Shifting to neutral at stop light . . . Does this help reduce wear on a AT

[brianl703]

quote:

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Originally posted by labman:
Another thing that contributes to the glacial start at stop light is the popular practice of pulling up within a couple of feet of the next car. The closer you are, the longer you have to set before having what ever minimal distance you are willing to live with to the next car when you start moving.

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Leaving too much room between you and the car in front actually REDUCES the number of cars that can go through the green phase. This is straight from a traffic engineer working for VDOT.

Plus, it can block the left turn lane, further impacting traffic flow in a negative manner.

[ June 15, 2004, 10:46 AM: Message edited by: brianl703 ]

 

[Steve S]

Shifting to neutral at stoplights adds one more forward clutch application per cycle.Yes it causes more wear, will it matter in the whole picture ? I don't know . Leave it in gear it , it's not called an automatic nothing.

 

[Chris B.]

I have not read this whole(no time) but I have tried the neutral thing and my car always wants to rool away any way. So I always end up with my foot on the brake to stop the car. I have found this practice to be a bad idea. How are you guys not rolling away in neutral nd foot off the break???

 

[SteveD2]

quote:

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Originally posted by Chris B.:
How are you guys not rolling away in neutral nd foot off the break???

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Park?

 

[Chris B.]

Yeah, I just kept reading "neutral" though.

 

[crashz]

I used to beleive the same thing. So I would shift to neutral on long lights. Since I installed a tranny temp guage, I quit doing that. I notice no difference in temp at a long light, either in neutral or drive. The most noticable increase in temps are from accelerating. And the longer the acceleration, the hotter it gets. Also ambient temps play a huge role in transmission temps. Yesterday it was in the mid seventies and my tranny held steady at a little below 150 degrees F. This afternoon its 90 degrees and it was holding a little below 180 in traffic and 165 on the highway.

I'm of the opinion now that shifting to neutral in an automatic is just a nusance. Just leave it in gear for the period of time that you are waiting. If you want extra insurance against cooking your transmission, then install a cooler and guage.

 

[Horatio]

Not much to contribute except to say that I'm even worse about the "neutral thang"; I COAST to the light in neutral and wait. I asked my favourite transmission mechanic (who does well enoughl he doesn't really NEED my business) if I was really harming things by doing this and he said that it wasn't really adding any wear and in fact might actually be helping out with braking because with the trans disengaged, I had more vaccum for operating the brakes.

I think any difference in performance/durability is minor enough that it really can depend solely on a person's driving style to make the decision. I happen to like shifting to neutral and apparently so do a lot of other people. I admit that I have a bit of stickshift envy in this department because the car happens to be my Mustang that I didn't have a choice on the trans and haven't yet been able to afford a T5 swap.

Greg

 

[labman]

Vacuum doesn't stop the car, the brake lining does. See above posts on warping rotors. Besides, keeping the revs up in gear with the throttle closed, should give more vacuum than allowing it to idle. Coasting out of gear is illegal in some states.

 

[Titanium_Alloy]

quote:

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Originally posted by crashz:
I used to beleive the same thing. So I would shift to neutral on long lights. Since I installed a tranny temp guage, I quit doing that. I notice no difference in temp at a long light, either in neutral or drive. The most noticable increase in temps are from accelerating. And the longer the acceleration, the hotter it gets. Also ambient temps play a huge role in transmission temps. Yesterday it was in the mid seventies and my tranny held steady at a little below 150 degrees F. This afternoon its 90 degrees and it was holding a little below 180 in traffic and 165 on the highway.

I'm of the opinion now that shifting to neutral in an automatic is just a nusance. Just leave it in gear for the period of time that you are waiting. If you want extra insurance against cooking your transmission, then install a cooler and guage.

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What kind of car do you have? What is the mileage? Do you have AT cooler installed on this car? What ATF are you using? It would be intersting to know all these factors because they directly affect AT operation.

