5 ms·

>I had the brake fully depressed with around 100kg of force, and the engine was revving to attempt to overcome the brake No, it wasn't. An engine's speed (RPM

>I had the brake fully depressed with around 100kg of force, and the engine was revving to attempt to overcome the brake No, it wasn't. An engine's speed (RPM / "revs") is directly proportional to the drivetrain speed -- the RPMs literally cannot increase unless you are 1) accelerating (actual drivetrain speed going up), 2) shift to a lower gear then slip torque converter to rev match (I assume you're driving automatic), or 3) disengaged from the drivetrain (in neutral gear) and hitting the gas. There's no way for an engine to be "revving" to overcome braking. Hop in a manual car, get up to a normal speed in any gear, then try hitting both the brake and gas.

novaleaf 7y ago
I'm not a car guy, so maybe I am getting some technical terminology wrong. But Toyota's software did cause acceleration even without pushing the accelerator, and even while pressing the brake. They were legally proven to be at fault for that. You can speculate all you want if I was being an idiot and mis-remembering what I personally did, but these facts still stand regardless of my personal experience: 1) Toyota was legally at fault for software caused unintended acceleration in the USA 2) Toyota Thailand never issued a recall for similar makes/years Now maybe the software of cars sold in Thailand is totally different from the software of cars sold in the USA, but the cynic in me thinks it's just that Thailand's lack of consumer protections, plus Toyota's indifference, is the real reason no action was taken.
bagbobillins 7y ago
You are mistaken. In a car with an automatic transmission, the engine RPM is related to the drivetrain speed, but not directly proportional. The input and output shafts of the torque converter always spin at different speeds during acceleration. You can try a similar experiment to the one you proposed in a car with an automatic transmission. Stand firmly on the brake (with the parking brake engaged and nothing in front of the car, for safety), put the car in drive, and give it some gas with your other foot. You can easily get the engine to more than twice the idle speed without the wheels turning at all! (Don't do this for extended periods. It makes the torque converter get hot.)
- parliament32 7y ago
  From a standstill yes -- the car is slipping the torque converter between disengaged (neutral, idle in a standstill) and first (to actually get going). Exactly the same as a manual, to get moving from a standstill you have to slip the clutch somewhat, and yes your RPMs will go up. But that doesn't apply when the car is already in gear and in motion. In both an auto and a manual, if you're applying enough brake to prevent the car from accelerating, the engine will never be "revving" to fight your braking. It will only increase speed if your drivetrain speed increases. I didn't explicitly state it in the above post because I don't want to crap on the parent too much, but the if he was hitting a pedal and the engine was "revving"... he was probably hitting the gas and accelerating.
  - ak217 7y ago
    > he was probably hitting the gas and accelerating. ...Or the car was actuating the throttle as if he was hitting the gas, a.k.a. unintended acceleration. I see a lot of people like you in this thread and elsewhere dismissing unintended acceleration experiences. Before you continue to do so, I would urge you to read the NASA report on the Toyota unintended acceleration case and related documents (https://www.nhtsa.gov/staticfiles/nvs/pdf/NASA-UA_report.pdf https://www.nhtsa.gov/staticfiles/nvs/pdf/NASA-UA_report.pdf, https://users.ece.cmu.edu/~koopman/pubs/koopman14_toyota_ua_slides.pdf https://users.ece.cmu.edu/~koopman/pubs/koopman14_toyota_ua_..., and the link in the top level comment, https://www.edn.com/design/automotive/4423428/Toyota-s-killer-firmware--Bad-design-and-its-consequences https://www.edn.com/design/automotive/4423428/Toyota-s-kille...). It lays out a damning indictment of Toyota's ECU hardware and firmware development culture, that flies directly counter to the happy picture promoted by the "Toyota Way" PR. Toyota never acknowledged the mistakes they made - instead they quietly sacked the head of that division and then most of the staff, and rebuilt it from the ground up. Today's Toyota ECUs appear to be designed quite differently.
    - nihonde 7y ago
      There is a long history of American automakers and their cohorts in the media and elsewhere who use these scandals to scare buyers away from Japanese makes. See what they did to Suzuki with the Jimny in the eighties for the most egregious example. I watched this “scandal” closely at the time, and it smelled like a rat all along. Fortunately, these tactics are ineffective, but there will always be anecdotal persistence on discussion threads like this. Nothing in any credible source materials proved this issue. Settling lawsuits is not an admission of guilt; it’s Japan Inc rolling their eyes, pulling out their pocket books, and making a pragmatic cost/benefit analysis. The lengths to which the case for the unintended acceleration flaw went is proof enough of what their aims were. If you want a counterpoint to the study you cited, here’s one from the National Highway Traffic Safety Administration when American media and automakers pulled the same stunt to slander German makers in the 1980s: https://www.autosafety.org/sites/default/files/1989%20NHTSA%20SA%20Study%20Report%20&%20Appendices%20A-D(1).pdf https://www.autosafety.org/sites/default/files/1989%20NHTSA%...
ak217 7y ago
This is just plain wrong. The poster didn't say they were at a standstill but that they had the brake pedal pressed. That means the engine could have downshifted into 1st gear and started to rev noticeably. The engine would also produce more power (and sound very different) when taking up load, even under the same RPM. Finally, as the other reply pointed out, the engine can spin a clutch or CVT.
- dx034 7y ago
  The poster said that the brake was fully depressed with around 100kg of force. It won't take long for that to be in a standstill. And there's no way acceleration can overpower that kind of brake power. The sound might be scary but it won't change much about brake performance.
  - jacobush 7y ago
    Bad clutch plus bad brakes (but not so bad as to be unserviceable in light, normal use). Story is not implausible.

