Brake Line Unions – Leak-Proof, Rust-Resistant Connections
4Lifetime offers durable tube-to-tube brake line unions in 3/16", 1/4", and 5/16" sizes. Built to withstand extreme temps, resist corrosion, and ensure a secure, lasting seal—perfect for any brake system repair.
How to Pick the Right Brake Line Union
1. Match the tube size. A union joins two lines of the same diameter — 3/16" on most vehicles, 1/4" or 5/16" on others. Measure the outside diameter of your existing line before ordering.
2. Match the thread and style. Inverted-flare unions — like 3/16" with 3/8-24 threads, 1/4" with 7/16-24 threads, or metric M10x1.0 — require flared tube ends. Compression unions grip the bare tube instead, so no flaring tool is needed.
3. Pick the material. Brass seals easily and won't rust; stainless steel unions offer maximum corrosion resistance for harsh climates.
