If I can stop a 6Klb Cadillac with drums then rear drums and front disks are fine for like 90%. What full disks do better is stop straight every single time and don't require adjustment for balance and force.The number of people who can really setup drum brakes all round are dwindling.
alfadriver wrote:Woody wrote:No- hypothetical. Bear in mind, there are already a LOT of cars with 4 wheel drums- and I know one that ran in the challenge like that.alfadriver wrote:Do you foresee that happening?Woody wrote: No vehicle deserves to have drum brakes, not even Satan's own Hyundai.So if someone gave you a car with 4 drum brakes, you would turn it away, regardless of the car?
Let me ask you this:
Is there a vehicle on which you would prefer to have drum brakes over discs? (Not, "Are there cars that you would like to own that only came only with drum brakes...")
Is there a car that came with discs that you would consider swapping to drums?
Drums are better parking brakes and have more pad to braking surface area than disks. Why do heavy rigs use drums instead of disks.
Woody wrote:alfadriver wrote:Let me ask you this: Is there a vehicle on which you would *prefer* to have drum brakes over discs? (Not, "Are there cars that you would like to own that only came only with drum brakes...") Is there a car that came with discs that you would consider swapping to drums?Woody wrote:No- hypothetical. Bear in mind, there are already a LOT of cars with 4 wheel drums- and I know one that ran in the challenge like that.alfadriver wrote:Do you foresee that happening?Woody wrote: No vehicle deserves to have drum brakes, not even Satan's own Hyundai.So if someone gave you a car with 4 drum brakes, you would turn it away, regardless of the car?
I'd think that drums are preferable only in certain industrial/commercial applications--heavy duty towing and similar. I'm not sure where I read that or why I think that.
That is the only one I can think of though.
Fueled by Caffeine wrote: Drums are better parking brakes and have more pad to braking surface area than disks. Why do heavy rigs use drums instead of disks.
Drum brakes can supply more braking torque into the same volume. This is why heavy duty trucks still use drums.
Drum brakes are self energizing. This is their benefit and their downfall - they can be very nonlinear with respect to speed. More speed means more braking for the same amount of pedal force. This also makes them much more prone to locking up. This is why front drums is kind of sketchy.
They CAN overheat more easily, but heavy trucks have this NEAT feature where they use exhaust backpressure to slow the truck down, in effect dissipating the braking heat through the engine's radiator.
Design for your priorities, not an arbitrary features checklist.
In reply to mtn:
I believe you are right. For example, drums are good on a truck. Reason is they have tons of power to stop a vehicle and generate a lot of heat really fast. Bad news is they can only do it once or twice before overheating.
So they are good for one emergency stop of like 80k lbs. They are not great for endurance racing said truck.
Semitrucks is your answer. Archaic motorcycle is mine.
I will admit that I prefer mechanical drum brakes on old dual sport motorcycles.
AIUI, in addition to the heat problems, drums also have problems with not drying out as quickly as discs do.
Good for a train, good for electric trailer brakes, lousy for a race car, acceptable as rears for a street car if you're willing to live with the fact that you'll never get them balanced properly against the fronts without electronic assistance in the form of ABS.
The only drums I own are on my trailer, and I plan to keep it that way.
Alfa says "no cost" like a guy doing advanced projects, not a guy in a plant. ;-).
If it's a unique calibration, it had a development cost which was probably amortized into the piece price over 1-3 years.
If it has a unique part number, even a calibration file that is flashed into the ECU by a VIN-reading robot on the assembly line, it has a cost to the plant because it has to be failsafe.
If it's a hard part with a unique part number, for sure it has cost because it has to be received, inspected, stored, sequenced, and assembled with zero tolerance for mis-builds, lest that vehicle have even more cost tied to it by way of "heavy repair" at UAW rates.
Bottom line is drums are cheaper, more effective, and they park. Discs have an image.
Truth be told, I'm without an opinion. I'm fine with drums on the rear of a FWD econobox.
I sold my '05 Scion with 92k and the shoes still looked swell, with plenty of meat on them. When a car has something like a 65/35 weight distribution, the rear brakes don't do much anyhow.
I was thinking about power windows, which all but the most basic cars have nowadays. At some point manufacturers decided that it was cheaper to put p/w on every trim level, rather than having to build/stock two separate systems.
Our new buses all come with disks. The pads are smaller than I expected.
I've been able to get a better pedal 'feel' out of rear drums over disc. Also, no pad knock-back.
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