The Underappreciated Drum Brake

General Discussion
41

“Manufacturers went to discs BECAUSE IT WAS CHEAPER FOR THEM !”

Actually drums are much cheaper. Why do you suppose the cheap econoboxes were amoung the last cars to finally convert over for 4 wheel disc setups? Up until a year or so ago on the most basic trim levels on some VW’s you get drum brakes in the rear whilst higher trim levels get 4 wheel discs. After taking a shellacking from the press and car enthusiasts about the embarrassingly cheapened and de-contented North American market Jetta, VW was forced to reinstate disc brakes (and some other things) for the 2012 model year.

42

My rear drums lasted 225k miles. So they can last. That’s on a 95 corolla.

43

If drum brakes are so much better, why do raceing cars use disk brakes? Jay Leno, as you know, can afford to do anything he wants to his cars. When he modernized his Roadmaster daily driver, Jay put Corvette disk brakes on all 4 corners.

44

@Bing Some backing plates don’t have the adjuster hole punched through. It’s premarked and you just have to punch it through and install those rubber dust plugs.

45

Well I was up last night thinking about disc vs drums and I called my buddy who has an old dodge power wagon and set up a test drive this morning, It has 4 wheel non power drum brakes. I took it out to the county road, with a batttery being chared by a generator instead of alternator, the carbureted motor was a bit fussy but once it warmed up watch out,

Well anyway I takes it on the county road and got up to about 50 and made a panic stop, and it pulled a bit to the right but stopped before i hit my imaginary mark, I repeated this test again and the second time and went maybe 55. Well it started well and all but once i got to about 40mph we started to get some brake fade, i then did the test again and from 55 to 50 it was stopping good but then I experienced total brake fade, and barely got the rig stopped in time before the t intersection which is always empty.

So yes drums don’t stop as well as I remember, at least on a power wagon. Someday I will get my camaro going again and will be able to test it but its been sitting since the accident.

So its possible my good friend the drum brake is a fair weather friend,

46

Moderator, if your’re reading this . . .

Now would be a good time to close this thread.

47

@Triedaq Rick should be forced to drive and maintain a 1950 Volkswagen Beetle with mechanical brakes for a one year period. Non-hydrualic brakes, even “self-adjusting ones” were tricky and a panic stop would easily send you off course. The cable parts were not really self-adjusting. Our family once had a 1929 Chevrolet with mechanical brakes; it was a nightmare.

@WheresRick Your posts have been highly entertaining so far, but this site is mostly populated by highly experienced car buffs, ranging from engineers to DIYers to mechanics, who have a keen interest in communicating HOW THE REAL WORLD WORKS!!!

During WW II our family (in Europe at that time) used horse and buggy; very “romantic” but slow and cumbersome. Later I maintained both familiy cars as a teenager and those oil changes and grease jobs every 1000 miles were a chore. Replacing plugs and points every 10,000 miles was tedious as well. In spite of all this care, our 1941 Chevy needed a ring and valve job at 90,000 miles. And it had an “optional” oil filter. Oils and engines have improved immensely since!

As a maintenance consultant, I believe the best mainteance is maintenance you don’t have to do. Our son has a 2004 Mazda3 stickshift. At 125,000 miles now he has only had to do the brakes as an actual repair! He has changed the coolant and a couple of hoses, had new plugs installed and that’s about it. All other stuff, except the wiper blades are original, even the battery. The car is totally reliable. and he recently made a 4000 mile holiday trip with it throughout Western Canada and the Western USA. It has disc brakes, and all that other modern stuff you find so unreliable.

By comparison, at 100,000 miles my 1988 V8 Caprice and 1984 Impala, some of the best US cars of their time, had 13 and 15 items replaced under “repairs”. The Caprice needed shocks, 2 batteries, 2 brake jobs, alternator, exhaust system, starter, U joints, fan motor, rear axle seals, intake manifold gasket, positraction fix, and starter. All parts were “genuine” US made.

The Impala needed 2 sets of shocks, 2 brake jobs, ball joints, 2 batteries, 2 exhaust systems, starter, fan motor, water pump, heater core, radiator, front springs. All “genuine” US parts.

These were your best cars of the era and used by the FBI, as taxis everywhere, most government staffs, etc. JUst watch any old movie or TV program. Many parts were the same as your truck.

In the 60s and 70s there was a “back to the earth” movement for those who longed for a simpler life. These communes produced some of the most incompetent “farmers” I have ever seen. Having been raised on a farm that made money, I shook my head at the idiotic practices carried out. These people have grown up now and hold down government or industry jobs but still support organuzations, like Greenpeace, that promote this impractical lifestyle.

48

@db4690 Moderator I dont agree with things rick are saying so please put an end to this debate.

Anywho… All I was trying to say is that our good old drum brakes did a remarkable job for years and are still used where maximum friction surfaces are required such as semi trucks, heavy equipment ect…

I owe the fact that my camaro accident wasnt worse due to drum brakes, I was going down a hill and lost my brakes to no fault of the drums, I had a hydraulic failure, and had to use the parking brake to stop. Thanks to the self energizing drum brakes I was able to slow down enough when I had to ride the guardrail to slow down I had scrubbed off enough speed I had minimized the damage.

