I am getting ready to swap from drums to disc on the front of my 72 A-body. I have power drums all the way around. My question is... is my booster "correct" for discs or is it different on discs', can i use my master cylnder? probably getting ahead of my self, just wondering. thanks for your feedback!
The booster is the same, be it drum or disc. The difference is the master cylinders and the push rod that goes between the booster and the master. The disc brake Master has a larger front reservoir to compensate for the fluid used to push the caliper pistons. Also, the master cylinder bores are bigger, again for all the fluid used to push the caliper piston. You can use your master cylinder as is, but you have to check the fluid more often, because of the fluid required for the front disc (Notice that almost everything different revolves around using more fluid to push the caliper pistons out). On my 67 Skylark, I swapped front disc brake spindles only, and had no problems with the master cylinder size or the proportioning valve. When I needed to replace the master cylinder, I upgraded to the front disc master, which is how I found out that the push rods are different lengths between drum and disc brake masters. Having the bigger bore on the disc brake master, it stops a lot easier, and with less effort at the pedal. In short, you can swap the front disc brakes onto your car and safely drive it with the master, booster and proportioning valve you currently have. -Josh
