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Brembo Brakes for Harley-Davidson: Complete Buying Guide
Brembo is one of the most recognized manufacturers of high-performance motorcycle braking systems. Known for its racing heritage, advanced caliper construction, and precision hydraulic components, Brembo offers braking solutions for riders seeking improved control, consistent lever feel, and premium construction.
At Get Lowered Cycles, we carry Brembo motorcycle brake calipers, RCS radial master cylinders, clutch master cylinders, replacement brake pads, and related hardware for Harley-Davidson custom applications.
Whether you're upgrading a performance Road Glide, building a Low Rider S, or assembling a custom Dyna or FXR braking system, understanding the differences between Brembo components is essential.
This buying guide covers the Brembo M4, GP4-RS, GP4-RX, and .484 calipers, along with RCS master cylinder technology, compatibility considerations, and important installation requirements.
Brembo Brake Calipers for Harley-Davidson
Brembo offers several radial-mount motorcycle brake calipers with different construction methods, piston sizes, finishes, and intended applications.
The models available at Get Lowered Cycles include:
| Brembo Caliper | Piston Diameter | Construction | Finish |
|---|---|---|---|
| M4 | 4 × 34mm | Cast aluminum monoblock | Black or titanium |
| GP4-RS | 4 × 30mm | Cast aluminum monoblock | Titanium Grey |
| GP4-RX | 4 × 32mm | Machined billet aluminum, two-piece | Nickel plated |
| .484 Cafe | 4 × 32mm | Machined billet aluminum, two-piece | Anthracite Black |
These specifications reflect the particular caliper configurations currently listed by Get Lowered Cycles.
All four product lines use radial mounting arrangements, but none should be assumed to bolt directly onto a particular Harley-Davidson model without confirming the complete braking system.
Brembo M4 Radial Mount Brake Calipers
The Brembo M4 is a popular option for performance-oriented Harley builds using compatible radial caliper mounting brackets.
Its monoblock body is manufactured from a single aluminum casting, creating a rigid caliper structure designed to provide consistent braking response.
The M4 features four 34mm pistons and a 108mm radial mounting bolt-center dimension.
Key specifications:
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Four 34mm caliper pistons
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Cast aluminum monoblock construction
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108mm radial mounting bolt centers
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22.5mm listed offset
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Approximately 800g per caliper without pads
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DOT 4 brake fluid specified
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Supplied with brake pads
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Available as individual left/right calipers or a pair
The M4 is available in two finishes.
Black with Red Lettering: A black finish with Brembo's contrasting red logo, suitable for darker performance builds.
Brembo M4 Radial Mount Caliper - Black
Titanium with Red Lettering: A contrasting metallic finish that complements exposed aftermarket suspension, wheels, and braking hardware.
Brembo M4 Radial Mount Caliper - Titanium
The M4 is worth considering when planning a custom radial-caliper conversion with appropriately matched hydraulic and mounting components.
Brembo GP4-RS Radial Brake Calipers
The Brembo GP4-RS brings MotoGP-inspired design features to a radial-mount caliper constructed from cast aluminum.
The GP4-RS uses four 30mm pistons and a monoblock design, offering a different hydraulic configuration from the M4.
Key specifications:
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Four 30mm pistons
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Cast aluminum monoblock body
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108mm radial mounting bolt centers
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22.5mm listed offset
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Titanium Grey finish
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Approximately 935g per caliper without pads
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DOT 4 brake fluid specified
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Supplied with sintered brake pads
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Left, right, and paired configurations available
The smaller piston diameter is an important factor when matching the caliper with a suitable master cylinder.
Changing caliper piston area affects hydraulic leverage and fluid displacement. The correct master cylinder depends on the total braking system, not simply whether the caliper can be mounted.
Shop Brembo GP4-RS Radial Calipers
Brembo GP4-RX Nickel-Plated Radial Calipers
The Brembo GP4-RX is a premium billet aluminum caliper featuring a distinctive nickel-plated finish.
Unlike cast monoblock calipers, the GP4-RX uses two precision-machined aluminum body sections joined mechanically.
The caliper uses four 32mm pistons, with internal hydraulic design and machining intended to provide precise and repeatable braking response.
Key specifications:
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Four 32mm caliper pistons
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Machined billet aluminum construction
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Two-piece caliper body
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Nickel-plated exterior
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108mm radial mounting bolt centers
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22.5mm listed offset
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Approximately 1,000g per caliper without pads
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DOT 4 brake fluid specified
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Supplied with sintered brake pads
The nickel-plated finish gives the GP4-RX a distinctive appearance that stands out on high-end custom motorcycles.
This caliper appeals to builders prioritizing precision-machined construction, premium finishes, and a race-inspired braking setup.
