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For the brakes to seize from rust you'd really need to have not used them for quite a while. I have a Model 3 and a Subaru STI (disc brakes on all four wheels)

For the brakes to seize from rust you'd really need to have not used them for quite a while. I have a Model 3 and a Subaru STI (disc brakes on all four wheels). I usually use regen in the Model 3, but not as much in the winter (it's disabled below certain temps). The brakes work fine even after exclusive regen use for months. The STI rarely gets driven. It'll go 3-4 months of not going anywhere and frequently gets a layer of surface rust on the discs as a result. 10 minutes of driving and the rust is gone. This is a track car as well, and before it's driven it gets a safety inspection as required by the track owners. It's never failed because of surface rust on the discs. For disc brakes to rust to the point of failure would require some serious neglect in addition to harsh conditions. At that point, rusted discs are probably the least of your concerns, as the rest of the car is likely a pile of red dust.

TheLoafOfBread 4y ago
> For disc brakes to rust to the point of failure would require some serious neglect in addition to harsh conditions. At that point, rusted discs are probably the least of your concerns, as the rest of the car is likely a pile of red dust. Actually it was kind of normal for Toyota Prius to have seized brakes because they weren't used thanks to regen.
- buffington 4y ago
  No, that is not normal. Regen doesn't completely turn off your traditional braking system in a Prius. My wife has driven the same Prius for the past 12 years and if that model of car was prone to having its most important safety system seize up, there'd have been a massive recall for that specific issue. I've replaced the brake pads twice myself in those 12 years, and have had a mechanic do it once. The wear and tear have looked like any other old brake pad I've replaced in other cars. The discs have never looked worn beyond what's normal for a 12 year old car. Looking through my records turned up a single brake related recall specific to our model year, except it was for the parking brake. The issue they were fixing could occur if: "the driver exits the vehicle with the transmission in a gear other than ‘Park’ while the ignition is on," and required having a tiny clip installed. There was another brake related recall that was more severe, but didn't impact our model year. It did however apply to other model year Prius', and several other Toyota/Lexus models, most of which are traditional ICE vehicles without regenerative braking. Nothing to do with brakes seizing. Also, rusty rotors wouldn't cause brake calipers to seize. That'd be an issue with the calipers themselves. I'll concede that having brake pads degrade or fail could contribute to calipers seizing, and that a severely rusted disc could contribute to pad failure, but that's still a long shot. Again, the disc would have to be so severely rusted that it'd damage the pads. You'd be more at risk of pad damage from road grit than you would from the typical surface rust one gets from not using the vehicle at all.
  - TheLoafOfBread 4y ago
    It is absolutely normal. Main reason why VW ID.3 has drum brakes instead of disc brakes.
    - buffington 4y ago
      Wrong on two counts. The minor one: a VW ID.3 also has disc brakes. The major reason you're wrong is that the very manufacturer of the braking system, ZF Friedrichshafen AG, has described exactly why they decided to design and develop an entirely new type of drum brake system instead of using proven technology like disc brakes. Here's what Manfred Meyer, Senior VP of ZF's Safety division said about them: > The braking system for a battery-electric vehicle utilizes intelligent integration in a number of ways. For example, we can eliminate the need for a mechanical locking mechanism in the drivetrain and keep the vehicle in park mode through software that controls this function within the ESC and redundantly in the Electronic Brake Booster unit. The brake system itself helps ensure that the car cannot move – this saves cost and results in less weight. This system also allows for automatic stability control and advanced driver assist features that require automatic emergency braking. You'd think if rusty rotors and seizing calipers were what motivated them to use technology that's almost universally seen as inferior, people like Manfred would be quick to defend their choice by pointing out the obvious flaw with disc brakes and regen, as you've been so enthusiastically doing. Not sure it matters much to you though. If I were Manfred Meyer himself and I explained in great detail why you're wrong, you'd probably still insist on maintaining your ignorance so you could win some sort of HN contest. To save us both some time: you win. You're right. The VW ID.3 has drum brakes in the rear, and disc brakes in the front, because "regen seizes brakes," and we have you to thank for setting the record straight.

TheLoafOfBread 4y ago

> For disc brakes to rust to the point of failure would require some serious neglect in addition to harsh conditions. At that point, rusted discs are probably the least of your concerns, as the rest of the car is likely a pile of red dust. Actually it was kind of normal for Toyota Prius to have seized brakes because they weren't used thanks to regen.

buffington 4y ago
No, that is not normal. Regen doesn't completely turn off your traditional braking system in a Prius. My wife has driven the same Prius for the past 12 years and if that model of car was prone to having its most important safety system seize up, there'd have been a massive recall for that specific issue. I've replaced the brake pads twice myself in those 12 years, and have had a mechanic do it once. The wear and tear have looked like any other old brake pad I've replaced in other cars. The discs have never looked worn beyond what's normal for a 12 year old car. Looking through my records turned up a single brake related recall specific to our model year, except it was for the parking brake. The issue they were fixing could occur if: "the driver exits the vehicle with the transmission in a gear other than ‘Park’ while the ignition is on," and required having a tiny clip installed. There was another brake related recall that was more severe, but didn't impact our model year. It did however apply to other model year Prius', and several other Toyota/Lexus models, most of which are traditional ICE vehicles without regenerative braking. Nothing to do with brakes seizing. Also, rusty rotors wouldn't cause brake calipers to seize. That'd be an issue with the calipers themselves. I'll concede that having brake pads degrade or fail could contribute to calipers seizing, and that a severely rusted disc could contribute to pad failure, but that's still a long shot. Again, the disc would have to be so severely rusted that it'd damage the pads. You'd be more at risk of pad damage from road grit than you would from the typical surface rust one gets from not using the vehicle at all.
- TheLoafOfBread 4y ago
  It is absolutely normal. Main reason why VW ID.3 has drum brakes instead of disc brakes.
  - buffington 4y ago
    Wrong on two counts. The minor one: a VW ID.3 also has disc brakes. The major reason you're wrong is that the very manufacturer of the braking system, ZF Friedrichshafen AG, has described exactly why they decided to design and develop an entirely new type of drum brake system instead of using proven technology like disc brakes. Here's what Manfred Meyer, Senior VP of ZF's Safety division said about them: > The braking system for a battery-electric vehicle utilizes intelligent integration in a number of ways. For example, we can eliminate the need for a mechanical locking mechanism in the drivetrain and keep the vehicle in park mode through software that controls this function within the ESC and redundantly in the Electronic Brake Booster unit. The brake system itself helps ensure that the car cannot move – this saves cost and results in less weight. This system also allows for automatic stability control and advanced driver assist features that require automatic emergency braking. You'd think if rusty rotors and seizing calipers were what motivated them to use technology that's almost universally seen as inferior, people like Manfred would be quick to defend their choice by pointing out the obvious flaw with disc brakes and regen, as you've been so enthusiastically doing. Not sure it matters much to you though. If I were Manfred Meyer himself and I explained in great detail why you're wrong, you'd probably still insist on maintaining your ignorance so you could win some sort of HN contest. To save us both some time: you win. You're right. The VW ID.3 has drum brakes in the rear, and disc brakes in the front, because "regen seizes brakes," and we have you to thank for setting the record straight.