BMW AP Racing Rear Big Brake Kit Explained

When it comes to enhancing the performance of a BMW, particularly for those who enjoy spirited driving or regular track days, upgrading the braking system is often a top priority. The AP Racing Big Brake Kit for the rear of specific BMW M models offers a significant leap in stopping power, heat management, and overall driving confidence. This article delves into what makes this kit a compelling choice for discerning BMW owners, focusing on its engineering, benefits, and compatibility.

Understanding the AP Racing Rear Big Brake Kit

The Rear AP Racing Big Brake Kit is meticulously engineered for a range of popular BMW M models, including the F87 M2, M2 Competition, F80 M3, F82 M4, and the E9X M3. Its primary purpose is to provide a substantial upgrade over the factory rear braking setup, delivering superior performance, especially under demanding conditions such as track use.

Key Features and Engineering Excellence

This kit is not merely a cosmetic upgrade; it's a performance-driven component designed for maximum effectiveness. Here's a breakdown of its core features:

• Calipers: The kit typically features AP Racing's renowned Radi-CAL four-piston calipers (CP9449 or CP9450 models). These calipers are celebrated for their stiffness, lightweight construction, and exceptional heat dissipation properties. The Radi-CAL design enhances rigidity, leading to a more consistent and responsive pedal feel.
• Discs: It includes 355x32mm brake discs. These are larger and often vented differently than OEM discs, allowing for greater heat absorption and dissipation. The larger surface area provides more material to resist fade during prolonged braking. J-Hook discs are also an available option, offering further improvements in cooling and pad cleaning.
• Weight Savings: A significant benefit of this kit is its weight reduction. It typically saves approximately 5kg compared to the OEM rear brakes. This unsprung weight reduction contributes positively to the car's overall handling, acceleration, and braking dynamics.

Performance Benefits for Your BMW

The advantages of fitting an AP Racing Big Brake Kit to the rear of your BMW are multifaceted:

• Superior Stopping Power: The combination of larger discs and more powerful calipers results in significantly increased stopping force. This translates to shorter braking distances and greater driver confidence, especially when pushing the car to its limits.
• Enhanced Heat Resistance: Track driving generates immense heat in the braking system. AP Racing components are designed to withstand these extreme temperatures, significantly reducing the risk of brake fade – that dangerous loss of braking performance due to overheating.
• Improved Pedal Feel: The stiffness of the AP Racing calipers and the quality of the components lead to a firmer, more consistent brake pedal. This allows for better modulation and control during braking.
• Balanced Braking System: This rear kit is specifically designed to complement AP Racing front brake kits, ensuring a balanced braking system. A well-balanced system prevents the rear brakes from being overwhelmed and ensures optimal weight transfer during deceleration.

Compatibility and Integration

One of the critical aspects of any brake upgrade is ensuring it integrates seamlessly with the existing vehicle systems. The AP Racing Rear Big Brake Kit excels in this regard:

• OEM Parking Brake Functionality: Crucially, this kit retains full OEM parking and hand brake functionality. This means you don't sacrifice everyday usability for track-focused performance.
• Master Cylinder and ABS Compatibility: The pistons within the calipers are precisely sized to work harmoniously with the OEM master cylinder and the car's Anti-lock Braking System (ABS). This ensures that the brake bias remains correct and the ABS system functions as intended, maintaining the safety and reliability of the vehicle.

Why Choose AP Racing?

AP Racing is a globally recognised leader in high-performance braking systems. Their products are used in virtually every form of motorsport, from Formula 1 and NASCAR to GT racing and rallying. This extensive experience translates directly into the quality and performance of their road-going kits.

Choosing AP Racing signifies a commitment to:

• Innovation: Constant development and a focus on cutting-edge technology.
• Quality: Manufacturing to the highest standards using premium materials.
• Performance: Proven results in the most demanding environments.

Important Considerations Before Purchase

While this kit offers substantial benefits, there are a few points to keep in mind:

• Brake Pad Selection: Brake pads are not included with the kit. However, a wide variety of high-quality options are available from leading manufacturers such as Endless, Dixcel, and Ferodo, allowing you to tailor the braking characteristics to your specific needs (e.g., track-focused pads vs. more street-friendly options).
• Lead Times: These kits are often made to order. It's essential to confirm stock availability and be aware of potential lead times, which can be up to 5 weeks. It's advisable to message the supplier to get the most accurate information regarding availability.
• Caliber Finish and Environment: If opting for nickel-plated calipers, it's important to note that they are not salt resistant. Owners in regions with harsh winters or frequent use in wet, salty conditions should be mindful of this to prevent corrosion.
• Matching Front Kit: For a truly balanced and optimal braking system, it is highly recommended to pair this rear kit with a suitable AP Racing front brake kit. A popular matching front kit is the AP Racing CP9660 BMW F8X/E9X Pro 5000R Race Kit.

Comparative Table: OEM vs. AP Racing Rear Kit (Illustrative)

The table below provides a general comparison. Specific weight savings and performance figures can vary slightly based on the exact OEM components and the specific AP Racing kit configuration.

Frequently Asked Questions (FAQ)

Q1: Will this kit fit my BMW F87 M2?
Yes, this specific kit is designed for the F87 M2, M2 Competition, F80 M3, F82 M4, and E9X M3 models.

Q2: Do I need to upgrade my master cylinder?
No, the kit is engineered for seamless integration with the OEM master cylinder, maintaining proper brake balance.

Q3: Can I use this kit for daily driving?
Absolutely. The kit retains OEM parking brake functionality and is designed to work with the ABS system, making it suitable for both road and track use.

Q4: What brake pads should I use?
Brake pads are not included, but reputable options from Endless, Dixcel, and Ferodo are recommended and available. Your choice will depend on whether you prioritise track performance or road comfort.

Q5: What is the typical lead time for this kit?
These kits are often made to order, and lead times can be up to 5 weeks. It's best to confirm availability with the supplier.

Q6: Is the nickel-plated finish suitable for winter driving?
Nickel-plated calipers are not salt resistant. If you frequently drive in winter conditions with road salt, consider an alternative finish or take extra precautions to clean and protect the calipers.

Conclusion

The AP Racing Rear Big Brake Kit represents a significant performance upgrade for BMW M cars. By offering superior stopping power, exceptional heat resistance, weight savings, and crucial integration with OEM systems, it provides a compelling solution for owners seeking to elevate their driving experience, particularly on the track. When paired with a matching front kit, it forms the cornerstone of a truly formidable and balanced braking system, ensuring you can brake later, harder, and with greater confidence.