Stainless Steel Brake Lines install 02-07 WRX/STi:

4.) Loosen the flair nut on the solid line with a 10mm flair nut wrench. Only use flair nut wrenches for this. If you use a regular wrench you will most likely strip the nut. Which will become a massive pain for you if it ruins the hard lines. Once, it is loose clip it with a a locking pliers to minimize how much brake fluid comes out. Keep an eye on the level in the brake fluid reservoir, because you do not want it to get so low as to empty it out which will cause air bubbles to be introduced into the brake lines and ABS system. You will be able to do all 4 lines w/ minimal loss fluid loss. You should never have to add fluid until it becomes time to bleed them. However, it is best to check and keep the level up by adding fluid if needed.

5.) Next use a 12mm wrench to loosen the banjo bolt at the caliper. Tighten it back to minimize the fluid loss.

6.) Use a flat blade screwdriver to remove the clip holding the flex line to the solid line. It just slides out. After the clip is off  unscrew the flair nut from the flex line then undo the banjo bolt. Be ready for a flood of brake fluid out of the caliper. Put a large shallow pan  under the brakes when you do this. Make sure the old washer from the banjo bolt is not stuck to the caliper. You don’t want to put two on the same side.

7.) Fit the new stainless steel brake lines in place. The banjo bolt has a copper washer on each side. It goes together the same way it came apart. Notice that the new stainless steel brake lines’s banjo bolt had a slight angle to it. The angle faces away from the caliper. Secure the line to the strut with the 12mm bolt. Slide the bracket on the new line that mounts to the strut to get it to match up. Care must be taken that the new line isn’t kinked. When you put the solid line to the new flex line the hex end will fit into the slots on the mounting bracket. It may be necessary to loosen the flair nut to rotate the flex line so it isn’t touching the car anywhere. The stainless steel brake lines need to flex up and down and not rub up against anything.