Why drum brakes?
Why drum brakes?
(OP)
Why do manufacturers use drum brakes on passenger cars/trucks rather than disk brakes? Because of their simplicity, it seems like disks would be cheaper to build plus they stop better. What advantage do they have over disks?





RE: Why drum brakes?
Cheers
Greg Locock
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RE: Why drum brakes?
Add better progression as well.
Drums can fade a lot when hot but that can be helped with modern lining materials and higher pressures.
Bill
RE: Why drum brakes?
RE: Why drum brakes?
Cheers
Greg Locock
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RE: Why drum brakes?
RE: Why drum brakes?
RE: Why drum brakes?
I suspect that the drum brake is pretty much history these days, not because they do not work, but because of advertising's influence on the market---drum/bad---disc/good!
Rod
RE: Why drum brakes?
RE: Why drum brakes?
of braking. You can really notice it when I road raced my old Norton the feel on the drum was a lot better especially trail braking.
Anyways why put disk on the rear and use a brake bias valve to turn them down by at least 40%.
Cheers
I don't know anything but the people that do.
RE: Why drum brakes?
rmw
RE: Why drum brakes?
RE: Why drum brakes?
RE: Why drum brakes?
As to a Norton...I have one of the ES2/International race bikes, converted to street, from 1948 and it has very large mechanical drum brakes that work well...for a 1948 bike. Now for the BEST brakes I have used on a bike, I'll take my old '77 KZ 650's duel front and single rear hydraulic disc brakes....Anytime. I'm sure if they were that good in '77 the advancement in braking on bikes must be better today.
Rod
RE: Why drum brakes?
They are still being used on heavy trucks, yes on the front too...
RE: Why drum brakes?
RE: Why drum brakes?
RE: Why drum brakes?
Drum brakes are on the way out in heavy trucks as well; disc brakes have the great advantage that they can dissipate prodigious amounts of heat to the air.
The big disadvantage of drum brake is that the friction surface is shielded from the air, except in rather specialized racing applications where the backing plates were cut away and air is ducted into them.
The big advantage of drums of course is that they can be designed to be self-energizing and self-adjusting.
There is one more advantage I have not seen mentioned here:
unlike disc brakes, drum brakes have no drag when released, and so contribute to better fuel economy.
RE: Why drum brakes?
Exactly! I had a Saturn with 172k miles and the original rear brake shoes (drum), they were less than half worn. (2150 lb car helps)
RE: Why drum brakes?
If deigned correctly they retract enough to have no more drag than a well adjusted drum.
I would have thought for a front brake, a single spot floating calliper disk is less complicated and less costly than a twin leading shoe self adjusting drum of lesser braking power and similar space requirement. Rear brakes is a whole new ballgame or the reasons Greg mentions.
A rear disk with separate drum for the handbrake does add an extra but probably unnecessary safety factor.
Regards
Pat
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RE: Why drum brakes?
I'm not sure I follow the complaint regarding reducing the rear brake bias by 40%. The harder you stop the less you want the rear brakes to be contributing. But if brake bias is always biased to the front to suit the most severe braking the rears will be under-utilized in easier events (which is arguably the majority of the time for production vehicles).
Norm
RE: Why drum brakes?
I did specify if designed correctly. I know some are no correctly designed.
I would thin it is more important for the brakes to be balanced on the rare occasion that they ar used hard than on the many occasions they are used lightly. I base this on the potential for the cost of the consequences vs the likelihood of the results.
Regards
Pat
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RE: Why drum brakes?
Norm
RE: Why drum brakes?
Just one of the reasons I have an adjustable prop valve on the rear drum brakes...
h
Rod
RE: Why drum brakes?
Regards
Pat
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RE: Why drum brakes?