Coasting with an Auto

[omgwtfbyobbq]

I think it's likely meant for a specific trans or family of transmissions since no automatic transmission I've driven downshifts after putting it into D from N or coast downshifts as the article puts it.

[bfg9000d]

I dont know. Bumping the transmission back and forth like that from N to D. Doesnt sound real good. After all you are playing with the transmission. You can be penny rich and dollar poor.

[omgwtfbyobbq]

I can do it all day long in my manual and all it'll do is wear the clutch. I don't see how it would do anything but the same thing (except w/ clutch packs) in an automatic. And, if it does blow, I'll have an excuse to drop a manual in. If you search the forum, you'll find there have been posters who have asked the manufacturer if doing it is ok, and they said it was np. I suppose that would be the best bet...

[bfg9000d]

For now what I have been doing is just letting off the gas. It seems to coast for quite a long time this way and my rpms are way below one when doing such. I have tried it a few times in my older car. I dont notice much difference when in gear or not. I guess it varies from car to car. I tried it once in my newer car it gave me a slightly longer coast but not enough to warrant me bumping the transmission all the time.

[popimp]

I'll be damned I looked in my owners manual and saw this statement:

CAUTION!
Damage to the transmission may occur if the following
precautions are not observed:
• Shift into PARK only after the vehicle has come to
a complete stop.
• Shift into or out of REVERSE only after the
vehicle has come to a complete stop and the
engine is at idle speed.
• Do not shift from REVERSE, PARK, or NEUTRAL
into any forward gear when the engine is above
idle speed.
• Before shifting into any gear, make sure your foot
is firmly on the brake pedal.

Should I stop doing my coasts in Neutral? I guess there goes my MPG.

[skewbe]

FWIW, here is my interpretations, taking into account a fair degree of manufacturer paranoia:

• Shift into PARK only after the vehicle has come to
a complete stop.
N/A, stay out of park when moving forward.

• Shift into or out of REVERSE only after the
vehicle has come to a complete stop and the
engine is at idle speed.
N/A, stay out of reverse when moving forward

• Do not shift from REVERSE, PARK, or NEUTRAL
into any forward gear when the engine is above
idle speed.
If I may paraphrase: "Don't do neutral drops and smoke the tires for a block!!"

• Before shifting into any gear, make sure your foot
is firmly on the brake pedal.
Because there is an interlock, or they don't want the car moving accidently.

[popimp]

So should I stop?

[2TonJellyBean]

skewbe's not worried... any chance of overshooting your neutral shift? if not, i wouldn't be either

[popimp]

Someone enlighten me. What is actually going on when I put the van in Neutral at 65mph then back to Drive at 55mph? Why would this or wouldn't this mess up the tranny? The owners manual says not to. So I'm curious. The FE gains are obviously there.

[skewbe]

I suspect that the "small bump" is the transmission going into gear, and that the bump is attenuated at higher speeds as the tranny picks a higher gear to put the van in.

I don't see that the owners says not to, it says to shift into drive with the engine idling (or do not shift into drive with it not idling). I assume the brake comment was to keep the car from moving accidently, just an assumption though.

Does the manual say anything about towing the van? Does it need a dolly or anything? Does oil circulate in the trans when in neutral w/engine idling?

Best bet would be to ask the manufacturer or someone with model specific info, tell them you are conducting countless FE experiments and need to switch from neutral to drive and vice versa at various speeds. Tell them you are on a closed course too so they don't get too sidetracked.