The hydraulic brake lines from the master cylinder use a double wall steel tubing throughout the system with the exception of the flexible hoses at the front and rear wheels. When connecting a tube to a hose, tube connector, or brake cylinder, tighten the tube fitting nut to specifications using a flare wrench. These are available in different sizes at most automotive parts stores.
All models utilize the brake tubes with ISO flares and metric tube nuts at the master cylinder. These brake tubes are installed from the brake master cylinder to the left and right front brake hoses. The fittings at the master cylinder are either M10 or M12 metric tube nuts, where as the fitting at the front brake hoses are 3 / 8 in. or 3 / 16 in. tube nuts, used with a double flare.
When replacing a brake line, it is recommended that factory lines with machine flared ends be used. With these type lines, the connection are far superior. Also, with many factory brake lines, the line is pre-bent and therefore far easier to install.
Although factory brake line tubing is recommended, you can purchase hydraulic tubing and bend and flare the ends yourself. Refer to the section on flaring brake tubing for information on the procedure.
If brake tube replacement is required from the brake master cylinder to the left or right brake hose, the following procedure should be followed.
- Obtain the recommended bulk 3 / 16 in. steel tubing and correct standard 3 / 8 - 3 / 16 in. tube nut. The M10 and M12 metric nuts will be reused.
- Cut the tubing to the length required. Clean the burrs after cutting. The correct length may be obtained by measuring the removed tube using a string and adding 1 / 8 in. for each flare.
- Place the removed metric tube nut on the tube. ISO flare one end of the tubing using the ISO and double flare tool kit D81L2269A or equivalent.
- On the opposite end of the replacement tube, install a standard 3 / 8 - 3 / 16 in. tube nut and double flare tube end.
Be sure to follow the flaring instructions included in the ISO and double flare tool kit D81L2269A or equivalent.
- Using a bending tool of the correct diameter, bend the replacement brake tube to match the removed tube using a suitable tube bender. When the replacement brake tube is installed, maintain adequate clearance to all moving or vibrating parts.
If a section of brake tubing becomes damaged, the entire section should be replaced with tubing of the same size, shape, length and material. Copper tubing should not be used in a hydraulic system. When bending the brake tubing to fit the body contours, be careful not to kink or crack the tubing.
All brake tubing should be flared properly to provide a good leakproof connection. Clean the brake tubing by flushing it with clean brake fluid before installation. When connecting a tube to a hose, tube connector or brake cylinder, tighten the tube fitting nut to specifications with a suitable torque wrench.
Always bleed the applicable primary or secondary brake system after the hose or line replacement.
REMOVAL & INSTALLATION
- Drain the brake reservoir of any brake fluid.
- Using the correct size flare wrench, loosen the brake line.
Because the material used to construct brake tubing is thin metal, great care should be used when removing and replacing brake lines.
- Once the nut on the brake line is loose enough, finish loosening the nut by hand.
- Loosen the other end of the brake line, and remove the line.
- Clean any open connection in the brake system. Clean both ends of the new brake line. Use compressed air and blow out the line to make sure no foreign matter is in the line.
- Position brake line to open end of brake system. Begin fastening the nut by hand until tight.
Start any brake line nuts by hand to ensure that no nuts get cross threaded.
- Position and install the other end of the brake line in the same manner as done above.
- Tighten the nut.
- Fill brake reservoir with new brake fluid.
- Bleed brake system.
BRAKE PIPE FLARING
See Figures 1 and 2
Flaring steel lines is a skill which needs to be practiced before it should be done on a line which is to be used on a vehicle. A special flaring kit with double flaring adapters is required. It is essential that the flare is formed evenly to prevent any leaks when the brake system is under pressure. Only steel lines, not copper, should be used. It is also mandatory that the flare be a double flare. With the supply of parts available today, a pre-flared steel brake line should be available to fit your needs. Due to the high pressures in the brake system and the serious injuries that could occur if the flare should fail, it is strongly advised that pre-flared lines should be installed when repairing the braking system. If a line were to leak brake fluid due to a defective flare, and the leak were to go undetected, brake failure would result.
If this is the first time flaring a brake line, it is strongly recommended that you try flaring on a piece of metal line before actually flaring the line to be used on the vehicle.
- Determine the length of metal brake line needed. Allow 1 / 8 in. (3.2mm) extra for each flare. Cut the metal line using only a suitable pipe cutting tool.
- Square the end of the tube with a file and chamfer the edges. Remove any burrs.
- Install the required fittings on the metal tube.
- Install the flaring tool into a vise, and install the handle into the operating cam.
- Loosen the die clamp screw and rotate the locking plate to expose the die carrier.
- Select the required die set and install it in the carrier.
- Insert the prepared line through the rear of the die and push forward until the line end is flush with the die face.
- Make sure that the rear of both halves of the die are resting against the hexagon die stops. Then rotate the locking plate to the fully closed position and clamp the die firmly by tightening the clamp screw.
- Rotate the punch turret until the appropriate size points toward the open end of the metal line to be flared.
- Pull the operating handle against the metal line to create resistance in order to make the flare, then return the handle to the original position.
- Release the clamp screw and rotate the locking plate to the open position.
- Remove the die set and the metal line, then carefully separate by gently tapping both halves on the bench. Inspect the flare for the proper size and shape.