tu204
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Question About Using Neutral In Automatic Car

Sun Nov 26, 2006 12:33 pm

I recently bought a 1999 BMW 740iL with an automatic transmission. My second car is that nice classic 1970 Volga 21 which has a standard transmission. I am very used to making use of "neutral" when driving to maximise economy (I don't like coasting down a small hill or to a stop sign in speed so I put it into neutral and that is usually enough to maintain speed when on a slope or slowly reduce speed if coasting towards a red light...hey, it beats speeding towards a light and them slamming your brakes on)
So anyways, my question: Is it ok to put an automatic car into neutral when coasting down a hill or going towards a light? Is there any negative effect on the transmission itself?
Any opinions would be appreaciated!
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Go3Team
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RE: Question About Using Neutral In Automatic Car

Sun Nov 26, 2006 12:50 pm

Using neutral in a standard transmission can cause damage to the transmission using it as you described. You are not saving much, if any fuel by doing so. There isn't any reason to do so in an automatic as well. The transmission does all of the work for you. You also risk the possibility of accidently putting it in reverse while moving forward. That can be bad. Doing what you are doing could also impact your concentration on driving.
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Jamie757
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RE: Question About Using Neutral In Automatic Car

Sun Nov 26, 2006 12:58 pm

Quoting Tu204 (Thread starter):

You'd probably get better fuel consumption if you used the selector positions 1, 2, 3 (assuming it's a fairly steep hill). No doubt you'd have more control over the vehicle too.

Also, the speed at which you can travel in some automatics (whilst in neutral), is recommended to be kept below 50mph or so to avoid damage to the transmission.

False economy if you ask me!

Rgds.

[Edited 2006-11-26 05:04:14]
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Boston92
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RE: Question About Using Neutral In Automatic Car

Sun Nov 26, 2006 12:58 pm

My brother puts his automatic in neutral going down a pass (or long grade), for about 15-20 minutes. It might not be very good, but just remember, never rev the engine.
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Shawn Patrick
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RE: Question About Using Neutral In Automatic Car

Sun Nov 26, 2006 1:02 pm

So is this why I had to get a new transmission?  banghead 

Why exactly is it bad for it?
 
ArmitageShanks
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RE: Question About Using Neutral In Automatic Car

Sun Nov 26, 2006 1:04 pm

Quoting Boston92 (Reply 3):
It might not be very good, but just remember, never rev the engine.

Why not rev the engine?
 
Boston92
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RE: Question About Using Neutral In Automatic Car

Sun Nov 26, 2006 1:07 pm

Quoting ArmitageShanks (Reply 5):
Why not rev the engine?

When going 70 down a hill, in neutral, and you rev the engine, it gets up to 5 or 6 thousand RPM, and you risk blowing your engine.
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JAGflyer
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RE: Question About Using Neutral In Automatic Car

Sun Nov 26, 2006 1:12 pm

Never used neutral except when going through a car wash or when parking on a slight incline to move my car a bit away from the curb. The shifter will not go beyong N from D unless you push the button in.
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Jamie757
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RE: Question About Using Neutral In Automatic Car

Sun Nov 26, 2006 1:23 pm

Quoting Shawn Patrick (Reply 4):
Why exactly is it bad for it?

It overheats the torque converter. Also, on some vehicles the engine oil lubricates the transmission, high vehicle speed + low engine speed = damaged transmission.

On most modern vehicles with manual transmission, the engine management system cuts fuel delivery almost completely when you ease off the accelerator (providing that you are in a gear and the clutch is up), if you are in neutral, then the engine reverts to idle speed instead. That uses fuel.

Rgds.
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tu204
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RE: Question About Using Neutral In Automatic Car

Sun Nov 26, 2006 1:36 pm

Quoting Go3Team (Reply 1):
You also risk the possibility of accidently putting it in reverse while moving forward.

I don't know about other cars, but in my BMW it does blocks R unless you are standing still. It simply wont engage Reverse if you are moving quickly.
On my standard Volga it is nearly impossible do this either because of the mechanics of it (the gears just won't click in). I actually had this happen inadvertainly when I just bought the Volga because of the strange way they arranged the speeds.(idiotic-the lever is on the steering column and the arrangement is an upside down "tree" that most cars usually have-takes a while to get used to) I kept trying to put it into Reverse instead of 3rd gear and it never did it (it would just "grind" for a second untill I realised my mistake). I did however manage to put it into Reverse instead of 1st gear several times when at a parking lot or a traffic light (freaked out the people behind me I think!), but that is from a standstill, and again because of the arrangement of the speeds and my incompetence.
In the standard transmission using neutral only causes damage if you improperly re-engage it (i.e. the engine's RPM is much lower than that of the transmission and when you put it back into gear it will slow down with a jolt.) But all I do is give it a little gas (depending on the speed I am going) and then put it in making a smooth transition. I assume the damage you are referring to in an automatic is for the same reason?

