BMW M2 / M3 / M4 F80 F82 F83 F87 – BTCC Big Brake Kit – AP Racing CP9660 Complete Upgrade | XC3 Engineering

XC3 Engineering BTCC Big Brake Kit – BMW F80 M3, F82/F83 M4 & F87 M2

Unlock serious braking performance with the XC3 Engineering BTCC Big Brake Kit for the BMW F80 M3, F82/F83 M4 and F87 M2.

Built around the proven AP Racing CP9660 6-piston Pro 5000 Series R caliper and genuine ex-BTCC 368mm x 36mm brake rotors, this complete front brake conversion is designed for demanding fast-road, track-day and motorsport use.

The F8X M platform combines significant power, relatively high vehicle weight and strong tyre performance, placing substantial thermal demands on the front braking system during repeated hard use.

The XC3 BTCC Big Brake Kit addresses this with increased thermal capacity, stronger braking performance, improved pedal consistency and genuine motorsport hardware adapted specifically to the BMW F8X chassis.

Why Upgrade Your BMW F8X Brakes?

The BMW F80 M3, F82/F83 M4 and F87 M2 are extremely capable performance cars, but repeated heavy braking during track use can place substantial stress on the factory system.

As power, tyre grip and braking intensity increase, brake temperatures rise rapidly.

This can contribute to:

• Reduced braking consistency
• Increased pedal travel
• Accelerated pad and rotor wear
• Higher brake fluid temperatures
• Brake fade during sustained circuit use

The XC3 BTCC Big Brake Kit provides a more capable braking platform through larger motorsport rotors, AP Racing calipers, race pads and braided brake lines.

Key Features

• Complete front big brake conversion
• Designed for BMW F8X M cars with OEM front hubs
• AP Racing CP9660 6-piston Pro 5000 Series R calipers
• Genuine ex-BTCC 368mm x 36mm brake rotors
• XC3 Engineering custom CNC-machined rotor bells
• XC3 Engineering custom caliper carriers
• AP Racing floating disc bobbin hardware
• Braided brake lines
• Raybestos ST45 ex-BTCC brake pads
• Project Mu H21 pads available as an alternative
• Increased thermal capacity
• Strong, repeatable braking performance
• Designed for track-day, clubsport and fast-road use

AP Racing CP9660 6-Piston Calipers

At the heart of the system are AP Racing CP9660 Pro 5000 Series R 6-piston calipers.

The CP9660 is a motorsport-focused caliper developed for high-performance applications where stiffness, consistent pad pressure and reliable braking response are critical.

Its 6-piston layout distributes clamping force across a large race pad, helping provide strong and predictable braking under repeated heavy use.

For track-focused F8X builds, the CP9660 offers a substantial step beyond conventional road-car braking hardware.

Genuine Ex-BTCC 368mm x 36mm Rotors

The kit uses genuine ex-BTCC 368mm x 36mm brake rotors.

These rotors are sourced from British Touring Car Championship use and are not a standard retail rotor size typically available to the public.

The rotors supplied with the kit have previously been used during a single BTCC event session before being removed from competition use.

Each rotor is inspected before supply to confirm that it remains in suitable working condition.

Using lightly used BTCC components allows this kit to deliver genuine motorsport braking hardware at a considerably more accessible cost than an equivalent all-new competition system.

XC3 Engineering CNC-Machined Rotor Bells

The BTCC friction rings are paired with custom XC3 Engineering anodised rotor bells.

These are CNC machined specifically to adapt the motorsport rotor to the BMW F8X front hub arrangement.

The bells are designed to provide the correct interface between the hub, AP Racing bobbin hardware and 368mm friction ring.

The anodised finish provides a high-quality appearance and additional surface protection.

XC3 Engineering Caliper Brackets

Custom XC3 Engineering anodised caliper carriers are used to position the AP Racing CP9660 calipers correctly around the 368mm rotors.

The carriers are precision machined for the BMW F8X application and supplied with Chemi Black mounting hardware.

