Technically, the original Bendix disk brake system is of a superior design, to the Turner and Steel-Tech systems. It has a massive, rigid caliper bridge, fixed to the spindle and straddles the rotor and allows a piston to apply brake pressure to each side. Each piston rides on a steel pin, fixed in the caliper housing. The base of the piston has the guide, which is a small spring that binds on the pin. The spring extends slightly when you apply the brakes and retracts the pad, the same amount, when the pressure is released. This action of pulling the pad away from the rotor, contributes to less pad wear, less rolling resistance and cooler rotors, as well as a self-adjuster mechanism. Another feature is, that the pads/pistons will only extend a fixed amount, preventing a pad from wearing down to the steel. A worn pad can never contact and gall the rotor. When the limit is reached, the braking effect diminishes. So, if the original Avanti disk brakes start to pull, they may be telling you to change the pads.
The very same brake system was being used on Ferrari, Aston-Martin and Jaguar, of the period. They are still manufactured, today, in stainless steel, to the exact same specifications. The company is named Hye-dra-cyl, in St. Charles, MO.

Bendix disk brake technology was, naturally, developed on the race track and used metallic pads, which have a some traits that many don't like. Metallic pads have to be ‘warmed’ up a bit to function properly. They do work, from a cold start, but you might experience a lack of expected effectiveness, until you apply them a couple times. Organic pads have the same, general degree of effectiveness from cold to warm, but have a performance limit, called heat fade. When organic disk brake pads were first used in passenger cars, the pad composition would tend to trap the heat, generated from hard braking, at the rotor. The high temperatures would glaze the pads and with the solid rotor, making the Bendix system and others like it, prone to heat fade. Using metallic brake pads will wick the heat away from the rotor and to a large degree, prevent this ‘heat’ fade. Brakes with metallic pads will never drop below 80% effectiveness, not matter hot they get and these were the OEM pad on the 1963 Avanti. Developmental testing showed the Bendix brakes maintained a superior braking action, even though the temperatures exceeded 1000 degrees.

Solid disk rotors, used on race cars today, are drilled, slotted or grooved to help alleviate high temperatures and most always use metallic or now, more exotic pads. The, original, Bendix rotors were cast of “gray iron” and can withstand a lot of abuse. On occasion, they can get scored, but with general use and decent maintenance, will remain usable for quite a while. Replacing the pads is a simple exercise that takes around an hour, at most. The original rotors on my car had 140K miles on them, when removed, and had no scarring nor were they ever turned.

Most all, modern passenger car, disk brake systems, use a floating caliper and a vented rotor, made of a softer alloy. Vented rotors were developed to counter brake fade and generally, always, use organic pads. The rotation of the vented disk, will draw cool air into an opening, near the spindle, and force it out the vents between the disk sides. The airflow will also draw in moisture and will eventually rust the vents closed, contributing to their demise. These “floating” systems can only rely on the small amount of rotor wobble or wheel bearing run out to move the pads away, when the brakes are released. Some modern calipers, now, have a piston seal, that twists on application and when released, return to normal profile, providing some pad return. Basically, the floating caliper systems of the 70’s and 80’s were cheaper to manufacture and are more quickly installed in the factory. They have no requirements for shims to adjust clearances, etc. They have fewer parts and are effective, but a properly maintained Bendix disk brake system works fine and will easily, match the braking effectiveness of these aftermarket systems.

(*) 1) It is very important, that when rebuilding the Bendix calipers, you remove the piston, with air pressure, applied to the fluid line recess. Prying the piston out of the cylinder will inevitably, bend the guide pin and render it useless.
2) On reassembly, be sure to adjust your wheel bearings before shimming the calipers.