After spending most of yesterday covered in sweat and brake dust, all the while cursing at all manner of springs that you can't reach and spring tools that can't actually remove or replace them, I had to wonder - why do drum brakes even still exist for most of us? Backstory - I had to call in to my summer job fixing golf carts (the joys of a high school teaching career) to say I'd be an hour late as replacing the shoes on my girlfriend's Kia was 3/4 done in 3x the time I'd expected it to take. He said no problem - then presented me with a couple of brake replacements on carts when I rolled into the shop. [bang]
The Kia was a piece of work, as apparently one of the primary engineering objectives was to make it impossible to work on. It was a whole mess of powerful springs in awkward places, most of which had to be set blind and on which none of the impressive array of brake spring tools I had at my disposal (my boss at the golf car place used to be the local Snap-On dealer, so...) would work. The E-brake attachment was one of the funkiest puzzles I've ever seen, one I finally solved with a pair of Vice Grips, C-Clip pliers, two sets of hands, and a whole lot of trying over, and over, and over.
The golf carts were easier - lighter to sling the parts around, at least - but adjustment was a pisser. Because torquing the wheel onto the hub changed EVERYTHING about the adjustment, you couldn't get them set with the wheel off... but you couldn't reach the adjusters with the wheel on.
And with every smashed knuckle and spring that went flying across the shop, I remembered life with my 1973 Land Cruiser with drums at all four corners. Even with the brakes in tip-top condition & adjustment, stopping was a leisurely affair in that truck, and after any stream crossing I'd just assume I had no brakes at all. Drum brakes just suck.
I'm sure there are better ways to do both of these jobs than I did and Kia special service tools that would be in a dealer's arsenal (but probably not in most professional shops), but every single one of the professional mechanics I asked despises working on drum brakes and can't think of a single reason why they're still used so widely on passenger cars.
Running an E-Brake with a cable may be relatively easier with drums, but plenty of engineers have figured that one out. Drag racers used to prefer them because they used to have lower rotating mass and you could set them up with zero drag (which has nothing to do with the design needs of a Kia minivan).
So why do we still have to deal with these pieces of cutting edge 19th century technology? Discs are cheaper to manufacture, take less labor to install at the factory, cost less for the dealer to service, perform radically better and, perversely, would allow car makers to charge a little bit MORE for a performance upgrade for at least a few years.
Why drum brakes in the 21st Century?
Quote from: triangleforge on June 19, 2015, 08:26:43 AM
After spending most of yesterday covered in sweat and brake dust, all the while cursing at all manner of springs that you can't reach and spring tools that can't actually remove or replace them, I had to wonder - why do drum brakes even still exist for most of us? Backstory - I had to call in to my summer job fixing golf carts (the joys of a high school teaching career) to say I'd be an hour late as replacing the shoes on my girlfriend's Kia was 3/4 done in 3x the time I'd expected it to take. He said no problem - then presented me with a couple of brake replacements on carts when I rolled into the shop. [bang]
The Kia was a piece of work, as apparently one of the primary engineering objectives was to make it impossible to work on. It was a whole mess of powerful springs in awkward places, most of which had to be set blind and on which none of the impressive array of brake spring tools I had at my disposal (my boss at the golf car place used to be the local Snap-On dealer, so...) would work. The E-brake attachment was one of the funkiest puzzles I've ever seen, one I finally solved with a pair of Vice Grips, C-Clip pliers, two sets of hands, and a whole lot of trying over, and over, and over.
The golf carts were easier - lighter to sling the parts around, at least - but adjustment was a pisser. Because torquing the wheel onto the hub changed EVERYTHING about the adjustment, you couldn't get them set with the wheel off... but you couldn't reach the adjusters with the wheel on.
And with every smashed knuckle and spring that went flying across the shop, I remembered life with my 1973 Land Cruiser with drums at all four corners. Even with the brakes in tip-top condition & adjustment, stopping was a leisurely affair in that truck, and after any stream crossing I'd just assume I had no brakes at all. Drum brakes just suck.
I'm sure there are better ways to do both of these jobs than I did and Kia special service tools that would be in a dealer's arsenal (but probably not in most professional shops), but every single one of the professional mechanics I asked despises working on drum brakes and can't think of a single reason why they're still used so widely on passenger cars.
Running an E-Brake with a cable may be relatively easier with drums, but plenty of engineers have figured that one out. Drag racers used to prefer them because they used to have lower rotating mass and you could set them up with zero drag (which has nothing to do with the design needs of a Kia minivan).
