At XC3 Engineering, we don't just design for the street; we bring professional motorsport technology to the enthusiast. Our BTCC-spec Big Brake Kits for the BMW M2, M3, and M4 (E9X & F8X) are built around the legendary AP Racing 368mm x 36mm Rotor architecture.
To keep your setup performing at a championship-winning level, understanding your consumables is key. Whether you're chasing lap times or maintaining a high-performance track weapon, here is the essential guide to the three pillars of your XC3 brake system maintenance.
1. The Core: AP Racing ex-BTCC Brake Rotors (368mm x 36mm)
The heart of our kit is the massive 368mm vented rotor. These aren't just "inspired" by racing, they are sourced directly from current BTCC teams.
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Why it Matters: These rotors feature the signature "J-Hook" design for improved initial bite and debris clearance.
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The XC3 Advantage: By utilising inspected, high-quality "ex-BTCC" rotors, we provide a professional-grade braking surface at a fraction of the cost of brand-new units. It’s the ultimate way to access elite-level heat management and stopping power without the typical motorsport price tag.
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Maintenance Tip: Always inspect for heat crazing and thickness. When it’s time to swap, these are a direct fit for our custom bells.
2. The Connection: AP Racing Rotor Bobbins (CP4135-107K12)
A floating brake system is only as good as the hardware that holds it together. These high-strength forged steel bobbins provide the vital link between the rotor ring and the bell.
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The Function: Professional racing rotors need to expand and contract under extreme thermal loads. These bobbins allow for proper "float," preventing the rotor from warping when you're late-braking into a hairpin.
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Strength & Precision: Using the correct CP4135-spec hardware ensures that your braking remains consistent, even when temperatures soar.
3. The Refinement: Anti-Rattle Bobbin & Clip Kits
True "race" brakes can be vocal. Because floating rotors have inherent clearance for thermal expansion, they can sometimes produce a mechanical "knock" during low-speed driving. For the driver who wants race performance with a more refined feel, we offer our Anti-Rattle solution.
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The Solution: This kit includes 12 specialised bobbins and anti-rattle clips.
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How it Works: By replacing every other bobbin on your rotors, you can significantly reduce the "clatter" of the floating assembly without sacrificing the rotor's ability to expand under heat.
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Compatibility: Designed for the "newer style" BTCC rotors (where the J-Hook pattern doesn't touch the edge of the rotor face).
Precision Engineered, Performance Driven
Whether you are replacing worn rotors after a season of track days or upgrading your hardware to quiet down your daily-driven car, XC3 Engineering has the components in stock to keep you on the road and on the track.
Need help with fitment? Check out our Installation Guides or contact us at info@xc3.co.uk.