For anyone replacing their own brake lines, knowing how to properly flare them is a must. Flared connections are essential for maintaining an airtight seal that keeps contaminants out of the brake system. The following gives a few tips on flaring your own brake line tubing.

Have the Right Tools

You will need a brake flaring tool. There are a variety of different tools on the market, from cheap manual flaring tools to expensive hydraulic-powered tools that make a broad range of flares. For most applications, you’ll just need a simple flaring tool capable of making single and double flares.

When it comes to cutting your brake line to size, a proper tubing cutter offers the best results. Other methods, like using a hacksaw or rotary cutting tool, can leave uneven cuts that lead to poor flares. You’ll also need a file or a tapered reamer to deburr the brake line tubing shortly after cutting. Some tubing cutters will have a built-in file just for this purpose.

Know the Right Techniques

Once you have the tools needed to make a proper flare, you’ll need to know what type of flare your brake line project calls for:

  • Single flares, where the brake line is flared out only once, are common on low-pressure brake systems but not usually recommended for use on modern high-pressure brake systems.
  • Double flares are common on modern domestic vehicles and recommended for high-pressure brake systems.
  • Bubble flares are common on European and Asian vehicles. They look similar to double flares. In fact, it doesn’t take much effort to turn a bubble flare into a double flare.

Once you have your tools ready, follow the steps below to properly flare your brake lines:

  1. Use the tubing cutter to cut the brake line tubing to the desired length.
  2. File down any leftover burrs from the inside diameter of the line. Use compressed air to blow out any cutting debris.
  3. Place the brake line fitting over the tube prior to flaring, otherwise, it’ll be impossible to slide the fitting over without cutting off the existing flare.
  4. Insert the brake line into the flaring tool, making sure that the end of the line barely pokes above the flaring base. For double flares, make sure the line barely reaches the height of the flaring anvil.
  5. Use the appropriate flaring die to flare out the brake line end. Be careful not to use too much pressure, as this can cause the flare to split apart.
  6. Repeat the above for the other end of the brake line.

Practice Leads to Perfection

Achieving the perfect flare takes time and practice, so don’t be disheartened if your first few efforts don’t go as planned. The best way to get good at flaring your own brake lines is to grab a few lengths of inexpensive brake line and start flaring. Once you have the technique mastered, you can confidently flare brake lines for your own vehicle.