By Ron Ceridono
By their nature hot rodders always strive to improve the performance of their cars, and those improvements come in many forms. Increasing acceleration has always been a priority, but coming to a safe stop is just as critical, in fact sometimes more so. Being outrun by another hot rod is one thing, not being able to stop in time and running into an immovable object is much worse.
History of Drum Brakes
Who invented drum brakes? The answer to that is multifaceted. Gottlieb Daimler is usually credited with developing drum brakes in 1899, which used a cable as a friction device. However, it was French manufacturer Louis Renault who obtained a patent on a drum brake that used a woven asbestos lining. In both cases these brakes were the external contracting type—the friction material was wrapped around on the outside of the drum and was tightened to provide stopping power.
Given Henry Ford’s mechanical intellect it’s surprising that his first car, the Quadracycle built in 1896, didn’t have brakes of any sort (it did have a doorbell to warn people he was coming). However, by the time he produced the first Model A in 1928, he equipped his cars with four-wheel mechanically operated drum brakes. These were the internal expanding type with the brake shoes inside the drums.
Types of Drum Brakes for Hot Rods
What are Ford Juice Brakes
As Henry Ford felt mechanically operated brakes were simple, and they were inexpensive, he refused to use hydraulic brakes until 1939, long after other manufacturers had made the change. Often referred to as juice brakes due to the fluid used, hydraulic brake systems can create significantly more force to press the brake shoes against the rotating drums than a mechanical system—the result is greater stopping power with less pedal effort.
Over the years, a number of brake swaps have been used on early Fords. One of the most popular types of drum brakes was the 1939 to 1948 Lincoln drum brakes. While both the Ford and Lincoln had 12-inch drums, the more efficient Bendix design used by Lincoln improved stopping considerably compared to the Ford Lockheed-style brakes. In the hot rod world, the Bendix Lincoln drums are considered the first performance drum brakes.
Thanks to the more sophisticated design, Bendix self-energizing brakes increase stopping power dramatically compared to the Lockheed style.
Simplex vs. Duo Servo Drum Brakes Explained
How do drum brakes work? There are two common types of drum brakes. Ford Lockheed brakes use a pair of brake shoes each anchored at the bottom the backing plate. As a result, the shoes operate independently of each other. This is referred to as simplex drum brake operation. Alternatively, Bendix drum brakes use shoes that are hooked together at the bottom by a spring and adjuster and are held to the backing plates by pins, springs, and retainers. Mounted this way, they are free to move slightly on the backing plate. This is referred to as duo servo drum brakes, also known as self-energizing brakes. When self-energizing brakes are applied the front brake shoe makes contact with the revolving drum and tries to rotate with it. That movement is transferred through the adjuster to the rear shoe, pushing it into the drum with increased force, making them more effective than the Lockheed design. This creates a wedging action, increasing brake force and improving pedal feel versus simple drum brakes.
Buick Finned Drum Brakes
Arguably the pinnacle of drum brake design was found on the 1958 to 1970 Buicks. These cars used 12-inch finned aluminum drums with iron liners (1958-1965 drums had 45 fins 1 inch apart, later drums had 90 fins ½ inch apart). The advantage to finned drum brakes is the finned aluminum outer surface dissipates heat much more effectively than a standard cast-iron drum, which helps prevent brake fade. Hot rodders discovered that Buick’s performance drum brakes could be adapted to their Ford backing plates, making them the best drum brakes available for hot rods.
Which Is Better, Drum Brakes or Disc?
Are Drum Brakes Bad?
In terms of effectiveness drum brakes can generate as much stopping power as disc brakes; they just can’t do it when repeated high-speed brake applications are involved. All brakes rely on friction between two surfaces to stop the car and when those surfaces get hot the coefficient of friction between them is reduced and the brakes lose effectiveness. The term for this is brake fade, which is the primary consideration when comparing disc vs. drum brakes. In this regard disc brakes have an advantage over drums as a large portion of the discs are exposed to air, which helps them cool. By comparison with drum brakes most of the friction surface is in contact with the brake drums, which leaves little surface area for cooling; as a result drum brakes get hotter faster and stay hot longer.
Do Drum Brakes Last Longer?
When it comes to maintenance, changing drum brake shoes is only slightly more complicated than swapping disc brake pads due to springs involved. If you have a diagram (included in most drum brake rebuild kits), drum brakes are not hard to change. However, due to the much larger friction surface of drum brake shoes they will outlast disc brake pads by a considerable margin, so there is less maintenance involved.
Why Are Drum Brakes Still Used?
Are drum brakes safe? Drum brakes are safe and effective; one of the reasons is they are common on heavy-duty trucks. When used on a relatively lightweight, traditional hot rod, performance drum brakes will generate more than adequate stopping power reliably. From a visual standpoint drum brakes look era-correct when disc brakes would look out of place. In summary, the advantages of drum brakes extend beyond friction surface area; they have aesthetic appeal as well.
How To Improve Drum Brake Performance
There are a number of methods to improve the performance of early Ford brakes. The most effective is to upgrade to Lincoln-style Bendix brakes. Speedway Motors offers a variety of juice brake kits for that purpose (check Speedway Motors for a complete listing).
For increased cooling and added hot rod flair, Speedway Motors offers drum brake cooling scoops for Lincoln backing plates and others with minor modifications, PN 9106103. These brake cooling scoops fasten to juice brakes with small screws.