Quoting Boston92 (Reply 6):
When going 70 down a hill, in neutral, and you rev the engine, it gets up to 5 or 6 thousand RPM, and you risk blowing your engine.

 checkmark 

Quoting Go3Team (Reply 1):
Doing what you are doing could also impact your concentration on driving.

Definatly. Agree with you 100%. But I am used to driving standard and that takes a bit more concentration if you ask me.

Quoting JAGflyer (Reply 7):
The shifter will not go beyong N from D unless you push the button in.

Really? What car do you have? My BMW and all standards that I have ever driven (modern ones) require you to simply push the level from N to D to 3 to 2 to 1. You only press the button when going into R, P from P or P from N I think.
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Klaus
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RE: Question About Using Neutral In Automatic Car

Sun Nov 26, 2006 1:40 pm

Quoting Jamie757 (Reply 8):
On most modern vehicles with manual transmission, the engine management system cuts fuel delivery almost completely when you ease off the accelerator (providing that you are in a gear and the clutch is up), if you are in neutral, then the engine reverts to idle speed instead. That uses fuel.

I think that's a fallacy. If you don't switch to neutral when going downhill with a manual and the motor management cuts off all fuel to the engine, the engine will act as a brake - if the hill is not steep enough to warrant that amount of braking, you'd have to push a bit on the accelerator anyway just to maintain the engine turning at the speed corresponding to your current speed. And that will very likely require more fuel than it would in idle.

I'd expect that you'd only save any fuel if you were going slower than with the engine at idle, and that is very, very rare.

I still see no good reason to not use neutral for fuel saving with a manual gearbox.

By the way: I'd prefer to have the relatively cheap brake pads replaced instead of the motor after being abused as a brake.
 
Go3Team
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RE: Question About Using Neutral In Automatic Car

Sun Nov 26, 2006 2:01 pm

Quoting Klaus (Reply 10):
I think that's a fallacy. If you don't switch to neutral when going downhill with a manual and the motor management cuts off all fuel to the engine, the engine will act as a brake

That's kind of the point.

Quoting Klaus (Reply 10):
By the way: I'd prefer to have the relatively cheap brake pads replaced instead of the motor after being abused as a brake.

You cause more abuse by starting your engine than using it as a brake. Using the engine for compression braking in no way harms the engine. The fuel saved probably wouldn't even cover the costs of the brake pads.
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ArmitageShanks
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RE: Question About Using Neutral In Automatic Car

Sun Nov 26, 2006 2:12 pm

Quoting Boston92 (Reply 6):
When going 70 down a hill, in neutral, and you rev the engine, it gets up to 5 or 6 thousand RPM, and you risk blowing your engine.

Wow, I didn't know it would do something like that. What causes it to do that at a high speed compared with doing it at idle?
 
GQfluffy
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RE: Question About Using Neutral In Automatic Car

Sun Nov 26, 2006 2:24 pm

Quoting Boston92 (Reply 6):
it gets up to 5 or 6 thousand RPM

If a engine in any of my vehicles blows while reving to 5 or 6 thousand RPM, then I would think that engine is a pice of shat. If I can't rev it to red line...(assuming I'm not bouncing it off the rev-limiter) from time to time...whether reving it or racing to redline...then IMNSHO it was a crappy motor from the get-go.
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Jamie757
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RE: Question About Using Neutral In Automatic Car

Sun Nov 26, 2006 2:25 pm

Quoting Klaus (Reply 10):
I still see no good reason to not use neutral for fuel saving with a manual gearbox.

I do, it gives me/you a lot more control whilst slowing the vehicle down. Think of it like this, if the engine is braking as well, then you effectively have two brakes working for you. This means less wear on your brake pads. As said by Go3Team previously, it doesn't do the engine any harm (or abuse as you put it).

 Smile

Rgds.
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cfalk
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RE: Question About Using Neutral In Automatic Car

Sun Nov 26, 2006 2:29 pm

Quoting Go3Team (Reply 1):
Using neutral in a standard transmission can cause damage to the transmission using it as you described.

