Brake Line Fittings — DIN/SAE Standard

Brake line fittings provide the high-pressure pneumatic and hydraulic connections that transmit braking force from master cylinder to wheel cylinders or calipers in automotive, motorcycle, and light-truck brake systems. Brass brake line fittings have largely been replaced by steel in OEM production due to galvanic corrosion concerns with steel brake tubing, but brass remains widely used in motorsport, restoration, and aftermarket applications where corrosion resistance and ease of field-flaring outweigh galvanic considerations. We supply both bubble-flare (DIN/ISO style — the European OEM standard, used by most German, French, Italian, and Japanese vehicles) and double-flare (SAE style — the North American legacy standard, used by US-built domestic vehicles through the 1990s). Both flares are formed in the field using a brake-line flaring tool; our fittings include the appropriate male nut and seat geometry to match. Tube sizes are 3/16", 1/4", 5/16", 3/8", 7/16", and 1/2" OD — with 3/16" being the dominant residential automotive size for brake and 5/16" common for fuel lines. Working pressure is 3,000 PSI continuous, 10,000 PSI burst — far above brake-system operating pressures (typically 1,500-2,500 PSI under hard braking). Threads are SAE inverted-flare on the North American specification (UNF threads with a flat seat for the flare to seat against) or DIN-style metric for European applications. We offer male and female nuts, straight unions, tees, crosses, and adapter pairs for mixed-flare systems. C36000 brass standard, with C37700 available for higher fatigue resistance in motorsport applications.