How to Change Rear Brake Calipers

Upgrading your vehicle's braking system can be one of the most rewarding modifications you can make. Not only does it improve safety, but it also enhances the driving experience, especially for performance-oriented vehicles. While many focus on the front brakes, the rear brakes play a crucial role in overall stopping power and stability. If you're looking to replace worn-out rear brake calipers or fit some high-performance units, this guide will walk you through the process. We'll cover the necessary tools, safety precautions, and step-by-step instructions to ensure you can tackle this job like a pro. Remember, when it comes to brakes, precision and care are paramount.

Choosing Your Rear Brake Components

Before diving into the installation, it's essential to select the right parts for your vehicle. Whether you're replacing standard components or opting for an upgrade, quality is key. For this guide, we'll assume you're fitting high-performance EBC BSD rotors and EBC Yellowstuff pads, a popular choice for fast road use. These are direct replacement parts, meaning they are designed to fit your existing setup without modification. However, the principles discussed here apply to most vehicles with common brake configurations, such as single-piston floating calipers. Some vehicles might feature multi-piston floating calipers, or even more complex multi-pot fixed calipers found on performance models like RS Audis or Subarus. While the general procedure remains similar, fixed calipers may require removing pads from the top and have a slightly different approach due to the absence of separate caliper carriers.

Understanding Caliper Types

The majority of everyday cars and many performance vehicles utilise floating calipers. These consist of a caliper body that slides on pins, and a separate caliper carrier that bolts to the hub. The pads are typically housed within the caliper body or the carrier. Fixed calipers, on the other hand, have multiple pistons directly opposing each other and do not slide. They are generally found on higher-performance vehicles and often require a different method for pad replacement, usually involving removing the pads from the top of the caliper before the rotor can be accessed.

Essential Tools and Equipment

To successfully change your rear brake calipers and associated components, you'll need a comprehensive set of tools. This includes:

• Jack and axle stands
• Wheel brace
• Socket set (including various metric and imperial sizes)
• Spanners (including open-ended and ring spanners)
• Large hex keys or sockets (for some caliper bolts)
• Pry bar or large flathead screwdriver
• Wire brush
• Brake cleaner
• Torque wrench
• Nitrile gloves
• Safety glasses
• Brake piston winding tool (crucial for rear calipers)
• Copper grease
• Impact driver (optional, but recommended for stubborn rotor screws)
• Hammer (for stubborn rotors)

Safety First: The Golden Rules of Brake Work

Working on brakes is a critical task, and safety should always be your top priority. Never compromise on safety. Here are the essential precautions:

• Work on a level surface: Always park your vehicle on a flat, stable surface.
• Secure the vehicle: Use a reliable jack to lift the car and always support it with sturdy axle stands. Ensure the stands are placed on strong chassis points.
• Chock the wheels: Place wheel chocks on the wheels that remain on the ground to prevent the vehicle from rolling.
• Wear protective gear: Always wear safety glasses to protect your eyes from brake dust and fluid, and nitrile gloves to protect your skin from brake dust and chemicals.
• Brake fluid reservoir: Locate the brake fluid reservoir under the bonnet. Remove the cap to allow for easier piston retraction and to prevent pressure build-up. Be mindful of the fluid level; if it's too high, you may need to siphon some out.
• Component identification: Ensure you have the correct replacement pads and rotors for your specific vehicle model. If the new parts don't match the old ones in shape and size, you have the wrong parts.

Step-by-Step Guide: Changing Rear Brake Calipers and Rotors

Let's get started with the actual process. This guide focuses on a typical floating caliper setup, common on many vehicles.

1. Preparation and Wheel Removal

With the vehicle safely supported on axle stands, use your wheel brace to loosen the wheel nuts on the wheel you'll be working on. Once loosened, fully remove the wheel to expose the brake assembly.

2. Caliper Removal

Before you can remove the caliper, you'll need to disconnect it from the caliper carrier. Look at the back of the caliper. You'll typically find two retaining bolts that hold the caliper body to the carrier. These bolts often have dust covers that need to be removed first. Depending on your vehicle, these bolts might require a socket, spanner, or a large hex key. On some vehicles, you may also need an open-ended spanner to hold the bolt head stationary while you undo the nut, or vice versa, to prevent the entire assembly from spinning.

Once the retaining bolts are removed, the caliper body should be free from the carrier. You might need to use a pry bar or a large screwdriver to gently lever it off. Be careful not to damage the caliper itself or the brake hose. Many calipers have electronic pad wear sensors. If yours does, carefully unplug these before fully removing the caliper. Note the position of the pads within the caliper or carrier for refitting. Do not let the caliper hang freely by the brake hose, as this can damage the hose. Support the caliper using an axle stand, a piece of wire, or a dedicated caliper hanger.

