Drums vs. discs

[Sweeney921]

I was just wondering, what are the advantages/disadvantages of drum brakes and disc brakes? Is there anything that drum brakes do better than discs?

[megotmea7]

the major advantage of disc brakes is their ability to quickly cool during at after heavy use. drums are a more contained design so heat soak is a big issue as there is very little air circualtion to cool them down. most of a disk brakes friction surfaces are exposed to a moving stream of air so cooling is much les of an issue, esp. on commuter cars. the advantage of drums however ar they can be setup for no drag which can help in things like drag racing where every tenth of a second counts and repeated hard braking isnt an issue.

[Sweeney921]

interesting, but do disc brakes improve braking distances?

[jcp123]

As far as I know, yes. They also have more swept area, as I understand it, than drums do, and fading even inside the same braking run (start to finish) is far less. Having driven Mustangs with manual AND power drums and discs (gives a fairly even basis for comparison), the discs also seemed to have much better responsiveness vs. the drums. Also, even with power drums, I was never able to lock up the wheels, where the power discs I have now have no trouble doing it, so it seems the discs just have more bite, too.

Personally, I liked the feel of the manual discs best; good responsiveness and feedback.

[Egg Nog]

For the past many few decades, most cars used discs at the front and drums at the back. I believe this was because it was easier to put a powerful brake up front and a weaker one at the back to get the desired brake application than it was to have powerful ones all-around and have a finicky proportioning valve. A lot of sports cars (including the 914 ) would use 4-wheel discs just because it would give better performance overall.

[jcp123]

If it weren't so expensive, I'd love to ger 4-wheel discs on my car...

[Sweeney921]

A lot of sports cars (including the 914 ) would use 4-wheel discs just because it would give better performance overall.

and the volvo 850 . It's very surprising how big the diameter of the discs are, I might go outside and measure them tomorrow, since it's dark outside here.

[Niko_Fx]

Drums are also cheaper. So on a Honda Civic, which is not a heavy car and with poor acceleration they fit well. My car breaks pretty good I must say, no problem whatsoever when braking.

[TheOne]

my eclipse breaks fine, it has discs at the front and disc/drum at the back(dunno why but yeh, its a disc/drum at the back)

[KnifeEdge_2K1]

the internal geometry of drum brakes allows an easier hand brake/ parking brake setup since there'll be no need to have internal drums inside each hub or axle where as the handbrake mechanism can be intergrated to the drum brakes themselves, also this setup (drum brakes) provide alot of the braking power themselves which means a vacumm (i think thats what its called) booster isnt needed, however the disadvantages drumb brakes have outweigh the advantages by far

the reason why most cars (in the not so distant past) used drums in the rear are because on the road you want more braking power in the front then the rear because of the weight transition, locking the rear tires under braking can be possible if the brake bias isn't right, however 4 wheel disk brakes and abs system in today's cars can accomplish the same feat which is why we're seing dum brakes being faded out

[PerfAdv]

Major advantages/disadvantages given above but also consider:
-drum brakes are cheaper to service and in a commuter vehicle where high performance is not an issue, are an acceptable substitute.
-drum brakes, as the name implies is sort of an enclosed cylinder. Heat buildup is an issue and they can also hold water. In a vehicle that might have to operate in water at a boat dock for example, will flood their brake drums with water and braking power will be reduced until the water drains. With street flooding this would also apply.
-For alloy wheels designs which show through, a drums setup in the back is unsightly.

[henk4]

For the past many few decades, most cars used discs at the front and drums at the back. I believe this was because it was easier to put a powerful brake up front and a weaker one at the back to get the desired brake application than it was to have powerful ones all-around and have a finicky proportioning valve. A lot of sports cars (including the 914 ) would use 4-wheel discs just because it would give better performance overall.

The Citroen GS was already fitted with 4 discs when it got into production in 1970.

[jcp123]

'71 and up Cadillac Eldorados featured 4-wheel discs, with other Cads not far behind and I could be wrong but Corvettes might have had 4-wheel discs before '70, too

[henk4]

'71 and up Cadillac Eldorados featured 4-wheel discs, with other Cads not far behind and I could be wrong but Corvettes might have had 4-wheel discs before '70, too

I mentioned the GS because it was a mass produced small car. There were alerady many European top sportscar fitted with four discs and also the Renault R8 from the sixties, but I can't remember by head wether it had 2 or 4.

Anyway, the use of drums at the rear was considered to be cheaper at the time and that's why they kept on being used so long.

[jcp123]

Oh, ok.

Yeah, until today even. My car even uses the disc/drum combo straight off the '77 Granada we jacked the brakes (and a bunch of other stuff) from.