So why do we still have to deal with these pieces of cutting edge 19th century technology? Discs are cheaper to manufacture, take less labor to install at the factory, cost less for the dealer to service, perform radically better and, perversely, would allow car makers to charge a little bit MORE for a performance upgrade for at least a few years.
Why drum brakes in the 21st Century?
they are supposed to keep costs lower . . . labour costs go up . . . ask rotor head . . . I HATE DRUM BRAKES !!!
Rears do like 10% of the braking so don't see a lot of wear, and it's substantially easier to install one brake that functions as both a regular and parking brake vs installing a set of discs and a separate caliper for the parking brake. Especially considering most people don't use the parking brake and the rear brakes are basically along for the ride.
Performance improvement is minimal with the change, esp on a budget minivan. As far as cheaper to work on-this is just the factories way of making sure their dealer service departments make some money.
I can probably paraphrase Kia's unofficial stance for ya:
"It's cheaper-make the beast with two backs you"
Or, if they don't feel like consulting a bean counter, "make the beast with two backs you".
Please let me now if you have any other questions re: modern day manufacturing/corporate America. :-*
Quote from: Satellite smithy on June 19, 2015, 10:02:51 AM
I can probably paraphrase Kia's unofficial stance for ya:
"It's cheaper-make the beast with two backs you"
Or, if they don't feel like consulting a bean counter, "make the beast with two backs you".
This is awesome! [laugh] [clap]
Craslo sends me frequent PM's asking if he can come back to town and fix my brakes again.
;D
Sometimes a have to question what he means by "FIX" [evil]
jajahajajajajajajajaja
My Dakota came with drum rear instead of disc. Dodge said because I had the towing package and heavy duty suspension I got the drums instead of the discs. They're explanation was due to the truck being equipped for heavier hauling with the towing equipment and heavier suspension and that drums are much better and managing a heavy load.
It makes some sense, since the air brakes that most buses and heavy trucks & tractor trailers are drum (air instead of hydraulic of course). However, I don't image the heavy load part applies to any Kia.
JM
Quote from: the_Journeyman on June 19, 2015, 12:01:25 PM
My Dakota came with drum rear instead of disc. Dodge said because I had the towing package and heavy duty suspension I got the drums instead of the discs. They're explanation was due to the truck being equipped for heavier hauling with the towing equipment and heavier suspension and that drums are much better and managing a heavy load.
And you believed them? :D
Next up on Corporate Mothermake the beast with two backser: we'll teach you how to convince the peons that the bugs are features!
Nobody buys a Dakota to tow with. They had a deal on $5 trailer hitches that week and added on a $500
tow package. Likely they added it to every Dakota made so they could charge more and give you no option about buying said package.
They're all evil.
We should shun Randimus on principle.
Quote from: the_Journeyman on June 19, 2015, 12:01:25 PM
My Dakota came with drum rear instead of disc. Dodge said because I had the towing package and heavy duty suspension I got the drums instead of the discs. They're explanation was due to the truck being equipped for heavier hauling with the towing equipment and heavier suspension and that drums are much better and managing a heavy load.
Sounds like BS to me. My Chevy has a 17,000 lb tow capacity, and the truck itself weighs about 7,500 lbs...discs all around.
Quote from: Satellite smithy on June 19, 2015, 12:36:39 PM
Nobody buys a Dakota to tow with.
I do. Plenty, and usually push it's ratings both in towing and payload.
Quote from: Triple J on June 19, 2015, 03:18:58 PM
Sounds like BS to me. My Chevy has a 17,000 lb tow capacity, and the truck itself weighs about 7,500 lbs...discs all around.
Heavy trucks have drums. Our bus mechanics say that drums are more durable and lower maintenance than discs on heavy stuff. I've seen a few motor coaches with front air powered discs, but not many.
JM
I have no doubt that corporate bean counters could not care less about my sweat and imaginative cursing. The thing I don't get is that discs (plebeian, simple things rather than high performance parts) are cheaper than drums. For the Kia minivan in question, the aftermarket rotors are $45, while the discs are $55. Granted that's aftermarket, but I don't imagine the cost differential goes the other way with OEM parts.
And if corporations have little regard for the consumer, just think how much less they have for the line workers who put the stuff together and his/her desire for full employment. Even with a professional auto worker using very specialized tools (or for that matter, an assembly robot) is going to take longer to put together a drum brake than a disc on the assembly line. More parts, more steps, more fussy bits to line up.
