Classic Mustang drum brakes have never been big performers. Even when these cars were new, their drum brakes were problematic, noisy, and often pulled badly. Fade was terrible under hard braking, which is typical of most drum brakes, only it seemed worse on Mustangs.
Fade can happen when brake drums and shoes get extremely hot, causing several unpleasant issues that reduce stopping ability. Any way you look at braking systems, front drum brakes will never be as effective as discs due to the dynamics of each type of brake. Disc brakes tolerate heat better than drum brakes during hard braking. And because front brakes do most of the work when stopping, automakers ultimately switched to power front disc brakes.
When it's time for a drum...
When it's time for a drum brake rebuild, replace everything, including drums, linings, hardware, hydraulics, bearings, and seals. This way, linings mate with drums evenly and squarely for full contact and real stopping effectiveness. When linings aren't square with drums, you get marginal stopping power and performance.
OK, so we agree drum brakes aren't the most effective type of brakes. However, what if you're restoring a Mustang to the window sticker or Marti Report, or perhaps you're doing a six-cylinder hardtop with four-wheel drum brakes and have little choice? How can you get optimum stopping performance from old-fashioned drum brakes?
The best advice we can offer is to pay close attention to detail before getting started. Replace everything-drums, hardware, riveted linings, and hydraulics. Be prepared to sweat the details to ensure your Mustang's drum brakes are in proper working order to deliver the best possible performance.
Because most replacement parts these days are of unknown integrity from origins as vast as the planet, be sure to use genuine Ford Motorcraft parts because no other company has committed more time and money to research and development than the company that designed, engineered, and built your Mustang to begin with. Though Motorcraft parts are usually more expensive, they're worth the difference based on our experiences in nearly 40 years of working with classic Mustangs.
Motorcraft parts are manufactured and tested to the highest standards in the industry. When you do your brakes on the cheap, that's exactly what you're going to get when it's time to test them in a panic stop.
When it comes to parking brake effectiveness, nothing does the job better than a drum brake because they are self-applying by design. As shoes contact the drum, they tend to bind into the drum for better holding power. Disc brakes are not as effective as parking brakes, especially on older Mustangs with T-handle parking brakes.
With the drum removed, you...
With the drum removed, you can see how a drum brake works. A hydraulic actuator (wheel cylinder or brake cylinder) exerts pressure outward enabling the linings to contact the rotating drums to bring your Mustang to a stop. There are two shoes-primary (front) and secondary (back). The primary shoe has less lining than the secondary. Drum brakes lose performance through wear and tear. Linings glaze from wear and drums get a mirror finish from wear. Backing plates wear at shoe contact points, causing uneven drum contact. Wheel cylinders develop leaks, which reduces hydraulic pressure and contaminates linings. All of these elements adversely affect braking effectiveness.
Look what extreme heat does...
Look what extreme heat does to brake linings. It not only causes glazing, but also cracking from thermal expansion. Cracking also comes from uneven drum contact, which stresses the shoe and lining. By the way, the best shoe to use has a riveted lining because rivets help carry heat away in hard braking.
One of the biggest culprits...
One of the biggest culprits in poor brake performance is self-adjusters that don't work correctly. Star wheel adjusters should have clean threads with a thin film of high temperature grease. Teeth should be well defined so the adjusting lever engages and moves the star wheel when you back up and brake. The star wheel should turn in a direction where shoes move outward toward drum.
The secret to Mustangs Etc.'s...
The secret to Mustangs Etc.'s success with drum brakes is a rebuild, not an overhaul. Drum brake assemblies are completely removed from the car and rebuilt with new components. Line disconnection is performed with a tubing wrench. Fittings should be bathed in WD40 penetrating lubricant before attempting removal.
This is the wheel cylinder,...
This is the wheel cylinder, which moves the brake shoes outward for drum contact. Retraction springs return the shoes to rest when brake application ends. Wheel cylinders should be replaced or rebuilt at every brake job along with brake system flushing and bleeding.
Backing plates wear at the...
Backing plates wear at the shoe rub pads, which causes the shoes to distort. You have two choices here. Have a machine shop weld up the rub pads and grind them back to proper specifications or replace the backing plate. Mustangs Etc. does an off-vehicle rebuild on all drum brake jobs, restoring backing plates to original condition as shown.