Why do I always see people saying drum brakes are simpler than discs?


#1

I was doing the rear shoes/cylinders on my old truck last night and it got me to wondering about that. Disc brakes are a piece of cake. Loosen 1 bolt, remove a second, flip up the caliper, swap pads, re-bolt. Done.

Drum brakes have 500 little fiddly parts and springs in them and take me much longer than discs. So, what’s so simple about them?


#2

Disc brakes won our over drums because they are more fade resistance. Having said that, heavy trucks still have mostly drum brakes; there is more room for them on trucks.


#3

I agree @shadowfax - discs are much simpler to work on. Please let’s not restart the ‘which is better’ discussion…


#4

Wasn’t looking to get into which was better. That answer is obvious. Anyone with doubts should look at a race car, which needs to have out-of-this-world braking performance. What kind of brake does it have? There’s your answer.

But which is simpler, is confusing. Every time I see a post or an article extolling the virtues of drums, “they’re simpler” is almost always prominently mentioned, and I don’t understand what is simpler about them. Any other system you can think of, more parts = more complex. My truck has one of the simpler drum brake designs and it still has 5 springs per drum, 2 of which are a royal pain to put on. How is that possibly simpler than a disc from any perspective?


#5

Drum brakes aren’t simple at all. It is just an older technology. As the OP said lots of little parts, springs etc. On rear brakes you have extra hardware for the parking brake. The self adjusters tend to freeze up with rust.

What drum brakes have is lots of braking power, and they can be compact compared to a disk brake. To get strong braking power out of a disk you need bigger wheels to allow for bigger disks. In the '60’s big cars often came with 14" wheels. I’m talking Caddy’s and Lincoln’s.

The problem with drum brakes is they don’t dissipate heat as well as disks. The reason is obvious as the brake parts are enclosed inside the drum and don’t get much airflow to cool everything off. The disks and calipers are just hanging out and get lots of cooling airflow. After one hard stop the drum brakes will be hot so the 2nd hard stop will take a lot more distance, and the 3rd even more. Racing involves a lot of hard, frequent braking and that is where disk brakes proved their worth.

Big trucks still use drum brakes due to wheel size restrictions. They use air brakes to increase the power but on long hills the brakes can overheat. That’s why you see those truck run off emergency ramps on long down grades.

Another issue with drum brakes is when they get wet they just don’t work at all until you heat them up to get the moisture out of them. Disk brakes recover from a good wetting much faster.


#6

The “drum brakes are simpler” and the “drum brakes cost less than disk brake” speakers are the same folks. Old brake engineers and mechanics that just won’t admit drum brakes are not the better design.

Disk brakes are so obviously simpler if you just the parts count and drum brakes only cost less if you include the parking brake in the design. Front drums and front disk brakes cost basically the the same to manufacture, give or take a bit. Because of the parking brake issue and the fact that most rear brakes do 1/3 or less of the braking, drums are still used on many vehicles.


#7

@shadowfax, have you ever replaced the pads and rotors on rear disc brakes that do not use a mini-drum? They can get a bit complicated.


#8

I remember the last rear drums I worked on being a total pain. Even broke my spring tool trying to do it. I can’t remember what car it was anymore but one of those front pads, rear drum models GM used to like to do. Now on my list of deal breakers, 4 wheel discs is a must. Now you can’t even adjust them anymore because that little window isn’t there anymore and you have to use a measuring tool before you put the hub back on. I still have the broken tool in my tool chest wondering if I should weld it up or not, but no, I don’t intend to ever do drum brakes again.


#9

And yet . . in my 40 years as a parts man . . I’ve never sold so many REAR brakes , till the rear disc brake came along !


#10

Any person who says or believes that drum brakes are easier than disc brakes has never worked on either one.


#11

“Any person who says or believes that drum brakes are easier than disc brakes has never worked on either one.”

I’ve worked on both. I won’t say a rear drum is easier to work on than a rear disc without the mini-drum, but it is a tossup on at least some vehicles. Building the parking brake into the rear disc presents some challenges.