Correct caliper positioning is essential when adapting motorsport brake hardware to a production vehicle, making these vehicle-specific carriers a critical part of the conversion.

Floating Motorsport Rotor Assembly

The kit includes AP Racing bobbin hardware to connect the friction rings to the rotor bells.

The floating arrangement allows the rotor to expand as temperatures increase during repeated hard braking.

This helps manage the thermal stresses generated during circuit use and is commonly used in high-performance and motorsport braking systems.

For heavily tracked vehicles, this also makes replacement of the friction rings more straightforward once they reach the end of their usable life.

Braided Brake Lines

Braided brake lines are supplied as part of the conversion.

Compared with conventional rubber hoses, braided lines are designed to reduce hose expansion under hydraulic pressure.

This can contribute to a firmer and more consistent pedal feel, particularly when brake system temperatures increase during repeated high-load use.

Raybestos ST45 Brake Pads

The standard kit is supplied with ex-BTCC Raybestos ST45 brake pads.

Like the rotors, these are previously used motorsport components selected to help keep the overall package cost-effective.

Raybestos ST45 is a well-established racing compound suited to repeated heavy braking, track days, clubsport and endurance-style use.

Typical characteristics include:

• Consistent mid-to-high friction
• Predictable pedal response
• Strong modulation
• Stable performance through repeated hard braking
• Operating capability up to approximately 700°C rotor temperature
• Relatively rotor-friendly behaviour for a race compound

For mixed fast-road and track use, ST45 offers a strong balance between performance, consistency and consumable wear.

Optional Project Mu H21 Brake Pads

Project Mu H21 pads are also available as an alternative.

Please contact us if you would prefer the kit supplied with H21 pads.

The H21 is a more aggressive competition-focused compound intended for demanding high-temperature motorsport use.

Typical characteristics include:

• Strong initial bite
• High fade resistance
• Stable high-temperature friction
• Approx. 200°C–850°C operating range
• Motorsport-focused performance
• Suitable for repeated high-load braking

For dedicated track cars, Time Attack builds or competition vehicles where maximum braking performance is the priority, H21 may be the more appropriate choice.

Raybestos ST45 vs Project Mu H21

The best pad choice depends on how the car is used.

Raybestos ST45 is generally the better option for drivers looking for:

• Predictable braking
• Strong modulation
• Consistent track performance
• Reasonable consumable life
• Mixed road and circuit use

Project Mu H21 is more heavily focused on competition.

It offers a more aggressive braking response and greater high-temperature capability, making it better suited to:

• Dedicated track cars
• Time Attack builds
• Race cars
• Sustained high-temperature use
• Drivers prioritising maximum bite and fade resistance

For a road-driven F8X car that sees regular track days, ST45 will generally be the more versatile option.

For a dedicated circuit build, H21 may offer greater performance.

Used BTCC Rotor & Pad Information

Please be aware that both the standard brake rotors and Raybestos ST45 pads supplied with this kit are previously used motorsport components.

The rotors have typically been used during a single BTCC event session before being removed from competition use.

They are inspected prior to supply and only supplied when considered to be in usable condition.

The standard pads are also used items.

This approach helps keep the cost of the complete brake system considerably lower while still giving customers access to genuine competition-specification hardware.

Signs of previous heat cycling, surface marking and cosmetic wear should therefore be expected.

Cost-Effective Replacement Rotors

One of the biggest long-term advantages of this BTCC-based brake kit is replacement rotor cost.

Motorsport brake consumables can become expensive, particularly on heavy, powerful cars running high-grip tyres.

The ability to replace worn friction rings with lightly used ex-BTCC 368mm x 36mm rotors can significantly reduce ongoing running costs compared with equivalent new motorsport discs.

This makes the kit particularly attractive for drivers who use their F8X M car regularly on track.

Built for the BMW F8X Platform

The F8X M cars place substantial demand on the braking system.

