Automatic: When Stopped in Traffic, Shift to Neutral?

[SilverGGA]

Aamco suggests to shift to neutral when stopped in traffic to extend transmission life by stressing the ATF less. Is this true? Could someone in the knows comment on this?

http://www.aamco.com/main/transmissiontips/tip_7.html

 

[Big Jim]

I would be hard pressed to try to say that this is unconditionally true for all automatic transmission cars.

Did you see the disclaimer at the bottom of the page? Only necessary when you know you will be setting with an idleing engine for a prolonged period. Don't do it for normal traffic stops. Or something close to that.

If you are going to be setting for very long, it may be best to shut the engine off.

You are more likely to have a heating problem from the low engine speed than from additional trans heat from being in gear. Slipping the shifter into neutral or park brings up the idle speed, and on cars with a belt driven fan, brings up the fan speed to bring more air across the radiator.

I don't know, the whole thing seems a bit lame.

 

[Gary Allan]

They used to recommend this on 70's mopars. The "slap stick shifter" had a convenient feature for doing this. It would go from DRIVE to NEUTRAL without pushing the button ..but wouldn't go into Reverse. This was for the more powerful engine/trans combos.

Some later model transmissions (later model to me is probably anything from the mid 80's forward

) had a feature where the cooling circuit was not operational in PARK ..but was in NEUTRAL.

Converter slippage generates heat. There is less when in N then in D. The turbine and impeller are near the same speed in Neutral.

Add all that to Big Jim's comments and what do you have? Don't bother (also as Big Jim said) unless you're in extended idle situations.

Add a BIG cooler and worry much less (you will still worry

)

 

[kanling]

I do it if I know I'm going to be sitting at the light for a minute or so. It is supposed to save gas, miniscule as the savings might be.

 

[unDummy]

And, and wear out that transmission every time you shift it in/out of drive!

Leave it in drive.
If you want a longer lasting transmission, add:
more cooling
more filtration
more frequent ATF changes

 

[MolaKule]

quote:

---

If you want a longer lasting transmission, add:
more cooling
more filtration
more frequent ATF changes

---

Absolutely.

 

[labman]

I can't believe clunking in and out of gear at every light can help the transmission. And even if it does, how about wear and tear on universals including CV joints and differentials? How about wear and tear on rear bumpers while you mess around shifting into drive after the light turns green and get rear ended? How about wear and tear on your transmission because the idiot in front of you and a whole line of cars to stop while he shifts into gear?

 

[bmwtechguy]

quote:
-------------------------------------------------
If you want a longer lasting transmission, add:
more cooling
more filtration
more frequent ATF changes
-------------------------------------------------

and/or better quality fluid such as S/F, Amsoil, Mobil 1, or Redline, etc.!

 

[nascarnation]

This is already a feature on the big Allisons.
Soon to be found on car/light truck automatics:

The Allison Highway Series was designed for high density, stop-and-go duty cycles. A feature called Reduced Engine Load at Stop (RELS), available on the Allison 3000 HS, ensures that the transmission won’t waste energy when the vehicle is at a full stop. With RELS, the transmission reduces the load on the engine, achieving benefits similar to shifting into Neutral. This not only saves fuel, it reduces overall vehicular emissions.

With full electronics the powertrain can sense an idle stopped condition and release a clutch inside the trans(knowing that the wheel brake is applied - via the vehicle CAN network - to keep from rolling). And yes design changes need to be made to accomodate the extra clutch engagement cycles.

 

[SilverGGA]

Coming to think of this, the new generation Subaru Legacy already does it. The computer will automatically put the transmission to neutral when the car is stopped. They say it's an energy saving measure.

So what is involved when the transmission is shifted from "drive" to "neutral", and when from "neutral" to "drive" when the light turns green? Wondering what kind of wear will incur.

I am not really interested in actually shifting to neutral when stopped. I just find it an interesting topic to investigate upon.

 

[unDummy]

Does anyone have the FSM for the new Subie?
I'd love to know the parameters for disengagement and what they call/market it as.

Clutches would have to engage quicker then the foot moving from the brake to the gas pedal, because you'll get some drivetrain shock or lag.