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イリジウム
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11,866 Posts
With older transmissions like the A series the converter clutch doesn’t lock until higher speeds. With newer transmissions and partial lock converters I don’t know how each manufacturer handles it.

With the German ZFs I believe they go neutral to save gas and wear and tear.

I didn’t used to shift into neutral but do now.


I almost always shift to neutral when I'm waiting on a traffic light. It bothers me to feel the engine and transmission pulling against the brakes. I think shifting to neutral saves a little gas and possibly saves some wear on the transmission. I don't know if the clutch plates are physically in contact or if it's just friction of trans fluid in a small gap between separated clutch plates but it seems to me that if there is enough friction when in D on a slight incline and the car doesn't roll back, then there must be some wear occurring. I want to hear if someone who really knows, not just guessing, that no significant wear occurs when in D with brake applied to keep from rolling forward. There is some kind of part that probably gets additional wear by me frequently shifting from neutral to drive but it's still in good shape at over a half-million miles.
 

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Token Aussie
1998 AE102, 2018 ZRE182
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1,833 Posts
You are correct: with an AT, holding the car still with the brakes, while in D, doesn't create any wear, it is just fluid pumping (there aren't any clutch discs in contact in that situation).

Putting it into N disconnects the input and stops pumping the fluid, and the engine can relax ( = less vibration while waiting for the light).

x2 the shifter durability, no concerns there either.
^this, the torque converter is a fluid coupling, essentially a "liquid clutch" so all the slipping occurs there
 

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Registered
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50 Posts
Interesting. I used to shift into neutral at stop lights, but was then told not to.


RAY: For our other readers who may be curious, you should not shift out of "drive" when stopped at a light. That does not spare the transmission excess wear and tear. On the contrary, every time you shift from "park" or "neutral" into "drive," you jolt all the moving parts of the drive train. The engine couldn't care less, but the transmission, the differential, and the CV joints will suffer.
TOM: If, on the other hand, you're stopped for more than five minutes or so, then you can put it in "park." That's called parking. When you do that, you might also consider turning off the engine and going for a slice of pizza.


I guess it doesn't really matter either way. But I'd just turn it off waiting for a train.

 

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Premium Member
1993 Camry SE,V6-5MT
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428 Posts
it is hilarious that the link said not to shift into neutral because it caused wear and tear to do so, but then recommended shifting into park instead, which is exactly the same thing as far as the transmission is concerned (except for the park "dog" engaging in its slot), the shifter and the rest of the car
 

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MR2 3.3TT
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198 Posts
It caused exactly zero accidents, no mechanical or electrical fault was ever found.
But software faults were found. Not sure it's every been proven, but during the investigation multiple software issues were discovered that may have led to the accidents.

http://www.safetyresearch.net/Library/Koopman 10-11-13 a.m.PDF
http://www.safetyresearch.net/Library/Koopman 10-11-13 p.m.pdf
http://www.safetyresearch.net/Library/Bookout_v_Toyota_Barr_REDACTED.pdf
http://www.safetyresearch.net/Library/BarrSlides_FINAL_SCRUBBED.pdf

Are you sure all 3rd and 4th gens have a rev limiter? My 99 1mzfe did not hit one in neutral at 5k. Is it higher than that?
Yes, about 6300
 

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Premium Member
1993 Camry SE,V6-5MT
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428 Posts
"It caused exactly zero accidents, no mechanical or electrical fault was ever found." is the same as I remember NASA and the other disinterested 3rd party software and system analysis results said.
Of course, at the local level, lawyers will try to use whatever they can lay their hands on, so I'm not surprised that transcripts from trials would include suggestions and questions, like those linked above. That's different, though, from proving a thing.
 

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MR2 3.3TT
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198 Posts
That's different, though, from proving a thing.
Right. Hard to prove such a random event one way or another, but the vulnerability is clear. Don't get me wrong I love my Toyotas, but the software has issues - maybe it has caused problems maybe not. ECC RAM exists for a reason...

Toyota has also issued recalls for UA, a huge one for gas pedals physically stuck under floor mats and another one to make the computer go to idle when the brake is applied. There were also a few other related recalls.
 

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500,000 + Miles
2000 Solara
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432 Posts
That bump as you go from N to D is the part I wonder if I may do more harm than good. I have been doing it now for 5-10 years, since gas prices were so high I was thinking more about burning gas while my engine was pulling against the brakes. We only burn a tiny bit of gas at idle but I didn't have anything better to do with my time so I began shifting to N at lights. I would worry more about the re-engage bump if the idle were set high or when it's normally higher anyway like when the AC is on or when the car is still warming up.

On the car runaway topic, I was always skeptical of those. Aside from applying the brakes, including the emergency brakes, there are two other, mechanically unrelated, ways to remove the power from the engine of it were revving up....turn off the key...and that can be done only to ACC so you don't lock the steering....and you can put the car in P or N....or even one of the lower gears. You may destroy the transmission or the engine but the car wouldn't keep gaining speed. Those stories just never did make sense to me. As newer cars are made with fewer mechanical linkages from the driver to the engine and computers are handling steering, braking, throttle, transmission, and probably lots of other things, then we have more possibilities for computer glitches causing accidents. I REALLY don't want a computer to be between the driver and the steering, braking, or the throttle.
 

