Front disc brakes were perhaps the best value per dollar on the option list when Ford cars were ordered new. Available at a small additional cost, they were a big improvement over the standard drum brakes.
Most of a car's stopping power comes from the front brakes. The factory option only upgraded the front axle, but this was considerably helpful. However, the best setup for modernizing our classic Ford braking system is a disc brake at each wheel. Although a little more expensive, it's worth the money.
Brakes are mechanisms to convert kinetic energy into heat energy. When brake heat is generated faster than it's dissipated, saturation occurs. While an enclosed drum has little way to ventilate heat, the rotor in a disc-brake arrangement is out in the slipstream and is often cast to allow ventilation through the interior of the rotor.
When water is present inside a drum brake, it acts as a lubricant and makes stopping difficult. In addition, often only the drum on one side of the car gets wet--such as when it's driven through a puddle. The result is a nasty pull at the steering wheel when you hit the brake pedal. With disc brakes, water is thrown off the rotor when the pads come in contact with the rotor surface. Disc brakes shed heat and water more readily than drum brakes.
So, the next question is how to install four-wheel disc brakes on an early Mustang or other special-interest Ford. One good answer is a Master Power disc-brake kit for both the front and rear axles. Our '73 Mach 1 Mustang had manual front disc brakes from the factory, but they were in need of a complete rebuild. We want to tackle the whole car at once, adding rear disc brakes while completely refurbishing the front brakes.