bigger rear master cylinder?

[dpariso]

I'm not happy with the manual brakes... too much effort to stop all those pony's. I have Wilwood pedals, Willwood master cylinders with Mustang GT calipers. I was thinking about getting a larger rear master cylinder. What are your thoughts about that? Would it help with stopping better?

[NAZ]

The mechanical advantage comes from the pedal ratio (more ratio = more leverage) and the ratio between the M/C and the wheel cylinder (caliper in your case). If the M/C and the wheel cylinders were the same diameter (1:1 ratio) adding a 100lb force to the M/C would create 100lb force at the wheel cylinder. If the M/C was half the size of the wheel cylinder (2:1 ratio) a 100lb force at the M/C would create a 200lb force at the wheel cylinder.

Installing a larger M/C will require more leg force not less. A longer pedal arm or smaller M/C will increase the mechanical advantage. However, there is no free lunch. Increasing the mechanical advantage also increases the distance the pedal (or M/C) must travel.

[2bking]

If you want more stopping power with less pedal effort, the master cylinder size would be reduced. But it's a two edged sword because smaller cylinders mean more pedal stroke so if you get too small, the pedal will hit the floor before developing the pressure needing for stopping. I have the Wilwood brakes and use 11/16 diameter masters which reduces the pedal effort about 15% from the 3/4 diameter masters that came with the kit (2013) with no discernable increase in pedal movement.