Why are there different size master cylinder bores?
The bigger the master cylinder is, the more fluid you get, but you’ll have 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. On most dirt cars with a dual master cylinder set up, most racers 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 you’re able to carry more speed into the corner. On most pavement cars with a dual master cylinder set ups, most racers 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.
