1/8 Npt X 10mm Brake Line Adapter Fitting

Brake Line Adapter Fitting - 1/8" NPT Male to 10mm x 1.0 Metric Bubble Flare Female

Bridge the gap between aftermarket hydraulic components and your factory German plumbing with the 1/8" NPT to 10mm x 1.0 Metric Adapter from Appletree Auto. This specialized fitting is essential for Volkswagen enthusiasts who are installing accessories like staging brakes, line locks, or brake pressure gauges that utilize standard American 1/8" NPT ports. It features a 1/8" NPT male thread on one end and a 10mm x 1.0 female metric bubble flare seat on the other, allowing you to thread your original VW hard lines directly into your new performance hardware.

Precision-machined from high-strength materials, this adapter is designed to handle the extreme hydraulic pressures required for safe and consistent braking. It eliminates the need for expensive custom-made lines or difficult re-flaring of your existing brake system. Whether you are building a high-performance Sand Rail or upgrading a classic Baja Bug, Appletree Auto provides the professional-grade transition fittings needed to ensure your custom brake system is both secure and leak-free.

Product Fitment & Compatibility

This adapter is designed for vehicles using M10x1.0 metric bubble flare brake lines (the standard for air-cooled Volkswagens) and adapts them to components with 1/8" NPT ports.

• Volkswagen Beetle (Standard & Super): All Years (Equipped with M10x1.0 lines)
• Volkswagen Karmann Ghia: 1956 - 1974
• Volkswagen Bus / Transporter (Type 2): 1950 - 1979
• Volkswagen Thing (Type 181): 1973 - 1974
• Volkswagen Type 3: 1961 - 1973
• Custom Sand Rails & Dune Buggies: All years utilizing VW-style metric brake systems

Tech Tips & Installation Advice

• Dual Sealing Methods: It is important to remember that this fitting seals differently on each side. The 1/8" NPT side uses tapered threads to create a seal, while the 10mm side relies on the mechanical "crush" of the Bubble Flare seat.
• Use NPT Sealant: For the 1/8" NPT male side, we recommend a small amount of high-quality thread sealant or brake-fluid-resistant Teflon tape. This is necessary because NPT threads require a sealant to remain airtight under pressure.
• No Sealant on the Metric Side: Do not use Teflon tape or sealant on the 10mm x 1.0 female threads. The seal is formed by the metal-on-metal contact of the brake line's bubble flare against the internal seat. Adding sealant here can prevent the flare from seating properly and may contaminate your brake fluid.
• Verify Flare Type: Ensure your brake line is a true "Bubble Flare" (European style). This fitting is not compatible with American "Inverted Flares." Using the wrong flare style will lead to a high-pressure leak that cannot be stopped by tightening.
• System Bleeding: Any time you break a hydraulic connection, air enters the system. After installing this adapter, you must perform a full brake bleed. Start at the wheel furthest from the master cylinder to ensure all air is purged, restoring a firm and safe brake pedal.