Drums Versus Disc Brakes: Should You Upgrade?

Should we upgrade to discs and calipers — or should we stick to the original drums and restore them? This is the question L and I proposed to each other prior to getting our 1965 Clark Cortez motorhome’s braking system operational. Here is our answer . . .

↠ ABOUT THE CORTEZ’S ORIGINAL BRAKE SYSTEM ↞

First, a look at the Clark Cortez — It is truly a mishmash of parts from a wide range of manufacturers so identifying replacements can be tricky, but the Clark engineers wisely chose some of the most commonly used parts in their Cortez design. (Thank you for that!)

The Cortez has four drum brakes from a 1960’s Ford F-250, a master cylinder that is assisted with a Bendix hydrovac unit. It’s not the most advanced or efficient system in the world but it works well.

Fortunately all of the wheel cylinders and shoes are readily available and can be purchased for around twenty bucks a piece. The drums are getting more rare but are still out there.

The brake lines are Cortez specific but easy to replicate and replace if you get carried away with a saw they are damaged. The only tools you would need are a pipe bender, saw, file and flaring tool.

Back in the day a group of Cortez owners set about looking for ways to improve the braking of their RVs. It was discovered that, with a set of custom made mounting brackets, it was possible to mount a disc and caliper set-up on the front wheels. This offered not only an increase in braking performance but also made the system far more simple and service-friendly. No one (as far as I know) ever has gone to the effort of converting the rear drums to disc brakes as there is little to gain in performance or use-ability. Saying that though, here is a look at both . . .

↠ DRUMS VERSUS DISCS AND CALIPERS ↞

Back to the question at hand: Is it worth upgrading from drums to discs and calipers?

The short answer: Yes, but there are pros and cons to the swap.

Here is the long answer . . .

First, let’s talk about heat: Drum brakes are far worse at dissipating heat than discs — Huge chunks of metal with no venting and limited airflow tend to hold onto heat rather stubbornly! Because of limited airflow in and around drum brakes and nowhere to dissipate, heat can quickly build up and easily affect braking. 

Here’s what I mean: When brakes get hot, they ‘fade’ — This is a technical term for ‘stop working.’ The shoe or pad material becomes so hot that the friction between it and the brake drum or disc is reduced . . . because science. This is only temporary though — You either pull over and allow your brakes to cool or you crash into a tree so the same effect is applied.

Disc brakes are far better at dissipating heat than drums. In fact, when brake discs get to a normal operating temperature, they actually perform better — This is because the discs expand and get closer to the pads; therefore, the amount of force applied to the discs increases instead of the pressure simply pushing the piston out further.

In order to get disc and caliper set-ups to suffer from brake fade, you really need to be braking hard over prolonged periods of time. (Of course other factors — such as vehicle weight, disc size, and weather conditions — can contribute to how braking is affected.)

Also, discs now, more often than not, are vented — They have air channels between the braking surfaces so there is a much larger surface area, which allows for more airflow, which then allows for more cooling . . . again because science.

Saying all of this, if you were still set on drum brakes, there are a few methods for improving cooling efficiency, which can really help out.

One option is find a set of drums that match your size(s) that have built-in cooling fins. These fins allow the heat to dissipate more easily through increased surface area and thinner wall sections.

A second option is to get (relatively) cold air to the drums. This can be achieved in two ways . . .

One way: If you want to be all fancy, you can go the race-approved and styled turbo fan design, as used on many race cars of the past. Porsche and BMW where huge fans of . . . fans. In fact, the Porsche 935 (Huge Porsche fanboy, right here) ran the first set of Turbo fans which were manufactured by BBS (Huge BBS fanboy, right here) in the early 1970s. This style wheel is also now extremely popular in the modified car scene for that racecar-look. Hell, even Ken Block uses them! Many people wrongly assume that the design pushes cold air inside the wheel, but the design actually pulls the hot air out from the wheel hub, therefore, drawing cold air in from underneath the vehicle.

How effective these would be on a fifty-five-year-old RV? Who knows!

The second, far simpler and cheaper way is ducting. Taking a cold air feed — a duct from the front of the vehicle — and directing the air onto the back of the brake drums is easier but less efficient. The air is forced to blow over the drums as you drive forward helping them cool.

Second, let’s talk about performance: Disc and caliper set-up will far outperform the traditional drum brake system. This is why you hardly ever see drum brakes on modern cars — and if you do, it is usually only on the rear, which is primarily used for the hand brake/emergency brake on small, cheaper or lightweight vehicles.

Drum brakes are still widely used on larger vehicles such as trucks, lorries/tractors, etc. and this is mainly due to cost, braking efficiencies, and air actuated systems.

Third, let’s talk about serviceability: Drum brakes need a lot more looking after than discs and calipers. As both the shoes and drum wear, the slack needs to be taken up through the adjuster accessed from behind the drum. Although this isn’t a huge undertaking, it is still a job that is eliminated in disc and caliper set-ups. When it comes time for new pads or shoes, changing a set of pads is for easier than changing shoes — There is no intricately set-up spring mechanism ready to fire off in random directions and disappear forever or blind the unsuspecting amateur mechanic. It’s usually just a couple of bolts and maybe some locating pins or shims.

Finally, let’s talk about technology: Brake technology has been constantly developing since the car was born. In fact, the brake caliper was first patented in 1902 (the same year Texaco was founded and a new land speed record of a colossal seventy-four miles per hour was set by Leon Serpollet). It wasn’t until the 1950s that brake discs and calipers became more commonly used and from there, the car industry didn’t look back.

In the end, both systems are simple if you break them down (no pun intended): You press the brake pedal. The fluid in the lines is compressed. The fluid pushes out the brake pistons and the shoes or pads are pushed against the drums or discs. Friction occurs and you slow down. Et viola!

↠ OUR DECISION ↞

So did we do it? No, and here’s why . . .

Honestly, it would have been a considerable undertaking for actually not a massive improvement in capability. Yes, drums aren’t as powerful — They get hot and they need adjusting periodically, but we’re not racing the Cortez. Clipping apexes and hitting braking points isn’t the name of the game. We’re going to amble around in it . . . leisurely. When we encounter a situation where we know the brakes are going to get hot (imagine driving down a mountain road, for example), we can simply use the gears to hold us back and if things get a bit sketchy, we’ll just pull over and let them cool. Simple.

While we could buy the discs, pads, lines and calipers -– from a Ford F250 from the 80s if memory serves me well — there are very few sets of Cortez caliper conversion brackets knocking about, and even fewer that are available to purchase. This would mean we would need to have the brackets made. The cost of having a set made would easily be around $300.

In the end, our choice saved us considerable time, effort, and money but I’m sure the first time the drums overheat and stop working, we’ll rue the day we made that decision. Then we’ll just add it to our list of experiences and learn from it.

If you have any questions or comments on this subject, feel free to leave a message and I’ll be sure to get back to you!