That's the way they were designed to be used. How can you damage it?The gears are simply spinning without being meshed.

Quoting Klaus (Reply 10):
I think that's a fallacy. If you don't switch to neutral when going downhill with a manual and the motor management cuts off all fuel to the engine, the engine will act as a brake

Modern fuel injections do indeed use virtually no fuel when used in engine braking (when the computer detects that the driveshaft is driving the engine to go faster than the throttle position would have it turn.) Idle, on the other hand does need fuel.

So if you are going down a hill and you can maintain speed in 5th or 6th gear, you save gas compared to if you put it in neutral.

But in the case of his Volga, which I assume uses a carburator, I don't believe it works the same way, and it uses as much fuel as it would at idle, or probably a bit more.
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GQfluffy
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RE: Question About Using Neutral In Automatic Car

Sun Nov 26, 2006 2:29 pm

Quoting Jamie757 (Reply 14):
Think of it like this, if the engine is braking as well, then you effectively have two brakes working for you. This means less wear on your brake pads. As said by Go3Team previously, it doesn't do the engine any harm (or abuse as you put it).

Eh...you are putting some back presure on the engine...and in half a dozen years of driving manual transmissions...when I would use the gears to slow me down...it would eat gas milage...
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Jamie757
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RE: Question About Using Neutral In Automatic Car

Sun Nov 26, 2006 2:40 pm

Quoting GQfluffy (Reply 16):
Eh...you are putting some back presure on the engine...and in half a dozen years of driving manual transmissions...when I would use the gears to slow me down...it would eat gas milage...

Fair point, going down through all the gears isn't necessary though. Engine braking works in high gears too. If I'm braking to a standstill I'll leave it in the gear I'm using when I start braking. When I'm stationary or thereabouts, the clutch goes in, and I'll shift to a lower gear. Block changing is much easier. I see the fuel consumption figures on my trip computer drop as soon as I start braking.

Rgds.
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Klaus
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RE: Question About Using Neutral In Automatic Car

Sun Nov 26, 2006 2:55 pm

Quoting Go3Team (Reply 11):
You cause more abuse by starting your engine than using it as a brake.

That's not the alternative in that case. Actually, it would go the other way around - letting the motor management cut out and restart the engine would go more into that direction.

Quoting Go3Team (Reply 11):
Using the engine for compression braking in no way harms the engine.

Not true.

Especially not regarding the transmission. Switching loads - as between pulling the car and pushing the motor - is absolutely the worst you could do to any mechanical gearbox, and unfortunately unavoidable when using the motor alternatingly for acceleration and as a brake. Softly disengaging and re-engaging the forward pulling force causes a lot less stress on the gearbox.

And the motor lives or dies to a large extent by the amount of revolutions it has to perform. So having it pushed at high rpms is certainly not good for it!

Quoting Go3Team (Reply 11):
The fuel saved probably wouldn't even cover the costs of the brake pads.

I routinely avoid braking by looking ahead and letting it run in neutral where appropriate. If anything, I use the brakes less than most people I've watched driving so far.

Quoting Jamie757 (Reply 14):
I do, it gives me/you a lot more control whilst slowing the vehicle down.

Not really. When using the motor as a brake you have a very limited range of braking force available (which is also constantly changing according to the current state of the motor). If you happen to need to increase it beyond that limit, you need to switch to the actual brakes in addition. And if you need to brake faster than the motor wants to slow down, you'd have to de-clutch as well. Not really what I'd call optimal control.

The real brakes allow for a positive and continuous control of the braking force right up to the maximum possible.

Quoting Jamie757 (Reply 14):
Think of it like this, if the engine is braking as well, then you effectively have two brakes working for you.

That's a dangerous fallacy. In a quick deceleration you'll actually find the motor counteracting your braking because it can't spin down fast enough! If you forget to hit the clutch quickly enough, you'll be in trouble!

You'll get into a pickle a lot easier when being accustomed to motor braking - and you'll lose precious meters of braking distance exactly when it counts the most!
 
Go3Team
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RE: Question About Using Neutral In Automatic Car

Sun Nov 26, 2006 3:02 pm

Quoting Cfalk (Reply 15):
How can you damage it?The gears are simply spinning without being meshed.

It's all in how the transmission is lubricated. No lubrication = bad.
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Jamie757
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RE: Question About Using Neutral In Automatic Car

Sun Nov 26, 2006 3:27 pm

Quoting Klaus (Reply 18):
That's not the alternative in that case. Actually, it would go the other way around - letting the motor management cut out and restart the engine would go more into that direction.

