
- Disc brake conversions may affect wheel fitment, especially if larger calipers or rotors are used. Check for clearance between the brake components and the wheels, and consider upgrading to larger wheels if necessary.
Aftermarket Options for Rear Disc Brake Conversions
If sourcing parts from donor vehicles isn’t ideal for your project, several aftermarket companies offer rear disc brake conversion kits specifically designed for bullnose Ford trucks. These kits are often engineered for ease of installation and come with all the necessary components.
1. SSBC (Stainless Steel Brakes Corporation)
- Products: SSBC offers a range of rear disc brake conversion kits for Ford trucks, including kits for the Ford 9-inch and 8.8-inch rear axles. Their kits typically include rotors, calipers, brackets, and all necessary hardware.
- Advantages: SSBC kits are known for high-quality components and ease of installation. They are designed to work with your existing brake system, minimizing the need for additional modifications.
2. Wilwood Engineering
- Products: Wilwood offers high-performance rear disc brake kits designed for custom and high-performance applications. Their kits are available for various axle configurations and are popular among those building performance trucks.
- Advantages: Wilwood kits are engineered for maximum performance, offering superior stopping power and heat dissipation. They also offer options for larger rotors and multi-piston calipers.
3. Summit Racing
- Products: Summit Racing offers a variety of rear disc brake conversion kits, including options for Ford trucks. These kits are available at different price points, making them accessible for a range of budgets.
- Advantages: Summit Racing’s kits are a great option for those looking for a balance of performance and affordability. They also offer comprehensive customer support and installation guides.
High-Performance Disc Brakes for Front and Rear
If you’re looking to further enhance your bullnose Ford truck’s braking performance, upgrading both the front and rear brakes to high-performance disc brakes is an excellent option. High-performance brakes offer better stopping power, reduced fade, and improved durability, making them ideal for trucks used in demanding conditions.
1. Wilwood Front and Rear Disc Brake Kits
- Front Kits: Wilwood offers front disc brake kits that include larger rotors, multi-piston calipers, and performance brake pads. These kits are designed to improve stopping power and heat dissipation, making them ideal for trucks used in towing or off-roading.
- Rear Kits: Matching rear disc brake kits are available, allowing you to upgrade both axles for a balanced braking system. These kits are often used in conjunction with a proportioning valve to fine-tune brake bias.
2. Baer Brakes
- Front and Rear Kits: Baer Brakes offers high-performance front and rear disc brake kits designed for custom applications. Their systems feature large, cross-drilled, and slotted rotors, as well as multi-piston calipers for maximum performance.
- Advantages: Baer Brakes are known for their quality and performance, making them a top choice for those building show trucks or high-performance vehicles.
3. PowerStop Z36 Truck & Tow Brake Kit
- Front and Rear Kits: PowerStop’s Z36 Truck & Tow Brake Kit is designed specifically for trucks that tow or haul heavy loads. These kits include performance rotors and carbon-fiber ceramic brake pads that offer improved stopping power and reduced brake dust.
- Advantages: PowerStop kits are a more affordable option for those looking to upgrade both front and rear brakes without sacrificing performance.
Installation Considerations for High-Performance Brakes
- Cooling: High-performance brakes generate more heat, so consider adding brake cooling ducts or upgrading to high-temperature brake fluid to prevent fade.
- Proportioning Valve: When upgrading both front and rear brakes, it’s essential to ensure proper brake bias. An adjustable proportioning valve allows you to fine-tune the brake balance for optimal performance.
- Brake Lines: Consider upgrading to stainless steel braided brake lines, which offer better resistance to expansion under pressure, providing a firmer brake pedal feel.
Conclusion
Converting your bullnose Ford truck’s rear drum brakes to disc brakes is a worthwhile upgrade that offers improved stopping power, better heat dissipation, and easier maintenance. Whether you choose to source parts from donor vehicles like the Ford Explorer or opt for an aftermarket kit, the benefits of disc brakes are clear, especially for those who use their trucks for towing, off-roading, or daily driving.
By carefully selecting the right components, following the correct installation procedures, and considering performance upgrades for both the front and rear, you can significantly enhance the safety and performance of your classic truck. Whether you’re restoring your bullnose to its former glory or customizing it for modern performance, upgrading to rear disc brakes is a practical and impactful modification.
If you want more specific information on Bullnose Ford Trucks, check out my YouTube Channel!
For more information on Bullnose Trucks and Broncos, you can also check out the BullnoseFord SubReddit or Gary’s Garagemahal, both are excellent resources.