Automatic gearbox and regular use of neutral

Herzlos

BOWFER said:

Mark_in_Kent said:

itsmeagain said:

To quote the highway code is ridiculous and out dated. If you followed that you'd claim Lewis Hamilton is the worlds worst driver!

The highway code is for the road, not racing tracks. Daft comment.

 The Highway Code is still valid, we take our tests against it. 

Parts of it are still valid, parts of it are a joke.
Braking distances especially, utter nonsense that are easily halved by even a run-of-the-mill car.

True, but take a poorly maintained older run-of-the-mill care that's borderline overloaded. The HC is a worst case and if you brake according to that you should be fine with a decent car (unless someone runs into the back of you because you stopped too quickly).

ontheroad1970

itsmeagain said:

ontheroad1970 said:

I don't see how locking the wheels is a desirable thing at all, what with ABS and all.

Just to clarify, no one said that it was desirable to lock-up the wheels. I was saying that "modern braking systems are perfectly capable of locking the wheels". I.e, modern brakes are more than capable of achieving maximum braking, without the additional support of engine braking to do so.

The question... why would additional 'in gear' engine braking make the car stop quicker than using a modern braking system alone? I.e, "with ABS and all"

You think it will be safer with switched off engines?  You seem to be all for them.  So all electrics disengaged, an extra step to take to react to an unpredictable incident, or a predictable incident with an inattentive driver.  Of course those that want to lessen the safety protections are always 100% safe and attentive with eyes all over their heads so they never miss a thing.  

Back in the real world, all drivers get inattentive from time to time, some more than others.  Id rather that other drivers weren't turning their ignition off, with less power being supplied to the bakes through servo systems etc.  

The reference to locking brakes being desirable was inferred by your comment try comprehending what you write.

Herzlos

itsmeagain said:

Can you please explain why you think that a modern auto vehicle, auto selecting the highest gear and only changing down each time the revs get low (offering very low engine braking), would stop significantly earlier, than the same vehicle in Neutral. Bear in mind that modern braking systems are perfectly capable of locking the wheels and delivering near perfect cadence braking whether in gear or not?

Presumably said modern auto would start changing down gear quickly when the brakes are pressed hard and the vehicle speed reduces, thus increasing the effect of engine braking? Even if it's only a slight effect in higher gears, more braking is better than none in an emergency situation?

Plus there's no guarantee that the brakes are actually cold, if the driver has been riding them all the way down the hill to try and maintain a steady speed.

BOWFER

Herzlos said:

itsmeagain said:

Can you please explain why you think that a modern auto vehicle, auto selecting the highest gear and only changing down each time the revs get low (offering very low engine braking), would stop significantly earlier, than the same vehicle in Neutral. Bear in mind that modern braking systems are perfectly capable of locking the wheels and delivering near perfect cadence braking whether in gear or not?

Presumably said modern auto would start changing down gear quickly when the brakes are pressed hard and the vehicle speed reduces, thus increasing the effect of engine braking? Even if it's only a slight effect in higher gears, more braking is better than none in an emergency situation?

Plus there's no guarantee that the brakes are actually cold, if the driver has been riding them all the way down the hill to try and maintain a steady speed.

If the brakes are already at maximum and the ABS is kicking in, any arguable engine braking effect isn't going to add anything to the equation.
These gearboxes don't change down that quickly anyway, they don't pop down the gears like an F1 car.

Advocado

Herzlos said:

itsmeagain said:

Can you please explain why you think that a modern auto vehicle, auto selecting the highest gear and only changing down each time the revs get low (offering very low engine braking), would stop significantly earlier, than the same vehicle in Neutral. Bear in mind that modern braking systems are perfectly capable of locking the wheels and delivering near perfect cadence braking whether in gear or not?

Presumably said modern auto would start changing down gear quickly when the brakes are pressed hard and the vehicle speed reduces, thus increasing the effect of engine braking? Even if it's only a slight effect in higher gears, more braking is better than none in an emergency situation?

Plus there's no guarantee that the brakes are actually cold, if the driver has been riding them all the way down the hill to try and maintain a steady speed.

I don’t know anything mechanical, but I’d assume an automatic car actually disengages the engine under hard braking.  Makes sense to me that you wouldn’t want the added inertia of the engine when trying to brake that hard.

I haven’t driven a manual for many years, but aren’t you supposed to depress the clutch and brake when emergency braking?

Cash-Strapped.T32

Iirc clutch in when emergency braking is because in an emergency you're unlikely to be in a position/have time to consider chucking the car into neutral and you don't want to come to a halt inches away from a hazard only for the car to lurch forward at the last, due to being left in gear... At least that's what my old instructor told me me, no idea if that's 100% accurate or not..