The engine doesn't stop and restart when you lift off the gas, it slows down.

Quoting Klaus (Reply 18):
Softly disengaging and re-engaging the forward pulling force causes a lot less stress on the gearbox.

What you really mean here is slipping the clutch.

Quoting Klaus (Reply 18):
I routinely avoid braking by looking ahead and letting it run in neutral where appropriate. If anything, I use the brakes less than most people I've watched driving so far.

Your clutch bearings will be expiring soon then.

Quoting Klaus (Reply 18):
That's a dangerous fallacy. In a quick deceleration you'll actually find the motor counteracting your braking because it can't spin down fast enough! If you forget to hit the clutch quickly enough, you'll be in trouble!

I don't know if your vehicle has ABS or EBA, but my handbook tells me how to use the footbrake in an emergency. Emergency braking and normal braking are different things entirely.

Rgds.
"I feel like a turkey who's just caught Bernard Matthews grinning at him!"
 
Klaus
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RE: Question About Using Neutral In Automatic Car

Sun Nov 26, 2006 3:43 pm

Quoting Jamie757 (Reply 20):
The engine doesn't stop and restart when you lift off the gas, it slows down.

It stops and restarts combustion. Which is one part of the equation.

Quoting Jamie757 (Reply 20):
What you really mean here is slipping the clutch.

Simply operating it properly, nothing excessive at all.

Quoting Jamie757 (Reply 20):
Your clutch bearings will be expiring soon then.

Nope. Over 265000km and still on the first motor, first gearbox and the first clutch.

As said above: It needs to be operated properly!

Quoting Jamie757 (Reply 20):
I don't know if your vehicle has ABS or EBA, but my handbook tells me how to use the footbrake in an emergency. Emergency braking and normal braking are different things entirely.

No. The former is almost always an extension of the latter, born out of quickly developing situations where you can't afford fiddling around with any more mechanics than you absolutely had to!
 
MrChips
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RE: Question About Using Neutral In Automatic Car

Sun Nov 26, 2006 6:09 pm

There is nothing wrong with coasting in gear, Klaus. It really does save you fuel, and there is no harm done to your transmission or clutch if you operate it the way that a manual transmission is supposed to be operated. As for emergency braking, I find it hard to believe that one's first reaction would be to downshift when they see a stopped car directly in front of them - 99.99% of people's first reactions would be to hammer the brake and the clutch simultaneously - I know I would do that.

Furthermore, what red-blooded male doesn't like the sound of a car in the overrun, as the exhaust makes all kinds of wonderful popping noises?

Quoting Klaus (Reply 18):
Switching loads - as between pulling the car and pushing the motor - is absolutely the worst you could do to any mechanical gearbox, and unfortunately unavoidable when using the motor alternatingly for acceleration and as a brake. Softly disengaging and re-engaging the forward pulling force causes a lot less stress on the gearbox.

That's why you rev match when you change gears up or especially down, to minimize the amount of clutch slippage that you need for a smooth change. Plus, it reduces the force on the synchromeshes in your transmission.

Top be honest, I've never been told that "switching loads" is bad for your transmission. If you do it abruptly with no rev-matching, the damage to your transmission is the least of your worries, as demonstrated by this guy:



If you don't rev match in a RWD car, you WILL do this at some point.

Quoting Klaus (Reply 18):

And the motor lives or dies to a large extent by the amount of revolutions it has to perform. So having it pushed at high rpms is certainly not good for it!

Not true - the motor lives and dies by the PRESSURES and TEMPERATURES it experiences; revolutions only come into play if you decide the redline doesn't mean anything.

[Edited 2006-11-26 10:12:03]
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Siren
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RE: Question About Using Neutral In Automatic Car

Sun Nov 26, 2006 6:23 pm

Quoting Shawn Patrick (Reply 4):
Why exactly is it bad for it?

Not just the torque converter as Jamie757 pointed out. Your planetaries are still rotating (they are analogous to gears in an automatic transmission). When you slip the car into neutral, they continue to rotate as they are still engaged to the driveshaft - all you've done by putting the car in neutral is disengage the forward clutch assembly. Everything in the transmission is still rotating, however the internal components are now not getting lubricated - and you overheat the transmission very quickly. The torque converter also overheats.
 
dl021
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RE: Question About Using Neutral In Automatic Car

Sun Nov 26, 2006 7:14 pm

aaaahhhhhh............no
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Go3Team
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RE: Question About Using Neutral In Automatic Car

Sun Nov 26, 2006 11:33 pm

Quoting MrChips (Reply 22):
That's why you rev match when you change gears up or especially down, to minimize the amount of clutch slippage that you need for a smooth change. Plus, it reduces the force on the synchromeshes in your transmission.

