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New Member
Mar 1, 2020
What size brake master cylinder is everyone running that are using the factory f550 brake calipers? Thanks
Use the factory F550 master.
Because those brakes are massive and you're not stopping a car with these and a manual pedal (I'm assuming that's what you want to do).
There are two things that will get you when you change your brake calipers, the mechanical lever ratio for the pedal to the MC and the hydraulic ratio from the MC to the calipers. Using the factory matching MC will take care of the hydraulic ratio (so you don't push too little, or too much fluid) then you need to take into account if the mechanical lever has enough throw at the right leverage to move the piston in the MC enough. That is where you will have some trial and error.

At least you have something to go from, when I did mine with special Wilwood calipers they did not match anything "stock" so I had to do all the math, then select an MC that worked, then adjust the mechanicals to get a pedal that felt good and provided enough leverage to stop the vehicle.

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