49

“…maximum friction surfaces are required such as semi trucks, heavy equipment ect…”

Ah, no didn’t read my post did you, semi-truck are going to disc brake so they have shorter stopping distances. The surface area is just a function of how big the pad is, nothing more. Semi-trucks didn’t go to disc because of the problems I noted.

50
My rear drums lasted 225k miles. So they can last. That's on a 95 corolla.

That’s NOT necessarily because they were drum brakes…but because they were REAR brakes. The front brakes do 80% of the breaking.

But drum brakes are a LOT harder to change. I can change the pads on my 4runner in 5 MINUTES per side…The fastest time I EVER did a drum brake was probably 30 minutes.

51

@rwee2000 I did read your post, however I am friends with several truck drivers and no one has been assigned to a rig with disc brakes. What large company has disc brakes on thier rigs?

52

I suppose there is a good reason disc brakes are used on heavy aircraft,even the ABS systems were basically developed for aircraft-Kevin

53

@WheresRick

I wanted the moderator to end the debate because you’ve apparently finally recognized that cars with drums at all 4 corners aren’t the way to go anymore.

While I don’t agree with your opinions, that’s not the reason I wanted this discussion to end.

Everything had been said.

That’s why this discussion should be closed.

54

@db4690 Well I don’t think the horse is dead yet, we need to beat it a bit more.

55

Drum brakes were OK when everybody had them, now with better disc brakes those with drums and driving aggressively would end up rear ending a disk brake car stopping shorter than possible for the drum brake car. Just because they worked OK then doesn’t mean they would now.

56

Rose colored glasses are hard to remove, aren’t they?

57

Yeah, I like tube radios, carburators, incandescent lamps, dial phones, tires with tubes and heating with wood.

58

those inner tubes held several bottle of moonshine from what I hear.

Imagine if they tried prohibition today…

59

The drawbacks of drums are

They over heat easier, are harder to service, harder to inspect and just do not stop a car as well.

The drawbacks are with discs are:

  1. When using metal-based pads (common these days), disc rotors tend to warp far more often, especially on the front. They will tend to squeal more unless anti-squeal shims are fitted to the back of the pads.

  2. Drum brakes warm up faster in very cold weather.

  3. Loose gravel stones wedged between the rotor and calipers will cause damage.

  4. When driving through wheel-deep water, disc brakes (especially with metal-based pads) do not work as well as drums until the rotors spin the water off.

  5. When used as a parking brake, rear drums tend to work better.

  6. Disc brakes rely on pliability of caliper seals and slight runout to release pads, leading to drag, fuel mileage loss, and disc scoring. Drum brake return springs give more positive action and, adjusted correctly, often have less drag when released

From Wikipedia-

Due to the fact that a drum brakes friction contact area is at the circumference of the brake, a drum brake can provide more braking force than an equal diameter disc brake. The increased friction contact area of drum brake shoes on the drum allows drum brake shoes to last longer than disc brake pads used in a brake system of similar dimensions and braking force. Drum brakes retain heat and are more complex than disc brakes but are often the more economical and powerful brake type to use in rear brake applications due to the low heat generation of rear brakes, a drum brake self-applying nature, large friction surface contact area, and long life wear characteristics

Again lets show a little respect to our old friend the drum.

60

1) When using metal-based pads (common these days), disc rotors tend to warp far more often, especially on the front. They will tend to squeal more unless anti-squeal shims are fitted to the back of the pads.

You can get a variety of pad compounds for virtually any car some are softer and others a are harder. If you buy high quality rotors (Brembo,EBC, Wilwood,Baer,etc) of the proper size then the chances of having a rotor warp are low. If you opt for the cheap white box crap, well then you get what you pay for.

2) Drum brakes warm up faster in very cold weather.

For a road going car do you don’t want your brakes warm or hot.

3) Loose gravel stones wedged between the rotor and calipers will cause damage.

Possible, I suppose, but I’ve never had it happen to me, and nor have I ever seen it happen first hand to anyone else.

4) When driving through wheel-deep water, disc brakes (especially with metal-based pads) do not work as well as drums until the rotors spin the water off

Actually with drums water and gunk tends to get trapped inside the housing, With discs all you have to do is tap the brakes a few times to dry them off. There’s no comparison.

5) When used as a parking brake, rear drums tend to work better.

This is true, most cars even with 4 wheel disc brakes retain a small drum brake that’s used for the parking brake.

6) Disc brakes rely on pliability of caliper seals and slight runout to release pads, leading to drag, fuel mileage loss, and disc scoring. Drum brake return springs give more positive action and, adjusted correctly, often have less drag when released

Drum brakes tend to have better intial bite, but it’s all downhill after that. And there are more moving parts in drum brake, As for the release I’ve seen both disc and drum brakes seize, once back about 20 years agao when one of the rear brakes on dad’s Caravan decided it didn’t want to disengage (it had gotten water in it and that water froze during the night and when we left in the morning the wheel dragged for about half a mile (snow covered) roads before dad decided it would be prudent to return home. On my F-150 I had the front passenger side brake (disc) stick once, the wheel turned, but you could tell the brake hadn’t fully released. The next day I took it my mechanic (it drove fine on the way there) and they said the rotor was definately overheated, but it wasn’t warped, and they could’ve find the reason for the brake sticking, as it was working fine for them.