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There are EV's which have drum-brakes. That's only possible because the regenerative braking takes most of the load. Also, there are stories of brake-discs rust

There are EV's which have drum-brakes. That's only possible because the regenerative braking takes most of the load. Also, there are stories of brake-discs rusting out on EV's. Both point to less (friction)-brake use on an EV compared to an ICE.

robin_reala 2y ago
Yeah, my VE id.3 has drums on the back and disks on the front. Apparently the brake pads are effectively life-of-the-vehicle items under normal driving conditions.
- plasticchris 2y ago
  I’ve only had to change them one time on any car newer than 1990, after ~200k miles/10 years of use. For most people that qualifies as life of the vehicle, but there was plenty of life left.
  - Scoundreller 2y ago
    The drum brakes or the rotors? Certainly not the disk brake pads!
    - plasticchris 2y ago
      Yeah, the pads lasted that long. It was a manual and I did engine break pretty often.
      - plasticchris 2y ago
        * engine brake
m463 2y ago
I suspect drum brakes were chosen by the electron pinching EV engineers. They're the only brakes that are friction-free when not applied. Disc brakes rub (and slow the car) even when not applied.
- kstrauser 2y ago
  Not significantly. Otherwise they’d get hot and work less well. Pads ride very closely to the disc so that road stuff can’t get wedged between the surfaces, and so that you don’t waste break pedal travel just getting the pads close to the surface. Well adjusted drum brakes should be arranged almost exactly the same way. From https://mechanicswizard.com/how-close-should-brake-pads-be-to-rotors/ https://mechanicswizard.com/how-close-should-brake-pads-be-t...: > Typically, the optimal gap between brake pads and rotors is between 0.5 and 1.5 mm (0.020 to 0.060 inches).
  - lukevp 2y ago
    Are you familiar with how disk brakes on a car operate? They’re essentially a hydraulic piston clamping the brake pads against the rotor. When you let off the brake pedal, the pressure is removed, but there’s not a “retraction” of any kind. So there’s no pressure but nothing is actually making that gap. That article was articulating basically that the piston, when not compressing the brake pads, should not be too far out, because that’s just unnecessary travel of the pedal, but it does not mean that the brake pads are somehow gapped away from the rotors. Drum brakes by contrast have springs that retract the pads from the braking surface, so the OP has a very valid point.
    - BenjiWiebe 2y ago
      Ya but they don't get hot when not applied, which means they're not wasting (much) energy.
    - rightbyte 2y ago
      > When you let off the brake pedal, the pressure is removed, but there’s not a “retraction” of any kind. So there’s no pressure but nothing is actually making that gap. The wobble pushes the pads back in, right?
      - smitelli 2y ago
        A healthy disc shouldn’t wobble enough to push much of anything. We’re talking like 1/20th of a millimeter.

robin_reala 2y ago

Yeah, my VE id.3 has drums on the back and disks on the front. Apparently the brake pads are effectively life-of-the-vehicle items under normal driving conditions.

plasticchris 2y ago
I’ve only had to change them one time on any car newer than 1990, after ~200k miles/10 years of use. For most people that qualifies as life of the vehicle, but there was plenty of life left.
- Scoundreller 2y ago
  The drum brakes or the rotors? Certainly not the disk brake pads!
  - plasticchris 2y ago
    Yeah, the pads lasted that long. It was a manual and I did engine break pretty often.
    - plasticchris 2y ago
      * engine brake

m463 2y ago

I suspect drum brakes were chosen by the electron pinching EV engineers. They're the only brakes that are friction-free when not applied. Disc brakes rub (and slow the car) even when not applied.

kstrauser 2y ago
Not significantly. Otherwise they’d get hot and work less well. Pads ride very closely to the disc so that road stuff can’t get wedged between the surfaces, and so that you don’t waste break pedal travel just getting the pads close to the surface. Well adjusted drum brakes should be arranged almost exactly the same way. From https://mechanicswizard.com/how-close-should-brake-pads-be-to-rotors/ https://mechanicswizard.com/how-close-should-brake-pads-be-t...: > Typically, the optimal gap between brake pads and rotors is between 0.5 and 1.5 mm (0.020 to 0.060 inches).
- lukevp 2y ago
  Are you familiar with how disk brakes on a car operate? They’re essentially a hydraulic piston clamping the brake pads against the rotor. When you let off the brake pedal, the pressure is removed, but there’s not a “retraction” of any kind. So there’s no pressure but nothing is actually making that gap. That article was articulating basically that the piston, when not compressing the brake pads, should not be too far out, because that’s just unnecessary travel of the pedal, but it does not mean that the brake pads are somehow gapped away from the rotors. Drum brakes by contrast have springs that retract the pads from the braking surface, so the OP has a very valid point.
  - BenjiWiebe 2y ago
    Ya but they don't get hot when not applied, which means they're not wasting (much) energy.
  - rightbyte 2y ago
    > When you let off the brake pedal, the pressure is removed, but there’s not a “retraction” of any kind. So there’s no pressure but nothing is actually making that gap. The wobble pushes the pads back in, right?
    - smitelli 2y ago
      A healthy disc shouldn’t wobble enough to push much of anything. We’re talking like 1/20th of a millimeter.