That was what I was also thinking, although my daily driver doesn't have synchronizers, so it has to be an exact match when putting it in the next gear. Saves on clutch wear as well, as I don't have to use it, unless starting or stopping.

Quoting Klaus (Reply 21):
It stops and restarts combustion. Which is one part of the equation.

Whether or not the vehicle is in gear, the vehicle is always combusting. Fuel is always being provided to the engine, unless it is off of course.

Quoting Klaus (Reply 18):
Especially not regarding the transmission. Switching loads -

Have you ever seen someone putting together a differential or transmission? Either are designed to handle loads on both ends. Transmissions/differentials have to be put together properly or to much of a load from either end could put it too much over to one side and tear it up.
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Klaus
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RE: Question About Using Neutral In Automatic Car

Mon Nov 27, 2006 12:24 am

Quoting MrChips (Reply 22):
There is nothing wrong with coasting in gear, Klaus. It really does save you fuel, and there is no harm done to your transmission or clutch if you operate it the way that a manual transmission is supposed to be operated.

It depends on your overall driving style, and no, I doubt that it saves fuel to invest energy into running the engine at high rpm when it could be in idle at the same time.

Quoting MrChips (Reply 22):
As for emergency braking, I find it hard to believe that one's first reaction would be to downshift when they see a stopped car directly in front of them - 99.99% of people's first reactions would be to hammer the brake and the clutch simultaneously - I know I would do that.

Downshifting is only another complication which can divert attention in critical situations. In many cases emergency braking develops out of a "normal" deceleration, and having the motor still connected at that point is just a bad idea.

Quoting MrChips (Reply 22):
Furthermore, what red-blooded male doesn't like the sound of a car in the overrun, as the exhaust makes all kinds of wonderful popping noises?

...sometimes even enriched by the sound of motor components being spewed out of the exhaust...?  mischievous 

Quoting MrChips (Reply 22):
That's why you rev match when you change gears up or especially down, to minimize the amount of clutch slippage that you need for a smooth change.

That's got nothing to do with it - whenever you're alternating between motor acceleration and motor braking (even without switching gears), the gearbox experiences a load switch, which is a major stress event.

Quoting MrChips (Reply 22):
Not true - the motor lives and dies by the PRESSURES and TEMPERATURES it experiences; revolutions only come into play if you decide the redline doesn't mean anything.

High rpms never come for free, even below the red line. I'm not talking about blowing up the engine right away, I'm talking about stressing the whole drive train repeatedly, thereby reducing its useful lifespan.

Quoting Go3Team (Reply 25):
Whether or not the vehicle is in gear, the vehicle is always combusting. Fuel is always being provided to the engine, unless it is off of course.

Modern injection engines stop combustion altogether when they're being pushed as far as I'm aware.

They're still aspirating, compressing and exhausting, however. And at higher rpms (such as when using the motor as a brake), the forces involved will just add to wear over time.

Quoting Go3Team (Reply 25):
Have you ever seen someone putting together a differential or transmission? Either are designed to handle loads on both ends.

Sure. But repeated stress will wear them down faster over time.
 
N231YE
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RE: Question About Using Neutral In Automatic Car

Mon Nov 27, 2006 12:40 am

I unfortunately cannot do this trick (whether or not it works). Since I drive hybrid, if I put my CVT into neutral, than it would prevent the electric motor from regeneratively braking-doubling up as a generator and recharging the batteries from the car's inertia.
 
Klaus
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RE: Question About Using Neutral In Automatic Car

Mon Nov 27, 2006 1:06 am

Quoting N231YE (Reply 27):
I unfortunately cannot do this trick (whether or not it works). Since I drive hybrid, if I put my CVT into neutral, than it would prevent the electric motor from regeneratively braking-doubling up as a generator and recharging the batteries from the car's inertia.

There's nothing unfortunate about it at all - a hybrid car gains its advantage by not wasting the braking energy at all but saving it for the next acceleration instead. If it functions properly, it makes much of our discussion moot.

If you're using the car for the kind of driving hybrids excel at, it's pretty much the best one could do (except driving less in the first place! ).
 
trvyyz
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RE: Question About Using Neutral In Automatic Car

Mon Nov 27, 2006 1:36 am

What a load of blunders from a bunch of know it all anetters.
But some have got it right, of course.

