The longer the pedal ratio, the farther you'll have to push the pedal (8:1 is long and 4:1 is short). It's common for rods to have 5:1 or 6:1 pedal ratios for manual brakes. For power systems (depending on booster diameter), a 5:1 ratio will work fine. Example: A brake pedal footpad 10 inches from the pivot with a mast0r cylinder arm 2 inches long (from the pivot) would give a 5:1 ratio. Check the photo on the pedal ratio formula.


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At the master cylinder, a smaller bore diameter will increase pressure and move slightly less fluid per stroke, while a larger bore diameter will move more fluid and give slightly less pressure per stroke. Slightly means changing diameters 1/16 inch at a time. The conclusion from #1: If the pedal in your rod feels hard and the car doesn't stop very well, you can decrease the master cylinder bore diameter. A smaller bore diameter will increase pressure to the calipers and wheel cylinders, and offer a slightly higher pedal. Change the bore diameter 1/16 inch at a time, or absolutely not more than 1/8-inch-diameter smaller bore. To achieve more force at the front calipers or rear wheel cylinders, without changing any other components, increase their bore diameters. More piston area at the wheels equals more pressure. An under-boosted 1 inch and larger bore diameter master cylinder can give a stiffer-feeling pedal. However, it will deliver less pressure than a 15/16 or 1-inch bore, but push more fluid. Using a 1-inch diameter bore as our center line, master cylinders with bigger than a 1-inch bore give less pedal travel, yet give a firmer feeling. A smaller diameter bore (15/16 or 7/8-inch diameter) will yield more pedal travel and give a soher feeling, but provide more pressure than a 1-inch bore.


Like a "cheater bar" on a short wrench (to get more leverage), a larger diameter tire acts as a (longer) lever, and more braking is needed than with a smaller diameter tire. The big and little tire sizes on a rod will also bring the weight more to the front of the car. The biggest single pressure improvement you could make on your rod to make it stop better than ever is to use a larger diameter booster. If we could all have enough room to use 10- to 12-inch-diameter boosters, this story would probably have another twist.