#12
Disk brakes are so obviously simpler if you just the parts count and drum brakes only cost less if you include the parking brake in the design.

That’s it right there. Drum brakes aren’t simpler than discs…they’re simpler than the “disk brake, plus drum parking brake” assemblies that DOT regs require. (OK, they don’t require them…they require a parking brake, fully separate from the hydraulic system for the regular brakes, that favors such a setup.)

I’m quite the “retro grouch” about a lot of things…but IMO, disc brakes are pretty much an unmitigated improvement over drums.


#13

The big advantage I see in disc brakes over drums is water. Get drum brakes wet in a deep puddle and the water just stays in the. We used to have to “ride the brakes” to get them to dry out. Disc brakes spin dry.

Other than that, it’s strictly preference.


#14

Yeah, I’ve done rear disc/parking drums. I don’t consider that to count toward the disc vs drum simplicity argument because… Well, because there’s a drum brake in there! Adding the more complicated thing to the less complicated thing does not make the more complicated thing less complicated! :wink:

That said, unless you screw up and let the rear disc pads go down to the backer plate, you probably won’t have to replace that rear disc/drum combo before you get rid of the car. It sees pretty light duty compared to the front.

I’m glad to see the consensus is that drum brakes are not simpler, because I was seriously starting to wonder if there was some giant gap in my brake knowledge.


#15

@shadowfax, You misunderstood me, there are rear discs that do not use the mini drum brake, the parking brake function is built into the caliper. Some of those are not too hard as it only involves turning an Allen bolt so many turns to reset the parking function, but there are some (mid 90’s GM) that will give the drum brake a run for the money on difficulty. Other than those, I do agree with you.


#16

Not all drum brakes are equally complicated with an assortment of springs and levers. In regard to a number of older foreign cars the rear drums are bone simple.
The older Subaru drum brakes for example have 2 shoes, 2 springs, and 2 pins to hold them on. With the drum removed it’s a 30 second job to swap shoes.

Those Subarus also used the front disc brakes as the park brake much like the older SAABs.


#17

I am convinced now…and always…that Bendix during the war efforts manufactured 17 Bazillion sets of drum brakes and ancillary parts n pieces and the auto industry has been looking for ways to foist them upon us. How else can one explain the present day prevalence of these antiquated stoppers?

That’s my story…and I’m stickin to it… Haha

Blackbird


#18

I concur w/you @shadowfax , in my experience, disc brakes are much easier to service than drums.


#19

The rear disc design with a built in drum is a real salt magnet. On my 2012 Camry I had to replace the rear pads because the drivers side was completely rusted up in 2 years and 18000 miles, same thing again in 3 1/2 years and 28000 miles. And yes, I had wire brushed and ground all the rust off the calipers and slides and greased everything.
My son had the same problem with his 2007 Sonata at even earlier miles until he oved to Florida 4 years ago, He has not had to touch his brakes since.

Thissummer I am planning on replacing the rear calipers, does anyone have an opinion on NAPA calipers?


#20

Ever since I did my first disc brake job, I’ve hated drum brakes.

Trying to back off the brake shoes to remove the drum, frozen spring keepers, frozen adjusters, all the moving parts. Then trying to get those danged pins and keepers locked (I always struggle with them) and then adjusting the shoes to the drum.

Way harder that the simplicity of disc brakes.

I find the hardest part of disc brakes is getting the old disc’s off the hub.
Not that I have that much trouble…I’ve learned a few tricks through the years.
But I find that part, the only thing that causes me to any angst.

Actually that is #2. Number one…here in the rust belt is removing the flare nut from the flexible brake hoses. The nut us normally rusted to the steel line into one piece and unless you are careful you will twist the steel line right off, and there is never enough line to reflare it. Heat, some PB blaster, and working the nut back and forth is the only way…if you are lucky.

But that holds true if it’s a disc brake set up or drums.

Yosemite