novaleaf 7y ago

I'm not a car guy, so maybe I am getting some technical terminology wrong. But Toyota's software did cause acceleration even without pushing the accelerator, and even while pressing the brake. They were legally proven to be at fault for that. You can speculate all you want if I was being an idiot and mis-remembering what I personally did, but these facts still stand regardless of my personal experience: 1) Toyota was legally at fault for software caused unintended acceleration in the USA 2) Toyota Thailand never issued a recall for similar makes/years Now maybe the software of cars sold in Thailand is totally different from the software of cars sold in the USA, but the cynic in me thinks it's just that Thailand's lack of consumer protections, plus Toyota's indifference, is the real reason no action was taken.

bagbobillins 7y ago

You are mistaken. In a car with an automatic transmission, the engine RPM is related to the drivetrain speed, but not directly proportional. The input and output shafts of the torque converter always spin at different speeds during acceleration. You can try a similar experiment to the one you proposed in a car with an automatic transmission. Stand firmly on the brake (with the parking brake engaged and nothing in front of the car, for safety), put the car in drive, and give it some gas with your other foot. You can easily get the engine to more than twice the idle speed without the wheels turning at all! (Don't do this for extended periods. It makes the torque converter get hot.)

parliament32 7y ago
From a standstill yes -- the car is slipping the torque converter between disengaged (neutral, idle in a standstill) and first (to actually get going). Exactly the same as a manual, to get moving from a standstill you have to slip the clutch somewhat, and yes your RPMs will go up. But that doesn't apply when the car is already in gear and in motion. In both an auto and a manual, if you're applying enough brake to prevent the car from accelerating, the engine will never be "revving" to fight your braking. It will only increase speed if your drivetrain speed increases. I didn't explicitly state it in the above post because I don't want to crap on the parent too much, but the if he was hitting a pedal and the engine was "revving"... he was probably hitting the gas and accelerating.
- ak217 7y ago
  > he was probably hitting the gas and accelerating. ...Or the car was actuating the throttle as if he was hitting the gas, a.k.a. unintended acceleration. I see a lot of people like you in this thread and elsewhere dismissing unintended acceleration experiences. Before you continue to do so, I would urge you to read the NASA report on the Toyota unintended acceleration case and related documents (https://www.nhtsa.gov/staticfiles/nvs/pdf/NASA-UA_report.pdf https://www.nhtsa.gov/staticfiles/nvs/pdf/NASA-UA_report.pdf, https://users.ece.cmu.edu/~koopman/pubs/koopman14_toyota_ua_slides.pdf https://users.ece.cmu.edu/~koopman/pubs/koopman14_toyota_ua_..., and the link in the top level comment, https://www.edn.com/design/automotive/4423428/Toyota-s-killer-firmware--Bad-design-and-its-consequences https://www.edn.com/design/automotive/4423428/Toyota-s-kille...). It lays out a damning indictment of Toyota's ECU hardware and firmware development culture, that flies directly counter to the happy picture promoted by the "Toyota Way" PR. Toyota never acknowledged the mistakes they made - instead they quietly sacked the head of that division and then most of the staff, and rebuilt it from the ground up. Today's Toyota ECUs appear to be designed quite differently.
  - nihonde 7y ago
    There is a long history of American automakers and their cohorts in the media and elsewhere who use these scandals to scare buyers away from Japanese makes. See what they did to Suzuki with the Jimny in the eighties for the most egregious example. I watched this “scandal” closely at the time, and it smelled like a rat all along. Fortunately, these tactics are ineffective, but there will always be anecdotal persistence on discussion threads like this. Nothing in any credible source materials proved this issue. Settling lawsuits is not an admission of guilt; it’s Japan Inc rolling their eyes, pulling out their pocket books, and making a pragmatic cost/benefit analysis. The lengths to which the case for the unintended acceleration flaw went is proof enough of what their aims were. If you want a counterpoint to the study you cited, here’s one from the National Highway Traffic Safety Administration when American media and automakers pulled the same stunt to slander German makers in the 1980s: https://www.autosafety.org/sites/default/files/1989%20NHTSA%20SA%20Study%20Report%20&%20Appendices%20A-D(1).pdf https://www.autosafety.org/sites/default/files/1989%20NHTSA%...

ak217 7y ago

This is just plain wrong. The poster didn't say they were at a standstill but that they had the brake pedal pressed. That means the engine could have downshifted into 1st gear and started to rev noticeably. The engine would also produce more power (and sound very different) when taking up load, even under the same RPM. Finally, as the other reply pointed out, the engine can spin a clutch or CVT.

dx034 7y ago
The poster said that the brake was fully depressed with around 100kg of force. It won't take long for that to be in a standstill. And there's no way acceleration can overpower that kind of brake power. The sound might be scary but it won't change much about brake performance.
- jacobush 7y ago
  Bad clutch plus bad brakes (but not so bad as to be unserviceable in light, normal use). Story is not implausible.