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MR2 3.3TT
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198 Posts
and that can be done only to ACC so you don't lock the steering
FYI on a modern Toyota it shouldn't lock until you actually pull the key out. If you switch it off but leave the key in the steering column should stay unlocked. Still safer to go for ACC, but nice to know you have that added safety feature.
 

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Premium Member
1993 Camry SE,V6-5MT
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428 Posts
veering even further off the original topic, into unintended acceleration discussion: the challenge is what do you do in a panic situation? The fact is that most people, who know what to do and are level headed, when confronted with a truly panic situation will react first and think later, that's human nature. If the result was a foot planted on the accelerator, the brain will fill in the gaps with an unshakable belief that it was, in fact, on the brake the whole time. Modern vehicles with data play back show that this is the case in most instances.

As far as putting the key into ACC, or the shifter into N, those work when those things work in a familiar manner. Unfortunately, in a car not equipped with an ignition key cylinder, not all folks knew that it was necessary to hold the "Start" button down for several seconds to override/engine shut down. Today, all OEMs use a panic "multiple quick presses" as an emergency input and that action will now also engage engine shut down. That mode wasn't available when the first push button cars were produced.

Same thing for putting it into N. With the advent of AT4 and AT5 (up to AT10 now) transmissions, it was no longer possible to put all gear positions into a straight line, so the "zig-zag" pattern was developed (first in Germany, then all OEMs began to adopt it). The driver of the car that famously crashed was an experienced LAPD officer who was used to Ford Crown Vic "PRNDL" shift pattern. I suspect that he, of course, tried to get it into N, but perhaps lack of familiarity + panic didn't. The root cause was a stuck floor mat, but those other things could have contributed.

The whole industry uses a process called ISO26262 to analyze software and electronics to verify there is no way they can fail in a manner that will allow an unsafe outcome. It is used to prove, up front, what took several years to prove after the fact, that the software was not possible of failing in a manner which could cause the incident. Instead, the casuses were all mechanical and human factor issues.
 

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イリジウム
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11,866 Posts
At warm idle the shifting bump probably isn’t a big deal. I don’t know, but I think I’ll keep going into neutral.

Yeah even my iPhone has a lot of software bugs. My guess is either that or a lack of redundancy (single pedal position sensor within the assembly?) was the reason behind the sudden acceleration deaths. I know the new pedals have 2 sensors that check against each other, not sure about old ones. Kinda like the 737Max thing. Real sad.

That bump as you go from N to D is the part I wonder if I may do more harm than good. I have been doing it now for 5-10 years, since gas prices were so high I was thinking more about burning gas while my engine was pulling against the brakes. We only burn a tiny bit of gas at idle but I didn't have anything better to do with my time so I began shifting to N at lights. I would worry more about the re-engage bump if the idle were set high or when it's normally higher anyway like when the AC is on or when the car is still warming up.

On the car runaway topic, I was always skeptical of those. Aside from applying the brakes, including the emergency brakes, there are two other, mechanically unrelated, ways to remove the power from the engine of it were revving up....turn off the key...and that can be done only to ACC so you don't lock the steering....and you can put the car in P or N....or even one of the lower gears. You may destroy the transmission or the engine but the car wouldn't keep gaining speed. Those stories just never did make sense to me. As newer cars are made with fewer mechanical linkages from the driver to the engine and computers are handling steering, braking, throttle, transmission, and probably lots of other things, then we have more possibilities for computer glitches causing accidents. I REALLY don't want a computer to be between the driver and the steering, braking, or the throttle.
 

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イリジウム
Joined
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11,866 Posts
The thing is, if the sensor failed and says you’re at full throttle, what does the computer record? What did the computer think in the two Max cases? You’ll need a video recording to tell for sure.

As far as straight travel shifter design yeah I think Toyota sucks. So people practice shifting into neutral at the light. Might save your life one day. ;)

veering even further off the original topic, into unintended acceleration discussion: the challenge is what do you do in a panic situation? The fact is that most people, who know what to do and are level headed, when confronted with a truly panic situation will react first and think later, that's human nature. If the result was a foot planted on the accelerator, the brain will fill in the gaps with an unshakable belief that it was, in fact, on the brake the whole time. Modern vehicles with data play back show that this is the case in most instances.

As far as putting the key into ACC, or the shifter into N, those work when those things work in a familiar manner. Unfortunately, in a car not equipped with an ignition key cylinder, not all folks knew that it was necessary to hold the "Start" button down for several seconds to override/engine shut down. Today, all OEMs use a panic "multiple quick presses" as an emergency input and that action will now also engage engine shut down. That mode wasn't available when the first push button cars were produced.

Same thing for putting it into N. With the advent of AT4 and AT5 (up to AT10 now) transmissions, it was no longer possible to put all gear positions into a straight line, so the "zig-zag" pattern was developed (first in Germany, then all OEMs began to adopt it). The driver of the car that famously crashed was an experienced LAPD officer who was used to Ford Crown Vic "PRNDL" shift pattern. I suspect that he, of course, tried to get it into N, but perhaps lack of familiarity + panic didn't. The root cause was a stuck floor mat, but those other things could have contributed.

The whole industry uses a process called ISO26262 to analyze software and electronics to verify there is no way they can fail in a manner that will allow an unsafe outcome. It is used to prove, up front, what took several years to prove after the fact, that the software was not possible of failing in a manner which could cause the incident. Instead, the casuses were all mechanical and human factor issues.
 
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