Ford Mustang Drum Brake Performance Improvement
Get better braking with the right technique and parts
It has been proven that four-wheel disc brakes provide superior fade resistance, especially in extreme braking. However, many vintage Mustang drivers prefer the feel of rear drum brakes and the more effective nature of rear drum parking brakes. Of course, there are also owners with concours restored and low-mileage Mustangs who want to keep the stock brakes, which means making the most of drum brakes. Improving drum brake performance means knowing what to do when it is time to do a brake job.
This isn't about rebuilding drum brakes step by step, but rather learning what you need to know in order to make your Mustang's drum brakes perform better. You want good brakes in a panic stop, which means never cutting corners when it's time to do a brake job. When you rebuild drum brakes on the cheap, you're going to get what you pay for.
Shopping for brake shoes can be as challenging as shopping for a camshaft. Mustangs were fitted with bonded brake linings from the factory. Summit Racing offers the choice of bonded, riveted, semi-metallic, and organic, depending on what you want from your brakes.
Drum brake fade is caused by extreme heat during heavy braking when hot shoes gas off and create an air gap between the lining and drum, which is like tires hydroplaning on wet pavement. The gas gap limits lining and drum contact, hindering brake performance. High-performance drum brake shoes have lateral air gaps, which allow hot gasses to escape. They are also made from semi-metallic material, which stands up to heat better than organic. Riveted linings carry heat away better than bonded. They also reduce fade because hot gasses have a place to go.
When choosing between bonded or riveted, the latter offers better performance in hard braking. If you're doing the daily commute or weekend drives, it doesn't matter if you choose riveted or bonded. Semi-metallic linings stand up to heat better than organic. Organic linings are quieter but don't last as long as semi-metallic. In the end, street drivers are happy with either bonded or riveted linings.
Classic Mustangs were fitted with two basic drum brake size diameters—9-inch for sixes and 10-inches for V-8s. After that, it is mostly about shoe/drum width and lining length. The more braking capacity required, the wider the shoe and drum. Mustang drum brake specifications are basically the same from '65-'70, with increases in drum/shoe size for '71-'73.
When you're doing a drum brake rebuild, it's easy to get primary and secondary brake shoes mixed up. The primary shoe always leads toward the front of your Mustang and has less lining than the secondary shoe in back. The secondary shoe with more lining is what modulates the self adjusters when you back up and apply brakes.
Every brake job needs fresh hardware—springs, hold-downs, clips, pins, star wheel adjuster, and cable. Aside from obvious wear and tear issues, brake heat cycling takes a toll on spring tension, which falls off with time and use. Opt for a high-quality Dorman #HW7045 kit from Summit Racing Equipment (V-8 only), which covers front or rear. New parts are suggested because nothing meets factory specifications like new parts.
Any time you do a brake job, cover hydraulics with master cylinder and wheel cylinder rebuilding or replacement. Brake hoses should be replaced at every other brake job or every four to five years. Brake hydraulics should be flushed and bled with fresh fluid every two years when you take care of cooling system maintenance, regardless of how often you drive your Mustang.
|Model Year||Shoe Position||Front Width x Length||Rear Width & Length|
|1965-66 Six-Cylinder||Primary Shoe Secondary Shoe||2.25 x 7.75-inches 2.25 x 10.0-inches||1.50 x 7.75-inches 1.50 x 10.0-inches|
|1965-66 260/289||Primary Shoe Secondary Shoe||2.25 x 8.35-inches 2.25 x 10.75-inches||1.75 x 8.35-inches 1.75 x 10.75-inches|
|1967-70 Six||Primary Shoe Secondary Shoe||2.25 x 7.62-inches 2.25 x 9.77-inches||1.50 x 7.62-inches 1.50 x 9.77-inches|
|1967-70 Small V-8||Primary Shoe Secondary Shoe||2.25 x 8.43-inches 2.25 x 10.82-inches||1.75 x 8.43-inches 1.75 x 10.82-inches|
|1967-68 Big-Block||Primary Shoe Secondary Shoe||2.50 x 8.43-inches 2.50 x 10.82-inches||1.75 x 8.43-inches 1.75 x 10.82-inches|
|1969-70 Big-Block||Primary Shoe Secondary Shoe||2.50 x 8.43-inches 2.50 x 10.82-inches||2.00 x 8.43-inches 2.00 x 10.82-inches|
|1971-73 Six & 302||Primary Shoe Secondary Shoe||2.50 x 8.43-inches 2.50 x 10.82-inches||2.00 x 8.43-inches 2.00 x 10.82-inches|
|1971-73 351/429||Primary Shoe Secondary||Disc Brake||2.00 x 8.43-inches 2.00 x 10.82-inches|