Quoting Cfalk (Reply 15):
That's the way they were designed to be used. How can you damage it?The gears are simply spinning without being meshed.

 checkmark 

Only possible cons while going downhill on NEUTRAL (manual) are more braking if you have to stop and if you have to resume putting the wrong gear can screw things.

Quoting Boston92 (Reply 6):
When going 70 down a hill, in neutral, and you rev the engine, it gets up to 5 or 6 thousand RPM, and you risk blowing your engine.

How exactly is that? IN NEUTRAL the revs are independent of the speed of the vehicle.
 
Jamie757
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RE: Question About Using Neutral In Automatic Car

Mon Nov 27, 2006 3:53 am

Quoting TRVYYZ (Reply 29):
What a load of blunders from a bunch of know it all anetters.

 checkmark 

Quoting TRVYYZ (Reply 29):
Only possible cons while going downhill on NEUTRAL (manual) are more braking if you have to stop and if you have to resume putting the wrong gear can screw things.

There's a couple more, how about brake wear? Brake fade, which can sometimes lead to brake failure. What if the engine stalls? The vacuum assistance starts to disappear from your brakes. Not exactly what I'd call 'optimum control' or 'using it properly.'

There are no positive things to be said about coasting (automatic or manual) in my opinion. For those who are interested, take a look here...

http://www.rospa.com/roadsafety/advice/driving/automatic_gearboxes.htm

 Smile

Rgds.
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JAGflyer
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RE: Question About Using Neutral In Automatic Car

Mon Nov 27, 2006 4:10 am

Why don't we all agree on this; use neutral when you take your car to the carwash and it says to do so. Otherwise don't use it. Its not worth the strength to put the car in neutral to save a few cents of gas.

[Edited 2006-11-26 20:10:46]
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Klaus
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RE: Question About Using Neutral In Automatic Car

Mon Nov 27, 2006 4:12 am

Quoting Jamie757 (Reply 30):
There's a couple more, how about brake wear?

Much cheaper to fix than replacing motor, gearbox and clutch. And with halfway intelligent driving still rare enough.

Quoting Jamie757 (Reply 30):
Brake fade, which can sometimes lead to brake failure.

Happens only under rare circumstances. In those special cases it's a different deal and motor braking can make sense, but that's not a valid argument for standard driving situations.

Quoting Jamie757 (Reply 30):
What if the engine stalls? The vacuum assistance starts to disappear from your brakes.

It usually holds long enough to stop. And it's clearly a rare emergency situation which would justify using any means possible, even those which don't make sense in normal operation.

Conversely, should the motor freeze up while you're using it as a brake, you'd need extremely quick reflexes to avoid a major crash as a result. It's very rare, but we've already been at rare emergencies, haven't we?

Quoting Jamie757 (Reply 30):
Not exactly what I'd call 'optimum control' or 'using it properly.

You haven't presented any arguments for the use of motor braking under any but rare emergency situations. And none to counter my statement that it adds complications and potential loss of reaction speed when you suddenly have to decelerate.

Quoting Jamie757 (Reply 30):
There are no positive things to be said about coasting (automatic or manual) in my opinion. For those who are interested, take a look here...

Your link seems to deal exclusively with automatic transmissions, not with manuals. I have no interest in automatics and have not said anything about those. They're a lost cause anyway.

[Edited 2006-11-26 20:16:28]
 
sv2008
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RE: Question About Using Neutral In Automatic Car

Mon Nov 27, 2006 4:46 am

Engine braking is much safer, theres no reason not to use it.

You aren't saving enough fuel for it to be worth it (putting it in neutral), and theres not going to be any extra engine wear.
 
Klaus
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RE: Question About Using Neutral In Automatic Car

Mon Nov 27, 2006 4:51 am

Quoting Sv2008 (Reply 33):
Engine braking is much safer,

There are clearly reasons why it's less safe (see above); Why is it supposed to be safer, then?

Quoting Sv2008 (Reply 33):
theres no reason not to use it.

See above.

Quoting Sv2008 (Reply 33):
and theres not going to be any extra engine wear.

Yeah. Keeping the engine at much higher rpms than it would need to be in certainly won't ever add to wear and tear right?
 
sv2008
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RE: Question About Using Neutral In Automatic Car

Mon Nov 27, 2006 5:31 am

Quote:

Yeah. Keeping the engine at much higher rpms than it would need to be in certainly won't ever add to wear and tear right?

