Recommended Additional Upgrades
01
S1 FL 30th Anniversary Special Edition
Get the Combo set for the ultimate brake system upgrade.
The RCB S1 Alloy Brake Fluid Tank Cap is a premium CNC-machined replacement for the standard plastic reservoir caps found on S1/S1-FL Master Brake Pumps. As part of the S1 Series, it is designed for riders who prioritize high-end finishing and durability.
Beyond the aesthetic upgrade, this cap provides a more rigid seal for the brake master cylinder, ensuring the hydraulic system remains pressurized and free from moisture contamination.
Key Features
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CNC Machined Billet Aluminum: Carved from a solid block of high-grade aluminum, offering significantly more strength and heat resistance than factory plastic caps that can warp or crack over time.
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Leak-Proof Precision: Designed to fit perfectly with the original rubber diaphragm (gasket). The precision threading ensures a tight seal, preventing corrosive brake fluid from leaking onto your paintwork or fairings.
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Deep Anodized Coloring: Features a high-gloss, UV-resistant anodized finish. Unlike painted parts, this color is chemically bonded to the metal, ensuring it won’t peel or fade even when exposed to harsh brake fluid or direct sunlight.
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S1 Signature Styling: The cap features the iconic RCB S1 geometric patterns and branding, providing a sophisticated “cockpit” view for the rider.
Technical Specifications
| Feature | RCB S1 Tank Cap Details |
| Material | T6 Billet Aluminum Alloy |
| Series | S1 (Performance & Styling) |
| Finish | Anodized (Red, Gold, Blue, Black, Silver) |
| Compatibility | Universal Round 15ml Fluid Tank |
| Installation | Direct Screw-on Replacement |
Why Upgrade to the RCB S1 Cap?
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Chemical Resistance: Brake fluid (DOT 3, 4, or 5.1) is highly corrosive. Plastic caps can eventually become “chalky” or brittle due to chemical exposure. The T6 alloy remains unaffected.
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Visual Consistency: If you have already installed RCB S1 Master Cylinders or Clutch Levers, this cap completes the uniform look of your handlebar controls.
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Durability: In the event of a minor tip-over or impact, a plastic cap is prone to shattering, which can disable your brakes by letting air into the system. An alloy cap provides a much higher level of protection.
Installation Note
When swapping the cap, use a clean cloth to wipe away any excess brake fluid from the rim of the reservoir before installing the new cap. Ensure the internal rubber diaphragm is seated flat; if the diaphragm is twisted, the system will not seal correctly, leading to “spongy” brake feel.