Shop Brembo GP4-RX Nickel-Plated Calipers
Brembo .484 Cafe Radial Calipers
The Brembo .484 Cafe is another billet aluminum radial-mount caliper, developed with a styling direction suited to premium custom and café-racer-inspired motorcycles.
Its name references the approximate cubic-inch displacement of an individual 32mm piston.
The caliper features an anthracite black finish and a machined two-piece aluminum construction.
Key specifications:
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Four 32mm caliper pistons
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Precision-machined billet aluminum body
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Two-piece construction
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Anthracite Black finish
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108mm radial mounting bolt centers
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22.5mm listed offset
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Approximately 720g per caliper without pads
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DOT 4 brake fluid specified
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Supplied with sintered brake pads
The .484 offers a different combination of construction, finish, and weight than the GP4-RX, despite both utilizing 32mm pistons.
Shop Brembo .484 Cafe Radial Calipers
Brembo M4 vs. GP4-RS vs. GP4-RX vs. .484
Choosing the correct Brembo caliper involves more than comparing appearance or price.
Brembo M4: Features four 34mm pistons and cast monoblock construction. A popular option for custom performance braking systems.
Brembo GP4-RS: Uses four 30mm pistons with cast monoblock construction and a titanium-colored finish.
Brembo GP4-RX: Features four 32mm pistons, a precision-machined billet body, and nickel plating.
Brembo .484 Cafe: Uses four 32mm pistons and billet construction with an anthracite finish and distinctive custom styling.
A caliper with larger pistons does not automatically deliver better overall braking performance. Master cylinder sizing, rotor dimensions, pad compound, tire traction, and system setup all affect the result.
For any custom Harley braking system, hydraulic compatibility and mounting geometry should determine component selection before appearance.
Brembo RCS Radial Brake Master Cylinders
The Brembo RCS radial brake master cylinder is designed to give riders control over lever feel through Brembo's Ratio Click System.
RCS stands for Ratio Click System, an adjustable lever mechanism that allows the rider to select between two lever ratios.
The patented mechanism uses an eccentric adjustment to change the lever pivot-to-pushrod distance between 18mm and 20mm.
Understanding the Brembo RCS 18mm vs. 20mm Settings
18mm Setting: Provides a more progressive, modulated lever response, with greater lever movement for a given hydraulic output.
20mm Setting: Produces a more immediate response and a firmer-feeling lever, with less mechanical leverage.
The adjustment changes lever geometry rather than the master cylinder's piston bore or the caliper's hydraulic characteristics.
This allows riders to fine-tune their preferred brake lever feel within the intended range.
Single-Caliper vs. Dual-Caliper Master Cylinders
Get Lowered Cycles offers Brembo RCS brake master cylinder options intended for different braking-system configurations.
These include separate single-caliper and dual-caliper selections.
Choosing the correct configuration depends on factors such as:
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Number of front calipers
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Total caliper piston area
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Caliper type and design
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Master cylinder piston diameter
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Brake line configuration
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Required lever travel and hydraulic pressure
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Applicable ABS system requirements
A master cylinder designed for one hydraulic configuration should not automatically be used with a different caliper arrangement.
The product also offers an optional 45ml reservoir kit.
Shop Brembo RCS Brake Master Cylinders
Brembo RCS Hydraulic Clutch Master Cylinders
Brembo also offers RCS radial clutch master cylinders for compatible custom hydraulic clutch systems.
Like the brake master cylinder, the clutch version is designed around a high-quality hydraulic actuation system with adjustable lever characteristics.
These products are intended for specific hydraulic clutch arrangements and must be matched with the correct clutch release components.
Important: Harley-Davidson motorcycles equipped with cable-operated clutches cannot use a hydraulic clutch master cylinder as a direct replacement without an appropriate hydraulic conversion.
Before purchasing, confirm compatibility with the clutch slave cylinder or release mechanism, hydraulic line fittings, fluid requirements, and the complete actuation system.
An optional 15ml reservoir kit is available with the clutch master cylinder listing.
Shop Brembo RCS Clutch Master Cylinders
Brembo Brake Pads & Replacement Hardware
Maintaining a performance braking system requires the correct replacement pads and hardware.
Brembo HH Sintered Brake Pads
Get Lowered Cycles carries Brembo C-Shape HH Sintered Replacement Brake Pads for specified Brembo radial calipers.
The product listing identifies compatibility with the M4, GP4-RS, GP4-RX, and .484 caliper families.
HH-rated sintered pads are designed to provide stable friction characteristics across a broad operating-temperature range.
They are commonly selected for motorcycles requiring predictable braking response under demanding conditions.
Always confirm the pad shape, part number, and caliper compatibility before ordering.
Shop Brembo HH Sintered Replacement Brake Pads
Brembo RCS Banjo Bolts
Brembo also manufactures dedicated hydraulic connection hardware for its master cylinders.
