Drum Brake Maintenance
Performance doesn't have to be mundane if you remember these simple tips
Jim Smart - January 19, 2012 10:00 AM
Wheel bearings don’t always get the attention they need during a brake job. First, thoroughly clean and inspect bearings, cages and races. Always replace seals. If you’re replacing the drum, replace the bearings. Any roller or race scoring is reason enough for replacement. Bearings and races come in sets. Your best choice is Timken bearings, which are available just about anywhere and manufactured to the highest standards. Use a good, high-temperature wheel bearing grease and let’s keep it all hospital clean in the process.
There’s always an unknown any time you pull drums, so expect to see anything. Finned drums radiate heat better than smoothies and riveted brake shoes get rid of heat better than bonded linings because heat is transferred via the rivets.
This is your typical Ford compact/intermediate self-adjusting drum brake with riveted linings, which isn’t much different than GM and Chrysler drum brakes of the era. You have a wheel cylinder, which applies hydraulic fluid under pressure to the shoes (linings). There is a primary shoe (front) and secondary shoe (rear). The primary shoe has less lining and is what energizes the brake to improve stopping power hence the term “self-energizing” when we speak of drum brakes. The primary shoe, when applied, tends to move (bind) with the drum, which pulls both shoes into the drum. When you back up, shoes pull in the opposite direction, which energizes the self-adjuster, which moves the star wheel adjuster.
Watch for heat damage and cracking. Although brake linings are designed to handle a lot of heat, physics and proper fit remain the rule. Cracking occurs when linings go through extremes of temperature changes. They get hot and you hit a huge puddle, which super cools the linings. Do this enough times and you can crack linings. Cracking here appears to be more due to poor shoe-to-drum contact than anything. This happens from poor drum machining technique, improper shoe installation, or worn backing plates, because linings don’t have uniform contact with the drum.
Save yourself time and frustration. Trot down to your favorite auto parts store and pick up brake installation tools — brake adjustment spoon, and spring removal/installation tools. These tools are cheap, easy to come by, and will serve you well for a lifetime. Wear face and eye protection.
Brake hardware is one of those pesky items we don’t like spending money on. So we keep using worn out hardware brake job after brake job and wonder why braking isn’t as effective as it could be. Every brake job should include new hardware. Springs lose their tension. Retainers wear out. Self-adjuster star wheels and threads must be clean and well lubricated with a thin film of high temperature grease.
Brake backing plates get ignored more than any other braking system element we can think of, yet backing plates are the very foundation of your drum brake system. They wear out. Yet they can be fixed and made like new again. There are also new backing plates and complete drum brake assemblies out there from the aftermarket for classic cars. Ford Racing Performance Parts, as one example, has new drum brake assemblies available for large bearing nine-inch housings. There are good sources for GM brake parts as well.
Worn backing plates can be removed and made like new again. Rub pads where shoes wear into the backing plate can be welded up and machined smooth like new. The main thing to remember is to check shoe alignment with backing plate and drum. Shoes must contact the drum with 100-percent lining contact.
Few of us pay enough attention to axle spindles, but this is all about your safety. Axle spindles must be inspected closely to check for abnormal wear and cracks. Excessive scoring is reason enough to replace the spindle. Check bearing fit before brake assembly. When in doubt, throw it out.
Rear brake overhaul should include axle seals and thorough inspection of axle bearings. Now is the time to replace bearings and seals. Bearings should feel buttery smooth. Any roughness (drag) in rotation is reason enough to replace bearings.
This is a blueprint for great drum brake performance. New Wagner riveted linings parked against a machined backing plate with new hardware. Our experience has shown Wagner brake parts to be the most consistent of any brand out there. You can expect solid, consistent performance from Wagner parts. When you reline, you should rebuild or replace wheel cylinders along with performing a complete brake system flush. Even though you may not drive your collector car that often, flush the brake system every two years and replenish with fresh fluid.
The rule of thumb with brake drums is this: if you can afford it, replace drums at every reline. If not, turn drums once and toss them despite those numbers on the drum. The more you turn them, the greater shoes have to travel for contact. Never turn a new drum, by the way. Drums must be used and heat-cycled over time before they are turned. The same can be said for new disc brake rotors.
The benefit in new drums is shoe-to-drum tolerances. Shoe travel — and corresponding pedal travel — is minimal with new drums. Again, never turn a new drum. If it is irregular, return it to your auto parts store and ask for a replacement.
Braided stainless steel brake hoses from Classic Tube do a better job than stock rubber reinforced hoses. These guys deliver a harder pedal because they flex less than stock hoses. They also outlast stock hoses by a wide margin.
Complete new drum brake assemblies are available from a variety of sources out there. Ford Racing Performance Parts has new drum brake assemblies for large bearing nine-inch housings. Inline Tube offers complete drum brake assemblies and parts for GM cars. There are also good sources out there for Chrysler buffs though we haven’t seen complete drum brake assemblies.
Disc brakes have changed the way we look at braking systems because they vastly improve braking performance and safety. Discs don’t fade under hard braking and they’re virtually unaffected by water.
There’s every reason in the world to fit our classic cars with front disc brakes and dual braking systems, especially if they’re driven regularly. However, what if your collector car was fitted with four-wheel factory drum brakes and disc brakes just aren’t an option — then what?
One good example is this 1961 Plymouth Valiant sedan. Another good example might be your Falcon Futura, Chevy II, or Rambler Classic. These relics of the 1960s were factory fitted with four-wheel manual drum brakes on a single hydraulic system. And like a lot of other rides of the era, they will always have drum brakes because we like them that way. We want to remain true to the old car driving experience, warts and all, because it takes us back to our youth.
Driving a classic car is risky business because safety standards weren’t what they are now. We accept that risk as an integral part of enjoying an old car, which means we not only must drive them more carefully, but also make sure their safety systems are as up to par as possible. So what about that? How do you make drum brakes more effective? For one thing, you can convert your single drum brake hydraulic system to a dual braking system with not much notice, so that you have some braking available, should one part of the system fail. In other words, a dual reservoir master cylinder with front and rear systems separated for improved safety.
There’s no magic pill when it comes to drum brakes. They’re not going to be as effective as disc brakes. However, if you follow these simple suggestions, your drum brakes will be safe and effective for years to come. When it’s time for a drum brake job, replace everything — drums, shoes, hardware, and all hydraulics. Reward a drum brake job with all new parts and start fresh with a good performance baseline you can live with.
Why Go New?
Drum brakes are at their very best with new shoes and drums because it minimizes shoe travel distance and gets the best friction with minimal pedal travel. With all new components, you develop a good feel for how your drum brakes should perform — like they did right off the car carrier.
We cannot emphasize enough the need to regularly maintain your brake hydraulic system with regular flushing and bleeding every two years, just like when you flush your classic car’s cooling system. With either disc or drum brakes, mineral-based brake fluid absorbs moisture through steel lines and reinforced rubber hoses. The more your car sits, the worse this problem becomes. Before you back out of the garage, test your brakes and make sure you have them. Failure is discovered all too often once a vehicle is in motion with predictable consequences.