Unless you live in mountains, it's such a short time, it makes little difference.

And anything below 3000 rpm on a petrol dosn't cause any extra wear that you should worry about.

Well worth it for extra safety.

Quote:

There are clearly reasons why it's less safe (see above); Why is it supposed to be safer, then?

Engine braking is obviously safer because the brakes can overheat on a long hill, losing their ability to stop the car without it - fade.

It also reduces the need to use the brakes in the first place - the descent is already controlled so only a little extra brake application is needed - the brakes are unlikely to overheat then.

All that stuff about the engine spinning down I think is rubbish - brakes on car are far too powerful to worry about that. IT makes no noticeable difference.
 
Klaus
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RE: Question About Using Neutral In Automatic Car

Mon Nov 27, 2006 5:45 am

Quoting Sv2008 (Reply 35):
Engine braking is obviously safer because the brakes can overheat on a long hill, losing their ability to stop the car without it - fade.

That applies only to very long descents at high load or to trucks; And I already said above that in those very rare circumstances motor braking can be useful as an exception. It's a completely different picture pretty much everywhere else.

If your brakes are fading outside of exceptional circumstances, your car is unsafe to begin with or your driving style is highly dangerous on its own.

Quoting Sv2008 (Reply 35):
All that stuff about the engine spinning down I think is rubbish - brakes on car are far too powerful to worry about that. IT makes no noticeable difference.

It would be dangerous to rely on that to be the case - you'll add to your braking distance as soon as your deceleration exceeds that of the engine, especially in the lower gears.
 
Jamie757
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RE: Question About Using Neutral In Automatic Car

Mon Nov 27, 2006 5:50 am

Quoting Klaus (Reply 32):
Much cheaper to fix than replacing motor, gearbox and clutch.

As was stated earlier in the thread, engines, transmissions and clutches are designed and built to be operated using compression braking. The switching of loads that you describe is not a big issue, providing it is done smoothly.

Quoting Klaus (Reply 32):
Happens only under rare circumstances. In those special cases it's a different deal and motor braking can make sense, but that's not a valid argument for standard driving situations.



Quoting Klaus (Reply 32):
It usually holds long enough to stop. And it's clearly a rare emergency situation which would justify using any means possible, even those which don't make sense in normal operation.

How do you know when these rare emergencies are going to happen though. Personally, I feel more comfortable in the knowledge that I have two systems braking for me, therefore if the brakes fail, I can still rely upon the engine to help me maintain control.

Quoting Klaus (Reply 32):
You haven't presented any arguments for the use of motor braking under any but rare emergency situations.

Under normal conditions I generally find that engine braking gives me and my passengers a smoother ride, it reduces wear and tear on my brakes and tyres, it uses less fuel and it gives me more control.

Quoting Klaus (Reply 32):
And none to counter my statement that it adds complications and potential loss of reaction speed when you suddenly have to decelerate.

It doesn't complicate anything if you know how to do it properly in the first place. As soon as your right foot comes off the gas, the engine begins to slow, in effect assisting the footbrake. No potential loss of reaction speed. It also helps to retain stability under braking.

Quoting Klaus (Reply 32):
Your link seems to deal exclusively with automatic transmissions, not with manuals

Yes, the original topic was about automatic transmissions.

Unfortunately, I couldn't find much about manual transmissions on the intraweb. However I will just add a small quote from a book that I have and it says, "Any form of coasting is wrong because - i) it reduces the driver's control, ii) you might have difficulty engaging a gear if something unexpected happened, iii) acceleration is not immediately available and iv) it would almost certainly lead to the vehicle gathering speed on a downhill stretch.

Interestingly, it's in the 'know the basics' section.  Wink

Rgds.
"I feel like a turkey who's just caught Bernard Matthews grinning at him!"
 
sv2008
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RE: Question About Using Neutral In Automatic Car

Mon Nov 27, 2006 5:55 am

Quote:
your deceleration exceeds that of the engine
you'll add to your braking distance

I know just from driving that the brakes are so powerful, any difference is going to be tiny, if it even exists.

The brakes will force the engine to slow if needed, adding to braking difference is practically nothing.

As someone else said the amount of fuel is small, so engine power is tiny at that point anyway.

The advantages are far more than any disadvantage. I think it's crazy to coast around, everyone is taught when learning never to do that.
 