Thank you,

 

[nascarnation]

quote:

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Originally posted by lakeman:
I also shift into neutral at long red lights. The idea is to limit heat buildup in the torque converter.

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BINGO!
We have a winner.
This is a VERY GOOD THING for your auto trans.
The shifts from Neutral back to Drive (assuming they are made at hot idle speed) impart minimal energy to the clutch plates and driveline and don't impact durability at all. Now if you rev it to 3000 rpm and drop it into gear, that's a whole 'nother thing......

 

[XS650]

quote:

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Originally posted by nascarnation:

quote:

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Originally posted by lakeman:
I also shift into neutral at long red lights. The idea is to limit heat buildup in the torque converter.

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BINGO!
We have a winner.
This is a VERY GOOD THING for your auto trans.
The shifts from Neutral back to Drive (assuming they are made at hot idle speed)

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How much did the temperature increae in your TC at idle in gear? The last AT truck I had with trans temp gauge (a good one with 3/4 turn dial movement that was easy to read a 2 degree temp change) I could detect no difference in fluid temp between idle in gear and out of gear over a period of 5 minutes.

There is nearly insignificant amount of power being dissipated in a TC at idle unless you have a fast idle.

 

[VaderSS]

quote:

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Originally posted by crashz:
I used to beleive the same thing. So I would shift to neutral on long lights. Since I installed a tranny temp guage, I quit doing that. I notice no difference in temp at a long light, either in neutral or drive.

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Based on this observation I'd say shifting to neutral does more harm than good.

 

[brianl703]

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Originally posted by Horatio:
because with the trans disengaged, I had more vaccum for operating the brakes.

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Intake manifold vacuum should be higher when braking with the engine in gear than when braking with the transmission in neutral and the engine idling. Plus you get the engine braking you don't have when your coasting along in neutral.

Someone already mentioned it, but coasting to a stop in neutral is illegal in VA.

And, if the engine stalls for whatever reason while you're coasting and you must make a quick steering maneuver...well the results could be bad. Gee, I wonder if that's why it's illegal???

 

[labman]

I suspect the bans on coasting go back to when unsynchronized low gear manuals were more common than power steering.

 

[Horatio]

well if I ever make it to Va, I'll be sure to not coast in my '69 Mustang with no power steering

Greg

 

[Horatio]

Also, do auto tansmissions normally gear down along with the decrease in speed? I think the only way you'd get any braking benefit from them is if they geared down as the vehicle slowed which would definitely mean more wear on the clutches/bands and more heat in the converter

Greg

 

[S2000driver]

While coasting, if you put your transmission in neutral, your fuel system will have to USE FUEL to keep the engine running. However if you leave the transmission in gear it will not use any on most vehicles.

You're going to stop anyway. Leave it in gear and take it easier on your brakes and fuel consumption.

[ June 17, 2004, 08:09 PM: Message edited by: S2000driver ]

 

[OiledMustangGT]

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Originally posted by labman:
How about the wear on your back bumper because the guy coming up behind you expected you to go when the light turned green rather than play with the gear shift? People that fail to start out as soon as the light turns should be shot.

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This type of stuff really ****** me off. I **** near get rear ended twice a week at redlights on slopes b/c I have a manual trans and the person behind me is impatiant and waits 1" off my rear bumper

 

[XS650]

quote:

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Originally posted by labman:
I suspect the bans on coasting go back to when unsynchronized low gear manuals were more common than power steering.

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And brakes were real crap.

 

[labman]

quote:

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Originally posted by OiledMustangGT:

quote:

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Originally posted by labman:
How about the wear on your back bumper because the guy coming up behind you expected you to go when the light turned green rather than play with the gear shift? People that fail to start out as soon as the light turns should be shot.

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This type of stuff really ****** me off. I **** near get rear ended twice a week at redlights on slopes b/c I have a manual trans and the person behind me is impatiant and waits 1" off my rear bumper

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So save a few rounds for them.