3. Rotor/Disc Removal

The caliper carrier is usually mounted to the hub and often obstructs the removal of the brake rotor. Locate the bolts securing the caliper carrier to the hub assembly. These typically require a socket. Undo these bolts and remove the caliper carrier. Once the carrier is off, the rotor should be able to slide off the hub. However, on some vehicles, the rotor is secured to the hub by a small screw. This screw can be very tight and is prone to stripping. If you have an impact driver, this is the ideal tool for removing it. If not, use a manual screwdriver with firm pressure. If the rotor is still stubborn, a few well-placed taps on the back with a hammer can help break it free.

4. Hub and Rotor Cleaning

Before fitting the new rotor, it's crucial to clean the hub mating surface thoroughly with a wire brush and brake cleaner. This ensures the new rotor sits perfectly flat, preventing runout and potential vibration issues. A clean surface is essential for optimal performance and longevity.

5. Fitting the New Rotor

Give your new rotor a good spray with brake cleaner to remove any protective coating or manufacturing oils. This coating can impair braking performance if not removed. Carefully slide the new rotor onto the cleaned hub. Ensure it is correctly oriented if it's a directional rotor (check for any markings or V-grooves indicating direction). Re-fit the caliper carrier, ensuring the mounting bolts are tightened to the manufacturer's specified torque. If your rotor was secured with a screw, refit it, again being careful not to overtighten or strip it.

6. Piston Retraction

This is where the rear brake caliper differs significantly from the front. For rear brakes, the caliper piston(s) often need to be rotated back into the caliper body, rather than simply pushed. This is because the rear caliper mechanism usually incorporates a way to engage the handbrake, which is often linked to the piston. You will need a specialist brake piston winding tool for this. Insert the correct adapter from the tool into the piston and turn it clockwise. You may need to apply some pressure, but it should retract smoothly. If the piston is very stiff or won't retract, it could indicate a seized caliper, which may need replacing. Ensure the brake fluid reservoir cap is still off during this process.

7. Fitting New Brake Pads

Clean the caliper carrier and the areas where the pads sit with a wire brush and brake cleaner. Take your new brake pads and identify which pad goes where. Some pads have specific wear sensors that need to be connected to the corresponding wiring on the vehicle. Ensure these are securely plugged in. If your car doesn't have a pad wear monitoring system, you may need to cut off the sensor wires. Before fitting the pads, apply a small amount of copper grease to the edges of the pads where they contact the caliper and carrier. This helps prevent squeaking and seizing. Be extremely careful not to get any grease on the friction surface of the pad or the rotor.

Slide the new pads into place. They should fit snugly but without excessive force. Re-fit the caliper body over the pads and onto the carrier. Make sure any metal retaining clips or anti-squeal shims are correctly positioned. Re-install the caliper retaining bolts and tighten them to the manufacturer's recommended torque setting. Over-tightening small bolts can lead to them snapping.

8. Final Checks and Bedding-In

Once the caliper is secured, replace the brake fluid reservoir cap. Before starting the engine, pump the brake pedal several times. You'll notice it will feel soft at first and then firm up as the pistons push out against the new pads. This is normal and ensures the system is primed. Check the brake fluid level and top up if necessary, using the correct type of brake fluid for your vehicle.

Bedding-in your new pads and rotors is a crucial step for optimal performance and longevity. Over the next 100-200 miles, avoid harsh braking. Instead, perform a series of moderate stops from around 40-60 mph, gradually increasing the intensity. Allow the brakes to cool between sets of stops. This process allows the pad material to transfer evenly onto the rotor surface, creating a uniform friction surface for maximum bite and preventing premature wear or glazing.

Frequently Asked Questions (FAQ)

Q1: Do I need to change the brake fluid when changing the calipers?

A1: While not strictly necessary, it's good practice to consider flushing and replacing your brake fluid, especially if it hasn't been done for a while. Old brake fluid can absorb moisture, reducing its boiling point and performance.

Q2: Can I push the rear brake caliper pistons back with pliers?

A2: No, for most rear calipers, you must use a piston winding tool. Using pliers can damage the piston seals and the caliper mechanism.

Q3: How do I know if my rear caliper is seized?

A3: If the piston is extremely difficult or impossible to retract with a winding tool, or if you notice the brake dragging or overheating during driving, the caliper may be seized and require replacement.

Q4: What is the torque setting for caliper bolts?

A4: Torque settings vary significantly between vehicle manufacturers. Always consult your vehicle's service manual or a reliable online resource for the correct torque specifications.

Q5: How long does bedding-in take?

A5: The bedding-in process typically takes around 100-200 miles of driving, incorporating several moderate braking applications.