Replacing Hydraulic Line

The hydraulic lines in a hydraulic braking system may fail at one point or another. Due to the high pressure inside these lines, it is not possible to easily repair a broken line using simple techniques and often, the entire line must be completely replaced. This document covers replacing a hydraulic brake line. The sample brake used is a Magura HS-22.

1. Razor blade
2. New hydraulic line
3. Metric wrench set or cresent wrench
4. Metric allen wrench set
5. Vise grip
6. WD-40 (or other lubricant)
7. Safety glasses
8. Work gloves
9. Wire gripper (picture)

1. Identify the slave and the master side of the brake. The slave is the side where there is only one hydraulic line going into it (see Figure 1)
   
   Figure 1: Rear view of bike showing slave brake

2. Remove the broken hydraulic line. These lines are attached to the nipples very well. The nipple is actually barbed so that it won't slide off. The easiest way to do this is to cut the hydraulic line at the nipple so that it splits. You can then remove the line (be sure to be wearing safety glasses).
3. Cut a new length of new hydraulic line. Be sure to use a razor blade on both sides and cut perpendicular to the length of line (to create a clean right angle at the ends).
4. Remove the slave side brake set. Remember that this is the side with the bleeding bolt as shown below in Figure 2.
   
   Figure 2: Slave brake showing nipple and bleeder bolt

5. Remove the nipple from both the slave brake and the master brake (still on the frame) using metric wrench.
6. Secure nipple in vise grip with barbs facing up. DO NOT GRIP NIPPLE BY THREADS!!!
7. Spray nipple barbs and inside of hydraulic tube with WD-40.
8. Using wire gripper, press hydraulic tube onto nipple barbs. This will take a lot of work, be careful to only press down straight as shown below in Figure 3 (If you press at an angle, the hydralic line will bend). Be sure to wear gloves and goggles as it may slip.

   Nipple in vise

   Pressing line into nipple

   
   Figure 3: Pressing hydraulic line onto nipple

9. Repeat for second nipple. Finished hydraulic line should look like Figure 4.
   
   Figure 4: Hydraulic line with nipples

10. Screw line back into master side of brake.
11. Screw the slave brake (still free from frame) onto nipple. Make sure that you spin the slave brake around the nipple (the nipple should not be spinning).
12. Mount slave brake back onto frame. You are now ready to refill the hydraulic fluid and bleed the system.