Report Brake master cylinder info in Ride/Handling/Suspension/Brakes/Wheels/Tyres Posted March 20, 2015 Great post dixi4uk. I didn't think brake fluid capacity at all. Actually I know how to calculate master cylinder size but just wanted to know what is the stock diameter for Evora master cylinder to get into right ball park. It probably reads in casting. My current is 7/8 and there is also 15/16 available for my car. In brake sizing you would normally start from finding out Center of Gravity and calculate weight transfer in braking. Then you would know how much braking force you need in each wheel. But lets not get into that because I can't use dual master cylinders. For hydraulic leverage ratio you'll need to calculate piston areas. Evora front calipers have 39mm and 35mm pistons. You need only calculate area from one side because opposing force is the same. Combined that's 2156mm^2 and master diameter is 22.22mm = 388mm^2. If you divide caliper area with master area you'll get ratio of 5.56. My stock brakes have single 51.5mm piston and area of 2083mm^2 and that would be ratio of 5.37 so there isn't big difference. Of course there is pedal leverage and brake booster in top of this. If someone can check diameter from Evora master cylinder I would still appreciate it.