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How can they generate less heat when the break function is to turn movement energy via friction into heat? Energy needs to go somewhere and vibration and usuall
by heisenbit 3y ago
How can they generate less heat when the break function is to turn movement energy via friction into heat? Energy needs to go somewhere and vibration and usually noise are not enough to make much of a dent wrt. energy.
- bluGill 3y agoBecause they have more mass they do not get as hot for equal stopping force. However they generate the same amount of heat, it is just spread over more mass so it isn't as hot. That is also their downside: once they get hot they don't dissipate it as well and so they get brake fade faster in typical use.
- monkeynotes 3y agoThey don't fade until a threshold is met. This threshold is much slower onset than rotors because of all that mass. But once it's up to temperature they do fade just like rotors and they will struggle to shed that heat quickly. That's why drums are not useful on high performance cars.
- monkeynotes 3y agoDrum brakes generate heat across a larger surface area, which means there is more surface area to dissipate the heat, under normal braking conditions. Technically as much energy is generated, but the heat dissipation is better in regular usage. Problem with disc brakes is they have a much smaller contact surface and the heat in the area where the calliper pinches is very focussed. Shedding that heat is much more inefficient as the steel takes a while to conduct the energy to the rest of the rotor. This is why brake fade happens much quicker for those brakes, and why there is a lot of tech on fancier disc brakes for shedding that heat. Another benefit of drum brakes is as they heat, they expand and push the drum tighter to the pad, effectively helping you brake harder as they start to fade.