Go3Team
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RE: Question About Using Neutral In Automatic Car

Mon Nov 27, 2006 6:05 am

Ahhh, just remembered something... Coasting in neutal is considered illegal in some localities. Can be considered reckless driving - failing to maintain proper control.
Yay Pudding!
 
ArmitageShanks
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RE: Question About Using Neutral In Automatic Car

Mon Nov 27, 2006 7:14 am

Quoting Go3Team (Reply 39):
Coasting in neutal is considered illegal in some localities. Can be considered reckless driving - failing to maintain proper control.

There are signs on some of the local highways stating that here in Tennessee.
 
Go3Team
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RE: Question About Using Neutral In Automatic Car

Mon Nov 27, 2006 7:19 am

Quoting ArmitageShanks (Reply 40):
There are signs on some of the local highways stating that here in Tennessee.

Some truck drivers like to kick it out of gear going down some of those nice TN downgrades. Worked with a guy that blew up a motor + trans doing that trying to get it back into gear. He got fired.
Yay Pudding!
 
bristolflyer
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RE: Question About Using Neutral In Automatic Car

Mon Nov 27, 2006 8:46 am

Quoting Tu204 (Reply 9):
Quoting Go3Team (Reply 1):
You also risk the possibility of accidently putting it in reverse while moving forward.

I don't know about other cars, but in my BMW it does blocks R unless you are standing still. It simply wont engage Reverse if you are moving quickly.

Plus also with every auto 'box I have ever driven you can shift from drive to neutral without the 'secondary action' - ie depressing the button on the shift knob or pulling the lever towards you on a behind-the-wheel shifter. To move it into R you have to do these extra things, as with shifting it out of 'P', hence if you know what you're doing you won't accidentally put in 'R'.
Fortune favours the brave
 
DrDeke
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RE: Question About Using Neutral In Automatic Car

Tue Nov 28, 2006 2:47 am

Quoting TRVYYZ (Reply 29):
How exactly is that? IN NEUTRAL the revs are independent of the speed of the vehicle.

I assumed he meant that if you forget you had it in neutral and stepped on the gas to accelerate, the engine would rev much faster than you expected it to for a given throttle position.

-DrDeke
If you don't want it known, don't say it on a phone.
 
trvyyz
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RE: Question About Using Neutral In Automatic Car

Tue Nov 28, 2006 3:44 am

Quoting DrDeke (Reply 43):
assumed he meant that if you forget you had it in neutral and stepped on the gas to accelerate

No, that is not what he meant. He had specified a speed of 70 (mph as he in US), it was as if the revs would be more because of the speed.
 
bill142
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RE: Question About Using Neutral In Automatic Car

Tue Nov 28, 2006 7:18 am

Going down a hill in neutral is the stupidest thing ever. Gravity takes over and by the time you come to the bottom of the hill you need to use your breaks so much that it's essentially pointless. Use the gears to control the speed of the car
 
glydrflyr
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RE: Question About Using Neutral In Automatic Car

Tue Nov 28, 2006 8:41 am

All I gotta say about this is that we have a half dozen Lincoln Town Cars in limo service, all driven by professional drivers, and not one of them has less than 400,00 miles on the ORIGINAL engine and ORIGINAL tranny, and we coast them regularly. My personal car gets over 23 mpg (that's cause I pay for the gas) and the least efficient one gets 21.5 mpg average. If we do not coast on a long doen hill, we can disengage 4th gear, (overdrive) if we wish by depressing a button on the end of the gear selector stalk to prevent the car from over running the speed limit, especially if we know that we can expect to see a cop at the bottom of the hill with a radar gun. (Laser speed guns are illegal in NJ.) Otherwise, we have seen no ill effects from coasting and it very definitely improves the gas mileage. Brake Fade???? Are you guys coasting down the Alps with your feet on the brakes? Brake fade was something you got back in the fifties and sixties with drum brakes.
if ya gotta crash, hit something soft and cheap!
 
Klaus
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RE: Question About Using Neutral In Automatic Car

Tue Nov 28, 2006 7:57 pm

Quoting Bill142 (Reply 45):
Going down a hill in neutral is the stupidest thing ever. Gravity takes over and by the time you come to the bottom of the hill you need to use your breaks so much that it's essentially pointless.

I may have forgotten to mention it, but knowing how to drive was sort of implied as a basic requirement...!  mischievous 

This is all primarily a question of driving style (apart from exceptional circumstances); And driving appropriately under the circumstances is simply a necessity.

Beyond that, most people don't know or care much about fuel consumption or mechanical wear - and it shows.

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