How to Flare Brake Lines

Flaring a brake line is an important process that makes sure your brake line has a leak-proof connection. Flaring makes the brake line tubing wider at the end, which in turn makes it so the connection can easily slip in deeper to guard against any potential leaks. Below, we take a look at how to properly flare a brake line using a brake tube flaring tool.

Step #1: Setup

The first thing to do is prepare the brake line tubing. Square cut the end of the tube using any suitable tubing cutter. Next, chamfer the outside of the tube and plunge the inside of the tubing to remove any burrs and remaining metal chips. Clean the outside of the tubing before placing it into the jaws of your brake tube flaring tool. Lightly apply a anti-seize compound lubricant to the end of the cut tubing, and then place the appropriate fittings over the ends of the tube with the flare end facing outward.

To set up the flaring tool, place the 1-1/2 inch by 1-1/2 inch square offset base of the tool, opposite the clamp, into a secure vice. Now, place the rotating die head onto the 1-1/4 inch round boss, which is adjacent to the lever base. Make sure that the die head is completely secured by snapping it over the ball detent to the side. Once the head is secure, place the 11 inch foam-grip handle into the hole in the lever base. Snap the handle into the ball detent firmly, pull the clamp pin out to release the clamp and rotate the clamp upward. Once that is done, you have set up your flaring tool and are ready to start flaring your brake line tube.

Step #2: Operation

First, choose the split die size that you need to flare to. Then, insert the dies both into the rectangular cavity in the base of the tool with the beveled counterbore end toward the die head and in the back end firmly against the step. Place your brake line tube in between the die halves with the tube completely flat, making sure that the end of the tube lines up with the split dies. Now, rotate the die head so that the flat-faced die (OP.O die) is facing the end of the tube. Move the lever inward towards the body utilizing the OP.O die as a stop gauge. Rotate the clamp back into place, and push the clamp pins back through the holes to lock the clamp to the tool. Tighten the threaded retainer screw in the clamp firmly against the die set, and turn the die head so that the corresponding die size lines up with the end of the brake line tube.

Now, move the lever against the tool body creating exerting enough energy to form the flare, continuing until the lever stops. You have now created a bubble flare. To create a 45 degree double flare, turn the die head so that one of the two appropriately sized dies lines up with the end of the tube. Move the lever once again against the body of the tool until it stops. Finally, loosen the threaded retainer screw, pull the clamp pin out, remove the split dies and take out your professional-quality flared brake line tube from the dies. You have now successfully created a 45 degree double flare tube.

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