The platform combines:

• Turbocharged power
• High straight-line performance
• Significant vehicle weight
• Large tyre contact patches
• High cornering speeds
• Strong track-day capability

All of these factors increase the amount of energy the braking system must repeatedly convert into heat.

The XC3 BTCC kit is designed to provide the thermal capacity and consistency needed for this type of use.

BMW F87 M2

The F87 M2 is lighter and more compact than the M3 and M4, but modified cars can still place significant demands on the brakes.

Higher power, semi-slick tyres and frequent circuit use can quickly expose the limits of the standard system.

The AP Racing CP9660 and 368mm BTCC rotor combination provides a strong foundation for fast-road and track-focused F87 builds.

BMW F80 M3

The F80 M3 combines substantial turbocharged performance with a capable rear-wheel-drive chassis.

For cars seeing regular track use, increasing braking thermal capacity can improve consistency over repeated laps.

The XC3 BTCC kit provides a motorsport-derived solution designed around the demands of high-performance use.

BMW F82 / F83 M4

The F82 M4 Coupe and F83 M4 Convertible share much of their braking and chassis architecture with the F80 M3.

The BTCC conversion is particularly suitable for modified M4 builds running additional power, higher-grip tyres or regular track sessions.

Exact vehicle and hub specification should always be confirmed before ordering.

Ideal for Track-Day & High-Performance Builds

The XC3 BTCC Big Brake Kit is particularly well suited to:

• BMW F87 M2 track builds
• BMW F80 M3 track builds
• BMW F82 M4 performance builds
• BMW F83 M4 applications where compatible
• Higher-powered F8X M cars
• Cars running semi-slick tyres
• Clubsport builds
• Time Attack vehicles
• Fast-road cars that see regular track use

As power and grip increase, braking capability becomes increasingly important for maintaining repeatable performance.

Wheel Clearance

Due to the large 368mm rotors and AP Racing CP9660 calipers, wheel clearance must be checked before ordering.

Compatibility depends on:

• Wheel diameter
• Wheel width
• Wheel offset
• Spoke profile
• Internal barrel clearance

Wheel diameter alone does not guarantee caliper clearance.

If you are unsure whether your wheels will clear the kit, please contact us before ordering.

Brake Fluid

For track use, the brake system should be paired with a suitable high-temperature performance brake fluid.

Brake fluid should also be replaced regularly on vehicles that see frequent circuit use.

Even a high-performance brake kit can suffer from inconsistent pedal feel if the brake fluid exceeds its operating range.

Professional Installation

Professional installation is strongly recommended.

Installation should include:

• Caliper carrier installation
• Rotor bell and friction ring assembly
• Brake line installation
• Correct hardware torque procedures
• Brake system bleeding
• Wheel clearance checks
• Pad and rotor inspection

The braking system is safety critical and should only be installed by a competent technician.

Made to Order

XC3 Engineering BTCC Big Brake Kits are made to order.

We aim to keep the individual components available wherever possible, but certain parts may occasionally be subject to a lead time.

Please contact us before ordering if you require confirmation of current availability or have a specific deadline.

Fitment

Designed for applicable BMW F8X M cars using OEM front hubs, including:

• BMW F87 M2
• BMW F80 M3
• BMW F82 M4
• BMW F83 M4

Exact fitment should be confirmed against the vehicle specification before ordering.

If you're unsure whether this kit is suitable for your BMW, contact us and we'll be happy to help confirm compatibility.

Kit Contents

The XC3 Engineering BTCC Big Brake Kit includes:

• 2x AP Racing CP9660 Pro 5000 Series R 6-piston calipers
• 2x ex-BTCC 368mm x 36mm brake rotors
• XC3 Engineering custom anodised rotor bells
• XC3 Engineering custom anodised caliper brackets
• Chemi Black bracket hardware
• Braided brake lines
• 2x AP Racing bobbin kits
• Ex-BTCC Raybestos ST45 brake pads

Project Mu H21 brake pads are also available as an alternative. Please contact us for this option.

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