When replacing brake lines, pre-fabricated lines are ideal, but often, you’ll need to create flares. The two main types are double flares and ISO flares (also called bubble flares). A double flare is folded back on itself, while an ISO flare is a single bubble shape. A specialized OTC kit can create both. Tools needed include a tubing bender, cutter, file, and reamer.

The process for a double flare involves cutting and reaming the line, chamfering it with a file, then using a flaring bar and yoke to create two stages of the flare.

For an ISO flare, you cut and deburr the line, then use the flaring bar with a special adapter to create a single bubble shape.

Both types of flares require practice. Crucially, compression fittings are not acceptable for brake line repairs; only ISO flares, double flares, or manufacturer-approved pre-fabricated lines are safe. Using corrosion-resistant lines is also essential.