VTT F9X M5/M8 Ultimate Lightweight Rear Brake Kit

F90 M5 / F91 M8 / F92 M8 / F93 M8

36.8 lbs off the rear. 18.4 lbs saved per side. 17″ wheel fitment. OEM BMW calipers. Factory electronic parking brake retained. 12.15″ two-piece vented rotors.

The VTT F9X M5/M8 Ultimate Lightweight Rear Brake Kit was engineered to remove a massive amount of unsprung and rotating mass while preserving the factory functionality that makes the car usable on the street.

Don’t confuse this with a stripped-down, single-purpose drag brake conversion.

The rear of the F9X presents a different engineering challenge from the front. The factory rear calipers incorporate the electronic parking brake, making it difficult to reduce brake weight without sacrificing factory functionality.

The VTT F9X Ultimate Lightweight Rear Brake Kit takes a different approach.

Using 12.15″ two-piece vented rotors with lightweight billet aluminum hats, F9X-specific VTT mounting components, and OEM BMW rear calipers, we’ve removed 36.8 lbs from the rear axle while retaining the factory electronic parking brake.

The complete VTT rear brake assembly weighs just 21.3 lbs per side, compared with 39.7 lbs per side for the factory assembly.

That is an 18.4-lb reduction at each rear corner.

Less brake weight.
Less rotating mass.
Smaller and lighter wheel options.
More tire options.
More traction potential.
Factory electronic parking brake retained.
Real braking capability.

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36.8 LBS OFF THE REAR

The factory F9X rear brake assembly weighs approximately 39.7 lbs per side.

The complete VTT rear brake assembly weighs just 21.3 lbs per side.

That means the VTT conversion removes:

• 18.4 lbs per rear corner
• 36.8 lbs across the rear axle

This weight is removed directly from the rear suspension and brake assemblies.

Removing 36.8 lbs from the rear of any performance vehicle is significant.

Removing 36.8 lbs of unsprung and rotating brake mass is even better.

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18.4 LBS SAVED PER SIDE

The weight difference at each rear corner is substantial:

• Factory rear brake assembly: 39.7 lbs
• VTT rear brake assembly: 21.3 lbs
• Weight reduction per side: 18.4 lbs

Across both rear corners, that becomes a total reduction of 36.8 lbs.

This reduction is achieved without eliminating the OEM BMW caliper or factory electronic parking-brake system.

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TWO-PIECE ROTORS REDUCE ROTATING MASS

The VTT system replaces the heavy factory rear rotor with a 12.15″ two-piece vented rotor featuring a lightweight billet aluminum hat.

The two-piece rotor design removes weight from the rotating brake assembly while retaining the vented construction needed for a heavy, extremely fast street and drag vehicle.

Because the rotor rotates with the wheel, weight removed here reduces both unsprung mass and rotating mass.

Rotating mass must be accelerated in two ways:

• Forward with the vehicle
• Rotationally around the axle

Reducing rotational inertia means less energy is required to accelerate the brake, wheel, and tire assembly.

For a vehicle being optimized for acceleration, response, and elapsed-time reduction, this is exactly where you want to remove weight.

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RETAINS THE OEM BMW REAR CALIPER

The rear of the F9X presents a unique challenge because the caliper assembly incorporates the electronic parking-brake system.

Many lightweight rear brake conversions eliminate factory functionality in pursuit of the lowest possible weight.

We didn’t want to do that.

Instead, VTT designed the rear conversion around the OEM BMW rear caliper.

That means the conversion retains:

• Factory electronic parking-brake operation
• OEM BMW rear caliper function
• OEM serviceability
• Street-friendly convenience
• BMW system integration

You get the weight reduction and wheel clearance of a purpose-built performance brake package without giving up the factory electronic parking brake.

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17″ REAR WHEEL FITMENT CHANGES EVERYTHING

For serious F9X performance builds, this may be one of the biggest advantages of the entire conversion.

The VTT F9X rear brake kit allows fitment of 17″ rear wheels.

The massive factory brake package severely limits wheel diameter and, as a result, limits the wheel and tire combinations available for the car.

The VTT system removes that limitation.

