A decrease in master cylinder bore area produced a proportionate. The different bore sizes are directly related to the rest of your brake system.
Master Cylinder Brake Line Fitting Size Dodge Diesel
Master cylinder bore size chart. Most dirt track racers with a dual master cylinder set up choose to run the 78 bore master cylinder to the rear and the 1 bore master cylinder to the front. With a 34 inch bore master cylinder the piston area is 044 square inches and the pressure developed is 400 909 psi. 5 master cylinder bore too small creating excessive high line pressure. 044 the stroke to move 06 cubic inches of fluid is 064 14 inches. This master cylinder has a 1 bore and ports on the left hand side of the master cylinder which should work well for a 1969 mustang. By calculating the area in inches squared bore x bore x 785 for any master cylinder size you can calculate how much pressure change would be affected by a bore size change.
A 78 bore master cylinder has a bore area of 6 inches squared. In this case with the manual disc brakes both front and rear on the customers 69 mustang we recommend a 1 bore master cylinder specifically mpb part number mc11378m. Larger bore master cylinders move a high volume of brake fluid at lower pressure with less pedal travel. Most master cylinders have a bore size of 58 inch to 1 18 inch. The c4 calipers have a relatively small bore size so a relatively smally bore master cylinder matches up. A smaller bore moves less fluid at higher pressure with increased pedal travel.
If we apply that same 100 pounds of force to the 78 master cylinder using the formula 100 divided by 6 that same 100 pounds of force from the pedal will generate 1667 psi. The piston in the master cylinder is not being allowed to return to the full retract location when released. Stiffen master cylinder mounts brakes are locked up after run. You wont go wrong using the same bore size that was used on a stock c4. If fluid pressure at the caliper measures low reducing the master cylinders bore size will increase pressure and vice versa. This helps free the car up getting in the corner and allows the car to carry more speed into the corner.
044 as a general rule a person is able to exert approximately 150 pounds of pedal pressure 75 pounds of lever pressure and 50 pounds of grip pressure. 6 master cylinder deflection. Match master cylinder to system. The larger piston like the one used in the legend series calipers typically require a master cylinder with a larger bore size while the smaller but multi piston calipers require a smaller bore size master cylinder with slightly less volume but more overall pressure. I think thats in the neighborhood of 78 for a manual setup and 1 for power chevynut will correct me if im wrong. Logic would tell you that a larger bore size in a master cylinder should produce more pressure but that is actually not true.
Because of fluid velocity and fluid movement in most cases the smaller the bore of the master cylinder means the more pressure you are going to have at the caliper assembly or the wheel cylinder assembly.
Gallery of Master Cylinder Bore Size Chart
