RCB S1 GRT PREMIUM ALLOY REAR BRAKE PUMP 14MM

RCB S1 GRT Premium Alloy Rear Brake Master Cylinder 14mm is a race-grade, high-performance hydraulic upgrade engineered to replace standard factory rear brake pumps.

As part of RCB’s flagship S1 Premium Series, this rear master cylinder features an upgraded 14mm internal piston bore wrapped in a ultra-durable billet alloy chassis. This configuration is specifically designed to displace a higher volume of brake fluid with less mechanical foot pedal travel, providing sportbikes, naked streetfighters, and track-day motorcycles with a sharp, immediate, and highly communicative rear braking response.

Key Features

• Upgraded 14mm Piston Bore: Features a larger internal diameter compared to standard 11mm or 12mm OEM pumps. This increases the hydraulic leverage and fluid displacement, delivering a firm, highly responsive brake pedal feel and eliminating “mushy” or spongy pedal feedback.

• Premium Billet Alloy Construction: Enclosed in a rigid, CNC-machined premium aluminum alloy housing. The monoblock-style design eliminates body flex under hard emergency or track-entry braking, ensuring that 100% of your foot pressure is transferred directly to the rear caliper pistons.

• Integrated/Universal Fit Bracket: Designed with an adjustable mounting slot layout. This versatile design allows the pump to easily line up with the rear master cylinder mounting bosses on a wide variety of factory rear-sets and aftermarket racing footpegs.

• Enhanced Thermal Stability: Built using race-derived, high-grade internal seals and return springs that maintain a consistent hydraulic pressure seal, even when exposed to extreme radiant heat radiating from low-slung exhaust pipes or hard-working rear disc rotors.

• Premium Anodized Armor Finish: Treated with a deep, corrosion-resistant anodized layer (available in premium shades like Gold, Red, Black, and Silver) to lock out moisture, road grime, and harsh chemicals while adding a distinct racing aesthetic to your foot controls.

Technical Specifications

Performance Benefit: Why Upgrade to 14mm?

Most factory motorcycles come equipped with small-bore rear pumps to prevent novice riders from easily locking up the rear wheel. However, for track racing, stunt riding, or motorcycles upgraded with multi-piston aftermarket rear calipers (like 2-piston or 4-piston RCB or Brembo calipers), a stock pump cannot push enough fluid efficiently. The 14mm bore provides the heavy-duty hydraulic volume required to feed performance calipers, giving you effortless one-touch braking modulation.

Installation Guidelines

1. Check Pitch Alignment: Measure the distance between the mounting bolts on your motorcycle’s rear-set. While the S1 GRT features universal mounting slots, ensure your specific bike layout accommodates a high-volume performance pump.

2. Use Fresh Fluid: Thoroughly flush out old, contaminated brake fluid from the lines and refill the system using a premium, unsealed bottle of DOT 4 or DOT 5.1 brake fluid.

3. Bleed the System Thoroughly: Because the 14mm piston moves fluid rapidly, air bubbles can sometimes hide in the banjo bolt joints. Bleed the system from the rear caliper upward until all air is fully evacuated and the foot pedal feels rock-solid.

4. Secure Fasteners: Apply a drop of medium-strength blue threadlocker (e.g., Loctite 242) to the mounting bolts to ensure that constant engine and road vibrations do not back the hardware out over time.