I pieced my disc brakes together with old parts. I recommend buying a kit. Not being a seasoned mechanic like some of the folks here I found myself returning to the auto parts store numerous times to get more parts I didn't think of. Without instructions, I installed some things improperly too. With the help of a competent mechanic I got the system working well with one major glitch. The Grand Prix combination valve I chose to use is not proportioned correctly for my car and the rears lock too easily. This winter, I'm going to an adjustable proportioning valve. Unless you're better than me, go with a complete kit.