I found this info on a classic Corvette web site. ********************************************************************************************************* Lets make a list of some of the things you will need for your brakes. If your master cylinder is under the floor and you're using a disc drum set-up, you will need to use a 10 lb. Residual valve for the rear drum brakes, and a 2 lb. Residual valve for the front disc brakes, these valves go between the master cylinder and the GM intermediate proportionate valve. Unless you have 4 wheel disc brakes then you need to eliminate the proportionate valve and use two 2-pound residual valves. A 1-inch bore master cylinder will also be needed for your disc/drum set-up. Here are the part numbers for master cylinders. The first one is a F**d master cylinder that exits toward the frame rail and that number is 10-1525. This master cylinder has a large and a small reservoir, the large reservoir is for the front disc brakes. The other master cylinder exits towards your transmission and that number is 10-1371. This master cylinder is a Corvette master cylinder and both reservoirs are the same size. How you tell the front from the back is by the port, the larger port is for the rear brakes. Keep in mind I use the word port and not reservoir. These part numbers should be good at any Carquest, Napa, AutoZone or Advanced Auto parts stores. If you happen to have your master cylinder on the firewall, then you will not need to use residual valves, only the proportionate valve, unless you are using four-wheel disc brakes.------------------------------------------------------------------------------------
Four-wheel disc brakes are a whole other ball game. One, they use 4 calipers, and because they use 4 calipers it takes a lot more brake fluid to operate this type of system. One of the more popular rear ends is the Lincoln Versaille; one because it has calipers and rotors and the other is that it is a 9-inch F**d. One of the problems you will find in using this rear end is that the emergency brake is part of the caliper. The reason that this can be a problem is that most street rodders don?t hook up the emergency brake. Hooking the cables to the emergency brake arm on the caliper is difficult. Usually because the brackets are missing or the street rodders don?t have the correct end for the cables. These calipers have to use the emergency brake to keep them in adjustment. By not using the emergency brake, the brake pads will eventually start to wear in an uneven pattern. This causes loss of stopping power. One of the first things that a customer will ask me is, I have 4 wheel disc brakes, when I first installed them they worked real well, now they have slowly gotten worse. Not hooking up and using the emergency brake, which helps adjust the rear calipers, cause this. Just hooking up the emergency brake will not ensure that the calipers will adjust themselves, you will need to use your emergency brake at all times. Actually, it is recommended when you first install this system you need to pull and release the emergency brake at least 150 times, before using the brakes.-------------
The second problem that arises when using 4 wheel disc brakes is bore size of the master cylinder. Because 4-wheel disc brakes hold so much brake fluid, it takes a bigger bore master cylinder to stop the car. This master cylinder would have a 1-1/8 inch bore. This master cylinder gives you the volume but without using a power booster you don?t have the strength in your leg to stop the car. Some rodders will drop down in bore size to one inch, this will help somewhat in the fact that it makes it easier to stop the car, but the trouble with this is the pedal travel is almost to the floor before the brakes engage.
