Kenworth started putting disc brake on their tractors in 2001 or 2, and with the new stopping regulations you’re going to see more and more. Contract Freighters Inc.said in 2004 their tractors would have disc brakes. In 2012 there are standard equipment for Peterbilt,
Rick, no disrespect meant, you’re obviously interested in cars, let me suggest that you sign up for some basic courses. there’s a lot to learn, and that’s a great way to learn it. It appears that all your points have been responded to, so I won’t belabor the details. I confess that I didn’t browse the thread, because the initial post suggested to me that while mechanics interests you, your points indicate a lack of understanding of how brakes work .
I will give Rick one point - rear drum brakes are fine for most cars, so little braking is done by the rear brakes, anyway.
I owned a car with disk brakes in the front and drum brakes in the back. The car was rear wheel drive. The axle seal leaked and the oil coated the inside of the brake drum. My son was a young driver and said for him the car was a handful when he would brake–similar to being on ice. This wouldn’t have been a problem if the rear brakes had been disks and the axle seal leaked grease.
I’d be inclined to agree, Texases, as long as you don’t go through a puddle. The centrifugal force keeps the water in the drum rather rather than throwing it off.
I remember the days of wet drum brakes. Argh!
Just one more little comment, large aircraft do not use disk brakes, but they certainly don’t use drums either. They use a system that resembles a multi-plate clutch.
@keith - you’re correct, but I guess I might call them ‘multi-disk brakes’, at least they’re a lot more similar to disks than drums (737 brakes here):
Having done brake jobs on both disc brakes and drums, I’d rather have disc brakes any day. Reassembling drum brakes can take a while, especially if you haven’t done it in a while. However, doing a disc brake job takes me about 15 minutes on each wheel. The last time I did a brake job on my rear brakes, which are drums, it took me about 45 minutes per side to get everything back together, and that’s even with the special tools that are supposed to make the job easier. To do a brake job on disc brakes, you don’t need special tools, although they are available.
One more advantage for discs is that, if you keep your car long enough, the brake cylinders on the drum brakes will leak and need to be replaced. Calipers on disc brakes aren’t as likely to leak.
Keith and Texases, you’re both right.
Drums could not possibly dissipate heat effectively enough for a large aircraft.
Contrary to the OP’s assumption, disc dissipate heat much better than drums, both in that they allow the frictional surface to be exposed to the air and in that they allow the pads to be exposed to the air. Drums keep the heat of braking contained…and, unless you’re driving regenerative brakes (Prius), than 100% of the vehicle’s kinetic energy is converted to heat.
“When I drove my 68 camaro every day it kept me on my toes, no power steering, no power brakes, and I drove it like a maniac, kids now a days couldnt handle that car. One time I was hopped up on goofballs, driving down a mountain pass going 110, and I didn’t downshift like you should, which I knew better, well anyway I got the scare of my life as when I finally got it stopped there was smoke rolling from all 4 wheels, It taught me a lesson I will never forget, Downshift.”
That’s an interesting testimonial, I believe a late model Camero with disc brakes can stop from 110 MPH without such a dramatic display.
All that heat trapped inside the drum will take its toll on the wheel cylinder seals. If not inspected and maitained can lead to a hydraulic failure as Rick described on page 5.
@whitey Whitey thats why I like drums, when you replace them it takes a while and you get to think of all of the times you used the brakes when you didn’t need to, so it reminds you not to hit the brakes all of the time or ride them.
Brakes are brakes, driving since 68 yes in wet conditions you would do a few tests of the brake before you needed them, but never felt one was superior to the other in avoiding accidents. They both stopped my car just fine, the downside to disk brakes is torquing correctly to prevent warping, no big deal except for the people that need to replace rotors prematurely. 86 k on the first set of pads and rotors 4 wheel disk, 147k now and at 50% . Remembering fondly my toyota 2wd pick up, 98k on rear drums, and jokingly saying what you can’t even get100k out of a set of brakes?
“Brakes are brakes”. Yup, if you’ve stepped on one brake pedal, you’ve stepped on them all. I never use the brakes–I just step on the accelerator, use power and drive my way out. (remember that line from “Hotrod”–a book we all read in the 1950s?)
AN ODE TO OUR UNAPPRECIATED FRIEND THE DRUM BRAKE
Drum brakes, drum brakes
when you are only in the back you feel so far away
Ill take you on 4 wheels any single day
Drum brakes, drum brakes
i know i can count on you to stop me any day,
whether hydraulically activated or with applied cables i will take you any day
Drum brakes, drum brakes
they don’t know you like I do, they all think im a fool
but I know your self energizing and when properly sized tend to run cool
Drum brakes, drum brakes
A 110 down the mountain just the other day
I felt absoulute horror when you started to fade,
but you gave it all you had and slowed us down anyway.
Drum brakes, drum brakes
At the side of the road waiting for you to cool down,
as you billowed smoke I had time to think,
and listen to the birds chirp and sing a little song
Drum brakes, drum brakes
Now a days they cast you to the rear,
while our hero the disc is up front pulsating and squealing for all to hear
Drum brakes, drum brakes
what else can I say?
Those who love discs live life a little fast,
but to some, you are a window to the past.
LONG LIVE THE DRUM BRAKE
So there, yes disc brakes have many advantages over drums, BUT how many complaints of pulsation were there back then. Overall disc brakes are better. But drums have/had their place.
UGH…REALLY? You arent SERIOUSLY trying to make this argument …ARE YOU?
As for the CONS of the DRUM? My God man… Arent they all CONS?
Poor Brake control and or modulation
FAR LESS STOPPING POWER?
HEAT FADE?
A USELESS CONGLOMERATION OF SPRINGS…Clips, Adjusters and lots of toxic brake dust waiting for you to revisit the drum
About DOUBLE the number of parts?
Oh and less stopping power…longer distance stops?
Did I mention less Stopping Power?
I often and recently wondered the location of the ENORMOUS Secret Govt WAREHOUSE…Where they stockpiled Billions and TRILLIONS of sets of drum brake components. It MUST EXIST…bec they are STILL trying to use up all the surplus Drum Brake kits they stocked since the early 1900’s…They have been FOISTED upon us for far too long…So send me the Coordinates so we can execute the Drone Strike on this EVIL EVIL Place…PLEASE ERADICATE THE DRUM BRAKE
But SERIOUSLY…Dont try to convince me…Im not important and I know this…I am no one, nothing.
Let all the manufacturers know that you DEMAND Drums on all of your vehicles…See whatcha get…maybe a free lifetime pass to that Warehouse I mentioned? Go for it.
Blackbird
Perhaps I drive a bit like a little old lady but never needed the extra capacity of disk vs drum. Disk brakes are definitely better technology but smart driving trumps technology every day of the week.
@WheresRick–like the south, the drum brakes will rise again! Save your old brake shoes–like confederate money, you will need them.
@barkydog Finally, someone who gets what I have been saying. Drums are just fine, how many people who talk bad about drums actually drove drum brake cars everyday?
Drum brakes were slow to be eliminated from use on automobiles because the industrial capacity to produce them had long been amortized. It was vastly cheaper to continue to produce and use drums on the rear as compared to redesigning and engineering the rear hub and brake assembly.