Automatic Transmissions in General

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fordtech28

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May 12, 2006

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Riverside Cali.

Apr 10, 2008

#1

• Apr 10, 2008

• #1

This is a noob question I have asked people what would happened if I put a automatic transmission in neutral down a hill lets say in traffic .I got different responses some say it hurts the transmission some say it doesnt do anything does anybody know if it hurts the transmission or not if I coast in neutral down a hill.

 

toyman

10 Year Member

Jul 19, 2007

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Vernon BC

Apr 10, 2008

#2

• Apr 10, 2008

• #2

fordtech28 said:

This is a noob question I have asked people what would happened if I put a automatic transmission in neutral down a hill lets say in traffic .I got different responses some say it hurts the transmission some say it doesnt do anything does anybody know if it hurts the transmission or not if I coast in neutral down a hill.

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Besides being unlawful and perhaps dangerous why would you want to do that. If there is no need for fuel the PCM will stop the fuel flow through the injectors so you are not saving gas.

 

bill302

Active Member

Nov 2, 2005

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alabama,gadsden

Apr 10, 2008

#3

• Apr 10, 2008

• #3

plus anytime you have moving parts you have wear if its only moving the gear selector from drive to neutral and back it puts wear on the cable ect...and will cause premature wear....

 

divit250r

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Mar 31, 2005

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Columbia City, IN

Apr 11, 2008

#4

• Apr 11, 2008

• #4

toyman said:

Besides being unlawful and perhaps dangerous why would you want to do that. If there is no need for fuel the PCM will stop the fuel flow through the injectors so you are not saving gas.

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While I can't say for sure on a gas vehicle, my Superduty always gained MPG when I would free wheel up to a redlight or stop sign, I know that for a fact. The converter stayed locked and kept the engine spinning at a higher RPM than necessary. If the engine is running, there is fuel being used, so you may not gain much on a gasser in the long run.

My question is why do you say it's unlawful?? If it were unlawful to put the tranny in neutral, how could any of us drive a stick? Not being a jack, just curious what laws could come into play with this situation.

 

BlackVert

15 Year Member

Oct 3, 2003

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Bethesda, MD

Apr 11, 2008

#5

• Apr 11, 2008

• #5

i used to do that when i drove a stick

now, my aod behaves like you are describing (converter locked in 3rd causing engine braking and bringing up the rpms) and i sometimes am tempted to put it in neutral, but one time i tried to do it and i mistakenly moved it too far and put it into reverse intead. i immediately got it into neutral, but that reverse clunk didn't sound good, and i haven't tried it since. lucky for me i wasn't going very fast.

 

F

fordtech28

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May 12, 2006

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Riverside Cali.

Apr 11, 2008

#6

• Apr 11, 2008

• #6

toyman said:

Besides being unlawful and perhaps dangerous why would you want to do that. If there is no need for fuel the PCM will stop the fuel flow through the injectors so you are not saving gas.

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Unlawful I just was curious I sometimes do it when Im in traffic going down a two mile hill going maybe 10 -20 miles an hour and it has saved me gas by doing this method but I was worried about the transmission thats all

 

StinkinLincoln

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Dec 9, 2006

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Louisiana

Apr 11, 2008

#7

• Apr 11, 2008

• #7

1. you are not saving but a couple drops of gas.
2. its not going to hurt the tranny, the converter spins all the time, its attacked to the flywheel, the impellers inside it will change speed.
3. keep it in drive...its just smarter.
4. diesels do not have engine breaking, they are not like gas engines.

 

94GTCoupe

10 Year Member

May 7, 2006

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CA

Apr 11, 2008

#8

• Apr 11, 2008

• #8

when i still had the aode going down a large hill i would turn off the overdrive to slow me down so i would'nt have to ride the brake's,thats what your supposed to do.i dont see how putting the car i neutral would hurt the tranny.

 

94GTLaserRC

Squint as you approach, lest you be blinded by my

15 Year Member

May 7, 2002

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Ernan Says "here it comes... dushbag"

Apr 11, 2008

#9

• Apr 11, 2008

• #9

Just move to S. FL. We have no hills here!!

RC

 

toyman

10 Year Member

Jul 19, 2007

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Vernon BC

Apr 11, 2008

#10

• Apr 11, 2008

• #10

fordtech28 said:

Unlawful I just was curious I sometimes do it when Im in traffic going down a two mile hill going maybe 10 -20 miles an hour and it has saved me gas by doing this method but I was worried about the transmission thats all

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My reference to coasting being unlawful was specifically related to the British Columbia Motor Vehicle Act. The prohibition is as described in section 197:

Coasting down grade
197 When travelling down grade a driver must not coast with the gears of the vehicle in neutral or the clutch disengaged."

It is my understanding that most state MVA's also contain a similarly worded clause.

 

earleys94gt

Active Member

Aug 31, 2003

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Ashley, Ohio

Apr 11, 2008

#11

• Apr 11, 2008

• #11

The torque comvertor locks the third and overdrive clutches at cruising speeds(highway speeds).

I don't see how putting the tranny in nuetral will aid in fuel economy, so I would just leave it in drive.

I think what toyman is getting at is the 'friction' caused when the car is in gear will aid in slowing the car down, especially on a down grade. Otherwise, you need to use your brakes more; and you could end up with a 'runaway semi' senerio.

 

trav_19

New Member

Oct 29, 2006

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Jackson, MI

Apr 13, 2008

#12

• Apr 13, 2008

• #12

if your that worried about fuel sell the stang and get something else...your really not aiding anything maybe 6 cents a tankful lol