Topic: Is this bad for my automatic?

[articsteve]

Why would you want to do that, brakes are much cheaper than transmissions

You're traveling 100 kph on a 80kph Ontario highway.  You find yourself descending a long hill and your speed is increasing, but you're concerned about getting picked off by the OPP who will nail your +ss over 100 kph.

You've got two choices:

Apply the brake lightly and ride that all the way down glazing your pads.  This is what most ppl do.

Or, slide the floor shifter down one gear and let the engine brake the vehicle just the same as should be done in a standard shift car.  Gate shifters are great for this.

I would certainly avoid buying a traditional automatic with flappy paddles.   

[airbalancer]

Buy a Prius and charge up the battery descending a long hill 

[aaronk]

...
Putting into neutral at lites is pointless.
 

Well, it isn't pointless really. If you think about how an automatic works, in Drive the car is always under power. When you're stopped at a light you are literally holding the car back with your brake pedal. If I know the mechanics correctly, shifting into neutral stops the forward power of the wheels (and hence use of fuel) and saves gas. Idling is terrible for cars, but it's less terrible in neutral.

[articsteve]

Frankly I think you've gotta be a little nuts if at each traffic lite when you stop you shift into neutral and then focus on the red as if your at the drag strip waiting for the green lite to shift back again.

These modern OEM computers manage the idle in most vehicles supremely.  I betta ya when you shift into neutral your RPM climb a 100 or so rpm so in the end you're burning the same amount of gas.

One thing that you can't do in an automatic is COAST to a stop.  When this occurs the torque converter pump pressure and the actual transmission hydraulic pump are out of sync.

Like AB mentions, you need a Prius.  It does all that crazy sh*t for ya. 

[safristi]

  "little nuts" have nothing to do with it..............I put my balls onna TEE.......those lil baggers appreciate the care i gives 'em.....

[Gamefreak]

Or, slide the floor shifter down one gear and let the engine brake the vehicle just the same as should be done in a standard shift car.

Right, but how much extra gas does that burn?

[Leviathan]

...
Putting into neutral at lites is pointless.
 

Well, it isn't pointless really. If you think about how an automatic works, in Drive the car is always under power. When you're stopped at a light you are literally holding the car back with your brake pedal. If I know the mechanics correctly, shifting into neutral stops the forward power of the wheels (and hence use of fuel) and saves gas. Idling is terrible for cars, but it's less terrible in neutral.

Looky what I found:

Early Drives of Chevy Cruze Proof Days of Small-Car Skimping Over at GM
...
Among the NVH additions is neutral idle, which automatically shifts the car in neutral at stops. It creates a smoother idle, GM says, and helps conserve fuel.

It looks like newer auto trannies (easy Saf) are "shifting" to neutral on their own.

[articsteve]

 It looks like newer auto trannies (easy Saf) are "shifting" to neutral on their own.

In a Volt.  Great example 

Hybrids for sometime have turned the motor off at a stop. The only reason the Volt shifts into neutral is GM can't engineer a stop/start feature that is seamless.   

[mmret]

IIRC most stop-start things are timed such that one of the cylinders is in a position that is just barely past the usual ignition point, so that you just need a single spark and you're off to the races no?

[articsteve]

I don't know much about it.  I tend to view all vehicles as if they are out of warranty so this stop start thing sounds very expensive.

I don't believe they could do this stop/start thing on a conventional 4 stroke.   This Atkinson cycle motor with the different power and compression strokes might be key.

[tpl]

It looks like newer auto trannies (easy Saf) are "shifting" to neutral on their own.

In a Volt.  Great example 

Hybrids for sometime have turned the motor off at a stop. The only reason the Volt shifts into neutral is GM can't engineer a stop/start feature that is seamless.   

Cruze not Volt

[tpl]

I don't know much about it.  I tend to view all vehicles as if they are out of warranty so this stop start thing sounds very expensive.

I don't believe they could do this stop/start thing on a conventional 4 stroke.   This Atkinson cycle motor with the different power and compression strokes might be key.

You could do it on a conventional engine and in fact it was done back in the 1920s albeit accidentally.

The ECU "knows" where every piston is. So all that has to happen is that an injector is fired and a few sparks sent to the appropriate plug.  Get one piston going down on a "power stroke" although it won't be very powerful ( not enough compression, not enough vaporisation) and the ecu can  find another cylinder to fire and off you go. Probably would work more reliably with a direct injection engine.

The ancient way was that with bowl in piston combustion chambers and manual advance retard on the steering wheel helped by compression ratios of perhaps 6:1, sometimes a wiggle of the advance retard lever was enough to cause  the points to open and close and form a  spark.  Some of the time this would spark in the cylinder with a puddle of gas in the piston top. Lo and behold your car would just start.

[Leviathan]

It looks like newer auto trannies (easy Saf) are "shifting" to neutral on their own.

In a Volt.  Great example 

Hybrids for sometime have turned the motor off at a stop. The only reason the Volt shifts into neutral is GM can't engineer a stop/start feature that is seamless.   

Man are you daft. The link clearly says Cruze.

Volt doesn't need start/stop at lights because it is all electric at that point regardless of battery charge.

[articsteve]

Volt doesn't need start/stop at lights because it is all electric at that point regardless of battery charge.

I suppose.  But the generator keeps on running so whats the point anyways.



Among the NVH additions is neutral idle, which automatically shifts the car in neutral at stops. It creates a smoother idle, GM says, and helps conserve fuel.

That will be a nice fix out of warranty.

[Leviathan]

Must. Not. Feed. The Troll.....

[aaronk]

Frankly I think you've gotta be a little nuts if at each traffic lite when you stop you shift into neutral and then focus on the red as if your at the drag strip waiting for the green lite to shift back again.
These modern OEM computers manage the idle in most vehicles supremely.  I betta ya when you shift into neutral your RPM climb a 100 or so rpm so in the end you're burning the same amount of gas.
One thing that you can't do in an automatic is COAST to a stop.  When this occurs the torque converter pump pressure and the actual transmission hydraulic pump are out of sync.
Like AB mentions, you need a Prius.  It does all that crazy sh*t for ya. 

Maybe in the newest cars the manufacturers have heard my woes, but on most cars pre-2010 you'll save fuel by shifting into neutral during long stops. Try pulling up to a stop in 'D' and let off the brake - what happens? Yes, the car moves forward...you're holding it back with your brakes. Admittedly, this may be a bit obsessive, but I like to think of it as an aversion to laziness that ends up saving money. I do a lot of things most drivers don't, like use signals and try to stay in the lines - so paint me as 'nuts'. As I said, I usually drive a manual, so I'm used to shifting.

As for being stopped at the lights, don't most people watch the colour to see when it turns? 

[tpl]

As for being stopped at the lights, don't most people watch the colour to see when it turns?

I think that most people have an eye to brain delay line for green lights...about 5 seconds and an even longer one if the green is in the shape of an arrow...like 10 more seconds.