I get that long haul trucks and buses have different needs, along with professionals who always do the service. Again, I'm not hoping that Detroit/Seoul/Toyota City (yes, it's a place) will ever care a whit about me and my problems. I still just don't get how drums are still the cheaper alternative.
Quote from: triangleforge on June 19, 2015, 06:55:44 PM
I have no doubt that corporate bean counters could not care less about my sweat and imaginative cursing. The thing I don't get is that discs (plebeian, simple things rather than high performance parts) are cheaper than drums. For the Kia minivan in question, the aftermarket rotors are $45, while the discs are $55. Granted that's aftermarket, but I don't imagine the cost differential goes the other way with OEM parts.
And if corporations have little regard for the consumer, just think how much less they have for the line workers who put the stuff together and his/her desire for full employment. Even with a professional auto worker using very specialized tools (or for that matter, an assembly robot) is going to take longer to put together a drum brake than a disc on the assembly line. More parts, more steps, more fussy bits to line up.
I get that long haul trucks and buses have different needs, along with professionals who always do the service. Again, I'm not hoping that Detroit/Seoul/Toyota City (yes, it's a place) will ever care a whit about me and my problems. I still just don't get how drums are still the cheaper alternative.
Spoken like an artist. ;D
Most drum brakes have an advantage for stopping large vehicles by what is called servo action, hard to put into words, but google will help those whom are curious. As the shoe material contacts the drum the leading, or, in the case of the Bendix (duo servo) type brake, both shoes wedge into the drum exerting more force. A good example is an old high performane bike with four leading shoe drum up front. Properly adjusted? Instant lock up. Disc brakes do not do this. Power brakes make servo action not needed, and sometimes undesirable. Drum brakes also work better as a parking brake because of servo action. This is why some heavy vehicles with rear discs use a mechanical drum brake integrated into the rotor as a parking brake.
In today's world of power brakes and electrohydraulicilly applied parking brakes not much justification for cars and light trucks. ABS also works much better with disc brakes. Needless to say lack of mechanical fade (drum expansion) and water fade are additional benefits.
Back to the Kia in question. Most likely $$$. Disc brakes become more expensive once you incorporate a parking brake plus you don't get to use up the leftover parts on the shelf.
To save the curious the work:
http://www.hemmings.com/hmn/stories/2013/09/01/hmn_feature19.html (http://www.hemmings.com/hmn/stories/2013/09/01/hmn_feature19.html)
https://en.wikipedia.org/wiki/Single-leading-shoe_drum_brake (https://en.wikipedia.org/wiki/Single-leading-shoe_drum_brake)
Quote from: howie on June 19, 2015, 08:06:50 PM
This is why some heavy vehicles with rear discs use a mechanical drum brake integrated into the rotor as a parking brake.
My dad's Silverado had that exact setup for the parking brake.
JM
Quote from: the_Journeyman on June 19, 2015, 05:43:56 PM
Heavy trucks have drums. Our bus mechanics say that drums are more durable and lower maintenance than discs on heavy stuff. I've seen a few motor coaches with front air powered discs, but not many.
Understood. Your Dakota isn't a heavy truck though, nor is my 2500. Discs work fine, so the reason you were given most likely wasn't true. That's all I was saying.
Drum brakes are the devil. Luckily they don't need to be replaced that often. It is not just Kia ether, Toyota still puts them on the Tacoma.
Quote from: Satellite smithy on June 19, 2015, 12:36:39 PM
We should shun Randimus on principle.
Hey. >:(
You know I don't call any shots.
And TF stills me a beer that I was never able to connect with him on. :P [beer]
Quote from: Randimus Maximus on June 20, 2015, 06:33:10 PM
Hey. >:(
You know I don't call any shots.
And TF stills me a beer that I was never able to connect with him on. :P [beer]
You saying Akio was ordering all those shots for you that night? [shot]
The drums on my Datsun have about 6 parts. Two springs, two spring retainers, two shoes, then the drum. They're not bad. They stop about like Fred Flintstone brakes though. If I relied on them I'd be dragging my boots to stop!
JM
Quote from: Rotor Head on June 20, 2015, 06:37:32 PM
You saying Akio was ordering all those shots for you that night? [shot]
Which night?
Quote from: the_Journeyman on June 20, 2015, 06:40:26 PM
The drums on my Datsun have about 6 parts. Two springs, two spring retainers, two shoes, then the drum. They're not bad. They stop about like Fred Flintstone brakes though. If I relied on them I'd be dragging my boots to stop!
JM
wished I had the $$ to get your Datsun and rebuild-remanufacture it . . .with some perf enhancements . . .