Dropping down to a 17″ rear wheel opens up a huge range of performance-oriented combinations, including:

• Lightweight drag wheels
• Drag radials
• Bias-ply tires
• Full slicks
• Taller-sidewall tire combinations
• Purpose-built drag racing wheel and tire packages

This gives F9X owners far greater freedom to optimize the car around weight, traction, tire construction, sidewall, and overall drag-strip performance.

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THE WEIGHT SAVINGS CAN GO FAR BEYOND 36.8 LBS

The 36.8-lb reduction comes from the rear brake conversion alone.

Once the factory brakes are no longer dictating wheel diameter, you can take the weight reduction significantly further.

Replacing the large, heavy factory rear wheel and tire combination with a lightweight 17″ drag setup can remove even more rotating and unsprung mass from the rear axle.

The VTT rear brake kit doesn’t simply save 36.8 lbs.

It unlocks the ability to remove additional rotating mass through your wheel and tire selection while dramatically expanding your available tire options.

More sidewall.

More tire choices.

More traction options.

Less rotating mass.

None of it is possible if the factory brakes won’t fit inside the wheel.

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NOT A SINGLE-PASS DRAG BRAKE KIT

Weight reduction is easy if you’re willing to sacrifice braking capability and factory functionality.

We weren’t.

F9X M5 and M8 models are heavy vehicles, and modified examples are capable of extraordinary horsepower, acceleration, and trap speeds.

That’s why the VTT rear kit uses substantial 12.15″ vented rotors and OEM BMW rear calipers rather than a minimal non-vented rotor and stripped-down caliper arrangement designed primarily around making a single pass.

The goal was straightforward:

Remove as much weight as possible without giving up the braking system and factory functionality required for a fast, heavy car.

The system is suitable for:

• Street driving
• Drag racing
• High-performance street use
• Moderate track use when properly configured and operated

You get the wheel clearance and weight reduction normally associated with a drag brake conversion while retaining a substantial vented rotor, OEM BMW calipers, and the factory electronic parking brake.

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COMPLETE BOLT-ON SYSTEM

The VTT F9X Ultimate Lightweight Rear Brake Kit is a complete bolt-on conversion designed specifically for the F9X platform.

The kit includes:

• VTT 12.15″ two-piece vented rear rotors
• VTT CNC-machined billet aluminum rotor hats
• OEM BMW rear calipers
• Factory electronic parking-brake actuators
• VTT CNC-machined F9X-specific caliper brackets
• Required mounting hardware
• Wheel spacers shown with the package, where applicable

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FITMENT

Designed specifically for the BMW F9X M5/M8 platform:

• F90 M5
• F91 M8
• F92 M8
• F93 M8

Wheel clearance varies according to wheel design, barrel profile, width, and offset.

Always confirm wheel fitment before purchasing wheels.

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THE BOTTOM LINE

The VTT F9X Ultimate Lightweight Rear Brake Kit isn’t simply about installing smaller brakes.

It’s about removing one of the biggest limitations of the factory F9X rear brake and wheel package.

• 36.8 lbs of rear brake-system weight removed
• 18.4 lbs saved per rear corner
• VTT assembly weighs 21.3 lbs per side
• Factory assembly weighs 39.7 lbs per side
• 12.15″ two-piece vented rotors
• Lightweight billet aluminum rotor hats
• Reduced rotating mass
• OEM BMW rear calipers retained
• Factory electronic parking brake retained
• 17″ rear wheel fitment
• Access to lightweight drag wheels, drag radials, and slicks
• Additional rotating-mass reduction potential through wheel and tire selection
• Street and drag capability

Drop the weight. Open up your wheel and tire options. Add traction. Keep the factory parking brake. Keep real braking capability.

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IMPORTANT DISCLAIMER

VTT HD brake kits are designed for street use and drag racing, with moderate track use when properly configured with the appropriate pad compound and operated within the capabilities of the system.

Always operate your vehicle within your abilities and the capabilities of the braking system.

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BEDDING PROCEDURE - CRITICAL

Brake pads must be properly bedded to achieve full braking performance.

Failure to properly bed the pads can result in dramatically reduced braking effectiveness and pad glazing.

If glazing occurs:

• Remove the affected components as necessary.
• Properly prepare or sand the pad friction surface.
• Reinstall the components.
• Repeat the complete bedding procedure before demanding maximum braking performance.

Do not judge the braking capability of the system before the pads have been properly bedded.

Complete bedding instructions are included with every VTT brake kit.