Old Ford drum brake history and tutorial
Pre 1967 old Ford cars and old Ford trucks used a drum brake system. In these systems, pressure applied to the brake pedal is transmitted to the master cylinder, which in turn disperses the energy ultimately to the brakes in each wheel. The master cylinder uses the brake fluid to move the wheel cylinders, which in turn moves the brake shoes in the drum.
There is a front and back brake shoe, the rear one for stopping a vehicle in drive and the forward one for stopping a vehicle in reverse. When either shoe is pressed against the anchor pin, the brakes are engaged, and the vehicle comes to a stop. The brake pads form the shoes to the anchor pin so there is no slipping. The padding on the rear brake shoe is typically longer and sometimes made of a different material to allow the shoes to wear at a similar rate, since the rear shoe sees much more use.
The brake shoes are secured in the drum with both hardware and return springs, which must meet ideal sizing and tension specifications for your make and model for top brake performance. These parts should be replaced any time you work on the brakes in order to counteract wear and tear that can lead to longer stopping times.
Stock brake line hoses will have a rubber lining, while aftermarket hoses are available in a stainless braided wrap to preserve the hose. Whichever type you get, make sure the hoses are the correct thread size and length for your year and model and meet DOT safety standards. The rear wheel drum brakes will also contain the parking brake mechanism and will have a cable to the parking brake.
Brake pipe must be double flared and use flared nuts. It can be purchased with the flaring already completed or you can cut your own and flare it yourself, but it should meet or exceed DOT safety standards.
Hydraulic brakes will fail if there is a weak point in the system, so make sure all your hose and fittings are SAE rated and correctly installed. If you are unsure after installation, test the brakes at low speed in a safe area, such as your driveway or an empty parking lot before taking the vehicle on the road.
Starting in 1967 all old fords have a dual master cylinder. This part separates the wheel hydraulics of the front and rear of the car, so a failure in one will not cause a failure in the other. In vehicles without this feature, a leak anywhere in the brake line will cause the entire brake system to fail. With a dual master cylinder, a leak in the front brake system will not affect the rear and vice versa. This is standard in vehicles made after '67, but it's a good safety upgrade for older classic Fords as well.
Many classic Ford owners choose to upgrade their front brake system to disc brakes, or the complete system. Drum brakes can overheat and fail in high braking conditions, such as rapid stops at high speeds or driving downhill on mountainous roads. Disc brakes are open and exposed to the outside air, which prevents overheating and brake failure. While this upgrade is not strictly necessary, it's a good idea if you frequently drive in hilly or mountainous areas.
Original Ford brake shoes used asbestos in the brake pads. If you are working on a vehicle with its original brake shoes or if you are uncertain if they are original, wear a respirator rated for asbestos while working and wet the brake pads before opening the drum to prevent the asbestos from becoming air born. When cleaning dust from drum brakes, use a dense filtration system to trap the asbestos and dispose of it properly.
You can resurface a drum with minor surface issues, but make sure it stays within factory limits for your year and model. Worn or thin drums can break apart or crack and cause brake failure. If you see excessive wear and tear, replace the drum.
If you are replacing a leaking wheel cylinder, it's a good idea to do them all at once, including the master cylinder. If you have had problems with one, you will soon have problems with the rest. In addition, you won't need to remember which cylinder was replaced when for future maintenance if they were all replaced at once.
You can use a vacuum bleeder to remove old brake fluid and contaminants. Once you remove the old fluid you can use denatured alcohol followed by air to purge the lines. Vacuum each cylinder, including the master cylinder, and replace the old fluid with new, DOT 3 or 4 fluids. When changing fluid, change the rubber hoses and seals. If you have a combination disc and drum system, only use DOT 4 fluid. To ensure a complete cleaning, vacuum some of the new fluid through as well do catch any missed contaminants.
When working on or near the brake line, make sure no petroleum-based liquid, such as gasoline, oil, or mineral oil, encounters the hosing. These oils can break down the rubber and cause hoses to start leaking. Make sure to wash your hands thoroughly before and during working on the brakes system to prevent this, especially if you have been working on other parts of the vehicle.
When working on your brakes, make sure to follow safety precautions, use safety rated parts, and check over your work carefully. Drum brakes are a very important part of the machinery, and due to the hydraulic system, can easily lose stopping power or fail if something is wrong, especially without a dual master cylinder. Whether you're doing regular maintenance or upgrading the whole system, working carefully will ensure a successful job for your vehicle.