Get Lowered Cycles carries a single M10x1.0 banjo bolt listed for Brembo RCS brake master cylinder applications.
When replacing brake line hardware, verify the required thread pitch, banjo configuration, sealing washers, and tightening procedure.
Installing Brembo Brakes on a Harley-Davidson
Many Brembo brake components sold for Harley-Davidson motorcycles are intended for custom applications.
A radial-mount caliper does not necessarily replace a factory Harley-Davidson caliper without additional components.
Depending on the motorcycle, installation may require:
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Model-specific radial caliper mounting brackets
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Correctly sized front brake rotors
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Caliper spacers or offset adjustments
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Compatible rotor thickness and swept area
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Appropriate wheel and spoke clearance
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New brake lines and hydraulic fittings
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A matched brake master cylinder
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Compatible ABS plumbing and service procedures
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Properly specified installation hardware
Harley Touring and Performance Bagger Applications
Brembo components are commonly considered for performance bagger builds where riders are upgrading the front braking system.
For Road Glide and Street Glide applications, verifying wheel design, brake rotor dimensions, fork mounting arrangements, and ABS compatibility is particularly important.
Shop Harley Touring Brake Components
M8 Softail, Low Rider S, and Low Rider ST Applications
For Milwaukee-Eight Softail performance builds, radial-caliper conversions can be part of a larger brake and suspension upgrade.
The correct mounting bracket and rotor combination depends on the front fork, wheel, and original braking-system configuration.
Do not assume all Low Rider S, Low Rider ST, or other M8 Softail models share identical front brake mounting arrangements.
Harley Dyna and FXR Applications
Custom Dyna and FXR builds frequently involve different front-end combinations, including inverted forks, aftermarket wheels, and larger brake rotors.
These configurations require particular attention to caliper alignment, wheel clearance, and hydraulic compatibility.
The fact that a caliper uses 108mm radial mounting centers does not establish compatibility with every aftermarket fork or adapter.
Brembo Brakes Frequently Asked Questions
Are Brembo calipers direct bolt-on replacements for Harley-Davidson?
Not necessarily. Many Brembo radial calipers require model-specific mounting brackets, spacers, compatible rotors, and correctly matched hydraulic components.
What is the difference between Brembo M4 and GP4-RS calipers?
The Brembo M4 listed at Get Lowered uses four 34mm pistons, while the GP4-RS uses four 30mm pistons. Both are cast aluminum monoblock radial calipers, but they have different hydraulic characteristics and should be matched to appropriate master cylinders.
Are Brembo GP4-RX calipers billet aluminum?
Yes. The GP4-RX calipers listed at Get Lowered use precision-machined billet aluminum construction and a nickel-plated finish.
What is the difference between Brembo GP4-RX and .484 calipers?
Both use four 32mm pistons and machined billet aluminum construction in the versions we carry. They differ in body design, finish, and published weight.
What does RCS mean on a Brembo master cylinder?
RCS stands for Ratio Click System. It allows adjustment between 18mm and 20mm lever ratios to change braking response and lever feel.
Can a Brembo RCS master cylinder work with factory Harley calipers?
Compatibility depends on the exact master cylinder piston size, factory caliper configuration, and hydraulic system. Verify the complete system before selecting a master cylinder.
Do Brembo calipers work with ABS?
Compatibility depends on the specific motorcycle and hydraulic configuration. The calipers alone do not establish that a conversion will retain proper ABS operation. Any changes to an ABS-equipped system require appropriate components and service procedures.
What brake fluid do Brembo motorcycle calipers use?
The M4, GP4-RS, GP4-RX, and .484 calipers currently listed at Get Lowered specify DOT 4 fluid. Always follow the requirements of the complete hydraulic system, including the master cylinder, rather than selecting fluid based solely on the caliper.
Can I install Brembo brake calipers myself?
Brake system work is safety-critical. Installation requires correct alignment, compatible components, fastener procedures, hydraulic bleeding, and functional inspection. Professional installation is recommended when the motorcycle requires a custom brake conversion.
Shop Brembo Brakes & Master Cylinders at Get Lowered Cycles
At Get Lowered Cycles, we carry Brembo performance brake components for Harley-Davidson riders and custom motorcycle builders.
Explore Brembo M4, GP4-RS, GP4-RX, and .484 radial brake calipers, RCS brake and clutch master cylinders, HH sintered pads, and replacement hardware above.
Whether you're upgrading a performance bagger, building a custom Softail, or assembling a Dyna or FXR front end, selecting the right brake components is essential for predictable braking performance.
For additional components, explore our complete selection of Harley-Davidson Brake Parts.
Get Lowered Cycles offers free U.S. shipping on every order with no minimum purchase.
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