This message is hidden because Randimus Maximus is on your ignore list. [cheeky]
My old Cougar has 4-wheel drums. Stellar braking performance. :P
I've driven my new Mustang after driving it and almost put myself through the windshield the first time I brake..... [laugh]
I remember learning years ago another economic reason for the continued use of drum brakes on cars and trucks. Disc brakes are pretty much intolerant of axle end play and drum brakes will work with some axle end float, allowing the use of a cheaper bearing system. Not sure if the present rear axle drum brakes are mostly all on old school rigid axles but it seems that way. Newer cartridge style wheel bearings are usually found on disc brake systems?
Bob
Quote from: Langanobob on June 26, 2015, 02:57:24 PM
Not sure if the present rear axle drum brakes are mostly all on old school rigid axles but it seems that way.
Very possible. My truck is independent suspension with the two half-shafts, while the rear is a solid axle. Not modern, but my 280Z is the exact same configuration.
JM
On the topic of price, you were saying that drums are more expensive than rotors...
But last time I checked, calipers were a hell of a lot more expensive than wheel cylinders.
Quote from: Langanobob on June 26, 2015, 02:57:24 PM
I remember learning years ago another economic reason for the continued use of drum brakes on cars and trucks. Disc brakes are pretty much intolerant of axle end play and drum brakes will work with some axle end float, allowing the use of a cheaper bearing system. Not sure if the present rear axle drum brakes are mostly all on old school rigid axles but it seems that way. Newer cartridge style wheel bearings are usually found on disc brake systems?
Bob
Quite true!
If you deal with drum brakes much.
Take an old spoke (talk to one of you motocross riding friends) and a chunk of broom handle.
1) Drill a 1/8' hole cross ways thru a 6' piece of broom handle in the middle.
2) Slip spoke thru hole and put spoke nipple back on.
3) cut spoke to length (6' to 12")
4) heat other end up with torch and bend a nice hook.
5) file end of hook sharp
You now have something that will grab a spring and allow you to pull to your hearts content while keeping your hands away from sharps edges waiting to cause blood loss, and much cheaper than what Snap-On charges for the same basic thing.
Quote from: sno_duc on July 06, 2015, 06:06:53 PM
If you deal with drum brakes much.
Take an old spoke (talk to one of you motocross riding friends) and a chunk of broom handle.
1) Drill a 1/8' hole cross ways thru a 6' piece of broom handle in the middle.
2) Slip spoke thru hole and put spoke nipple back on.
3) cut spoke to length (6' to 12")
4) heat other end up with torch and bend a nice hook.
5) file end of hook sharp
I thought for sure that step 6 was going to be, "poke sharp hook into eye". [laugh]
Actually, that's step one - might as well start the suffering early.
Quote from: Autostrada Pilot on July 13, 2015, 12:07:09 PM
I thought for sure that step 6 was going to be, "poke sharp hook into eye". [laugh]
My car wrenching started in the early 70's, back when most of the cars that high schoolers could afford had drum brakes. After a couple of learning experiences that involved brake springs and me getting perforated, plus basic cheapness (only made $1.25 an hour, most of which went to keeping my dirt bike running), led to a home made tool that works quite well.
I like this topic of Complaining about Drum brakes. I had a few cars with drums and well....lets not talk about that, gives me a headache and my knuckles start to hurt just thinking about it.
But I'm glad it's not just me that felt the pain & sweat when fooling around with the things.
So I had a CR250R with a drum on the back. It was pretty easy to change the shoes on that. braked OK too. I just didn't like the the squeal that emanated from the rear wheel area when using the back brake.
Whine whine whine about modern day drum brakes.
Go work on some that are not self adjusting and you'll appreciate the new ones.
Also I just use a pair of wire snips to extend the brake spring. They dig in enough for purchase but don't hurt the spring.
I think I will just stick with Disks.
BTW I was under a car recently and noticed how the parking brake was a drum brake mounted on the drive line.
Quote from: Satellite smithy on July 24, 2015, 05:03:04 PM
Go work on some that are not self adjusting and you'll appreciate the new ones.
You mean like my '73 Land Cruiser FJ40 that had drums on all four corners? I miss that truck, but don't miss fishing around for the click wheel through the backing plate, wondering if I'd moved the stupid thing at all, and repeating on all four wheels until I gave up in exhaustion. And every so often there on the East Coast, you'd get one that was rusted into a frozen lump.
Nope, don't miss those days at all, but still isn't enough to make me appreciate the slightly updated out-of-date technology. ;D
Says the guy with an anvil in his avatar. :-*