Thread: Booster ?

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One problem with underfloor pedals like I have is the actuation ratio may only be 4:1, which won't work without a booster. You need something in the 6-7:1 range for manual brakes. Then you get lots of pedal travel. What size of booster you need can vary with the calper and rotor combination. I have Wilwood 6 piston front and 4 piston rear with 12 inch rotors. I wouldn't bother with any single diaphragm booster. I ended up with an 8 inch dual. The second diaphragm only adds about 25% more force. With Willwoods, no rear pressure reduction is needed. A change from a 1 inch MC to a 7/8 inch made the brakes a little too sensitive and made for more pedal travel than I liked.