The flexible hoses which connect the steel brake lines with the rear brakes and front calipers must be checked for cracks, chafing, leaks, blisters, etc every six months. Original equipment and aftermarket steel and flexible brake lines can be purchased in part store, service parts department from an auto dealer among other auto parts stores. When putting in the brake line it is critical that not less than 3/4 of an inch between the line and other parts that are movable or vibrate. To remove a hose and line, one has to use a flare-nut wrench to loosen a brake line-to-hose fitting and undo the clip as well as shifting the hose out of the bracket. Where two hoses mating is involved, you should not use impact wrenches on the hose fittings but normal wrenches only, after undoing the two hoses, ensure that the two are not twisted or strained in any way. Most steel brake lines are clipped in place along their length and these clips, which should first be removed to enable the withdrawal of a fixed brake line, should always be reapplied or replaced if required because they assist in preventing vibration which may ultimately cause failure of the brake line. When you have to replace brake lines, use the correct one and never use copper tubing and get the steel brake lines from dealer or auto parts store. Make sure that a steel line does not have any of its portion in close contact with moving or hot parts and such part of the steel line is firmly fixed on the brackets. Following the installation of the master cylinder, check the brake master cylinder fluid level, put in some more fluid if needed, do a brake bleeder, and examine the brakes and then take the vehicle for a spin to check on the brakes in traffic.