Fascinating thread btw

fred990

shinytop said:

itsmeagain said:

Jenni_D said:

Does the OP "blip" the throttle when switching back to D? (Same as you'd do in a manual if dropping down gears to e.g. make an overtake - you'd blip the throttle to align the revs to the trans speed).

You may be surprised that flight recorders show that less than 10% of people do this. Also only 18% of people proactively blend off the brake when stopping (to stop the vehicle jerk)! Maybe it doesn't tell you to do it in the highway code.

but nearly all of them are over 65, wear driving gloves and read the highway code a lot. 

And wear a hat when driving.....

Jenni_D

ontheroad1970 said:

itsmeagain said:

ontheroad1970 said:

I don't see how locking the wheels is a desirable thing at all, what with ABS and all.

Just to clarify, no one said that it was desirable to lock-up the wheels. I was saying that "modern braking systems are perfectly capable of locking the wheels". I.e, modern brakes are more than capable of achieving maximum braking, without the additional support of engine braking to do so.

The question... why would additional 'in gear' engine braking make the car stop quicker than using a modern braking system alone? I.e, "with ABS and all"

You think it will be safer with switched off engines?  You seem to be all for them.  So all electrics disengaged, an extra step to take to react to an unpredictable incident, or a predictable incident with an inattentive driver.  Of course those that want to lessen the safety protections are always 100% safe and attentive with eyes all over their heads so they never miss a thing.  

Back in the real world, all drivers get inattentive from time to time, some more than others.  Id rather that other drivers weren't turning their ignition off, with less power being supplied to the bakes through servo systems etc.  

The reference to locking brakes being desirable was inferred by your comment try comprehending what you write.

Bit in bold could be reverted back at you (somewhat) - try comprehending what you read. (The poster you've quoted has not advocated doing the bit in underline).  

Ditzy_Mitzy

Herzlos said:

itsmeagain said:

Can you please explain why you think that a modern auto vehicle, auto selecting the highest gear and only changing down each time the revs get low (offering very low engine braking), would stop significantly earlier, than the same vehicle in Neutral. Bear in mind that modern braking systems are perfectly capable of locking the wheels and delivering near perfect cadence braking whether in gear or not?

Presumably said modern auto would start changing down gear quickly when the brakes are pressed hard and the vehicle speed reduces, thus increasing the effect of engine braking? Even if it's only a slight effect in higher gears, more braking is better than none in an emergency situation?

Plus there's no guarantee that the brakes are actually cold, if the driver has been riding them all the way down the hill to try and maintain a steady speed.

It depends what type of auto it is.  If conventional and changing down, it will need to unlatch the torque convertor.  In such a state the engine braking effect will be negligible as there is no solid link between the engine and the wheels.  Automated manual is anyone's guess, and will depend on whether the car lets the clutch in between down changes.  I'd assume not, as it may want to avoid damaging anything.  

ontheroad1970

Jenni_D said:

ontheroad1970 said:

itsmeagain said:

ontheroad1970 said:

I don't see how locking the wheels is a desirable thing at all, what with ABS and all.

Just to clarify, no one said that it was desirable to lock-up the wheels. I was saying that "modern braking systems are perfectly capable of locking the wheels". I.e, modern brakes are more than capable of achieving maximum braking, without the additional support of engine braking to do so.

The question... why would additional 'in gear' engine braking make the car stop quicker than using a modern braking system alone? I.e, "with ABS and all"

You think it will be safer with switched off engines?  You seem to be all for them.  So all electrics disengaged, an extra step to take to react to an unpredictable incident, or a predictable incident with an inattentive driver.  Of course those that want to lessen the safety protections are always 100% safe and attentive with eyes all over their heads so they never miss a thing.  

Back in the real world, all drivers get inattentive from time to time, some more than others.  Id rather that other drivers weren't turning their ignition off, with less power being supplied to the bakes through servo systems etc.  

The reference to locking brakes being desirable was inferred by your comment try comprehending what you write.

Bit in bold could be reverted back at you (somewhat) - try comprehending what you read. (The poster you've quoted has not advocated doing the bit in underline).  

I'm quite capable of admitting when I am wrong.  If you read through my posts and you'll see a smattering of them.  

There was talk earlier in the thread by that poster about being able to turn off the engine while coasting - if you read further up my post, you will see it in the context in which I wrote it - The first sentence is a question, not a statement of what I think his views are.  

My point is that if I am driving uphill on a twisty road (there are many close to me in Wales) and the driver is coming down and is having a discussion with his passenger or chastising his children in the back, and so therefore hasn't seen the sheep that is about to step into the road, I'd rather he had ALL  available tools at his disposal, not half of them non functioning because the ignition is off or is coasting.  Sometimes it is just in the nick of time that a collision is avoided.