Difference in Master Cylinder Bore Sizes

The bigger the master cylinder is, the more fluid you get but less pressure at the caliper. The smaller the master cylinder is, the less fluid you get but you’ll have more pressure at the caliper. Think of it like putting your thumb over the end of a water hose. As your thumb decreases the amount coming out of the hose, the more the pressure increases. Most dirt track racers with a dual master cylinder set up choose to run the 7/8" bore master cylinder to the rear and the 1" bore master cylinder to the front. This helps free the car up getting in the corner and allows the car to carry more speed into the corner. Most pavement racers with dual master cylinder set ups choose to run the 1" bore master cylinder to the rear and the 7/8" bore master cylinder to the front. This creates more pressure to the front calipers and helps get the car into the corner straight and flat to minimize tire scrub.