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Discussion in 'The Garage' started by MudNurI, Aug 16, 2002.
Why do those of you that run them use them.....
and those of you that don't- why not????
Look into the cost of changing out the brakes and whats involved on a 14 bolts and you'll see why. Also some weight loss and it stops much much better.
What he said and disc's are easeir to work on no dam springs to fly off and hit you.
ever see the drum on a ff14b? good gawd, them things could stop an anti-tank rocket!! /forums/images/icons/wink.gif heavy as hell, and the weight loss is the main reason I would do the swap. I dunno about the stopping power comparison... I know in normal conditions discs work better, but what about when mud is caked all over 'em?
<font color="green"> Discs clear mud pretty well, have your front brakes ever been packed so bad that they don't work? Drums are worse when they get mud in them since you have to pull the drum to get the mud out. Discs stop better, have better modulation and a much better resistance to fade, weigh less, are easier to work on, etc, etc. Drums have no advantage that I am aware of, other than the fact that if you want them you already have them /forums/images/icons/grin.gif . </font color>
well, drums do have a larger surface area on the actual breaking surface dont they?
<font color="green"> The actual pad surface is higher, but it seems to me that the actuation method is not as efficient. Discs clamp down on a surface with the pads opposing each other, drums have to push out on a spinning drum. I mean the fact is, if drums are better then why does everyone convert to discs, and why did auto manufacturers move away from drums in favor of discs? Just read some articles on cars that have had the rear brakes converted to discs and look at the difference in stopping distance. Have you ever driven an old car or truck with all drums? They don't exactly stop on a dime...</font color>
In my oppinion, the reason drums aren't run on newer cars is that they're noisy. Seriously, why do dump trucks, and even brand new Tractor Trailers use them? Even in the front? Yah, the school busses are noisy, but they're brake systems are very affective. I'm not in any way bashing discs, cause I personally would prefer to work on disks all day long over drums, but I don't know exactly how much more affective they are. Just my $.02 /forums/images/icons/confused.gif
<font color="green"> Wouldn't the drums on those trucks be a pretty different animal? I mean, those guys are using compressed air as an actuator, are they not? I don't know much about those brakes, maybe 70~K5 can shed some light on them... I could be way off base here, but seat of the pants to me says discs are better. I prefer tehm jsut because my old drums gave me such hell, I had to constantly clean them because they would fill with mud or sand, depending where I was wheeling.</font color>
All i know when i had drum brakes i couldn't stop for Sh!t
with rear disc's with my 44's i can lock them up...my 2 pennies <font color="red"> 1 FN HI K5 </font color>
<font color="blue">I have disks on my 14 and they stop good. The main reason I got them was because when I got the axle, the shoes were frozen to the backing plate and most of the hardware was missing. They also don't pack up with mud like drums do
- Simple design, cheep to manufacture, relitivly trouble free (more or less), efficiant.
- Drum brakes are "self-engergizeing", meaning they will self-applie and need far-less in-put force to activate them when compared to disk-brakes. This is why they are commonly used on H/D applications, like trailers and big-rigs. The self-energizeing feature of drum brakes is so efficient that they can applie a large ammount of brakeing force (friction) with very ittle in-put force (I.E. parking brakes a Silverado H/Ds and other current production vehicals)
- Drum brakes do not disapate heat very-well, and will fade quicker than disks. (brake fade is due to a thin layer of heated air between the brake lineings and the brake surface)
- Drum brakes are "sealed" so dirt and grease will get packed inside- contaminating the lineings and effecting brake application, possibly causeing brake leads or brake pulls to on-side.
- Disk brakes stop straighter, they appile brakeing forces more-evenly from side-to-side (L -vs- R) (unlike drum-brakes)
- Disk-brakes disapate heat very-well, brake surfaces are exposed to out-side air and therefore are less likely to overheat and fade. This is why they are used on high-perf rides like sport-cars and raceing applications, where repeated brake appliocations would build up alot of heat over an extended time.
- With the rotor spining at a high-rate of speed, and the wiper action of the brake pads, disk-brake are self-cleaning. They are less likely to be contaminated. All-though, with brake-surfaces exposed it is possible to saturate the brakes (for example, haveing no brakes after going through a puddle of water)
- Fairly complex system, some systems are expensive to build (multie pistion calipers, vented rotors, ect..)
- Disk brakes require alot of applied in-put to activate them, the more brakeing force that is needed, the more in-put force is needed (un-like drum-brakes). This is why parking disk brake systems do not hold very-well, there isn't enough force to achive the friction needed to hold.
i BELIEVE the reason the drums are on big rigs is a simply mechanical. can anyone think how air calipers would work? i think the drums are pushed out by an eliptical lobe pushed by an air ram.
this is all a big "I THINK"
but drums DO give more weight over the drive tire /forums/images/icons/wink.gif im just trying to justify them in my mind
Yeah, I'm kinda "ify" on why they use drums on the big-rigs too, the only thing I can think of is the "self-activating" thing.
Heres one for you guys, i work for a construction company, i sand and paint all the equipment, well they have a big Volvo 6x6 in there with like 6ft tall tires, the front appears to have drums while the rear 4wheels have huge a$$ disc!! weird aint it, plus i think they are running two caliper on each one!!!! and they are still air operated!!! talk about stopping power.
big rigs do not employ any self activating.
they are cam actuated with each shoe a seperate piece not connected.
they are the worst brakes you will ever encounter.
when they get hot the drums expand and you lose your braking ability
Europe I believe has mandated ABS disc brakes on its commercial vehicles.
the ABS rigs I have driven (Kenworths) are terrifying when unladen.
the system simply turns your brakes off.
I have nearly crashed through intersections at your typical 'light went yellow' hard stop
I can threshold brake way beyond the ABS system and would rather scuff a trailer tire then roll through a red light downtown
there are and have been for years air disc systems but the economics of scale make them too pricy to break through the market despite being better in every way.
once they are available en mass the price should drop below or equal drums
Ah- I see.
It's a economics thing, the drums brakes are cheeper.
Pretty crazy when you think about it, they are after all $100,000 (?) rigs
- you would think there would be some room in the budget for some decent brakes.
The main reason I switched to rear discs is because the drums got packed slam full of mud and ate away at the shoes. I would go through rear shoes every 2 months. The discs are self-cleaning and completely remedy the problem.
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