Does this hurt the transmission?

SPARTUS · Post by **SPARTUS** » Mon Mar 01, 2004 6:53 pm

When driving an automatic transmission, does it hurt the transmission to put it in neutral while the car is still rolling, in drive?

Also, does it hurt the transmission, if your car is rolling forward in neutral, and you put it in drive without letting the car come to a halt first?

thanks

91White-T · Post by **91White-T** » Mon Mar 01, 2004 7:13 pm

No and No. If its rolling backwards, different story.

ciper · Post by **ciper** » Mon Mar 01, 2004 8:02 pm

As long as the engine is running its okay to roll in neurtal. DO NOT roll the car in neutral with the engine off.

I hope you arent shifting in neutral at stops

QuickDrive · Post by **QuickDrive** » Mon Mar 01, 2004 9:12 pm

While we're on the topic of "does this hurt"

How many of you drive around city driving in 3 instead of "D" There shouldn't be any problem with that right?

A lot of the roads around here have speed ratings between 60 and 80 kph, which in my car it wants 4th whenever I'm at around 80 but then switches to third and back and forth to 4th around those speeds, so I keep it in 3..

This is my first auto, and I'm assuming it's just keeping the car from shifting into 4th, but I might as well ask...

mTk · Post by **mTk** » Mon Mar 01, 2004 9:21 pm

no problem with doing that quick.

MK

ciper · Post by **ciper** » Mon Mar 01, 2004 11:02 pm

Everyone should drive around in 3, no reason to put extra stress on the drivetrain and cause additional downshifts when you need to accellerate.

You dont need 4th gear until cruising at over 55MPH. At or below 55 and 3rd is the best choice. I drive my car in second if I cruise at or below 25mph.

SPARTUS · Post by **SPARTUS** » Mon Mar 01, 2004 11:56 pm

no, i don't shift into neutral everytime i come to a halt. just wanted to know your expertise opinion, that's all =)

also, i'm guessing the ppl who are backing up and pop their car into drive, without making a complete stop ruin their transmission? what exactly gets ruined?

94L_wagon · Post by **94L_wagon** » Tue Mar 16, 2004 1:10 am

I drive mainly manual transmissions and am a bit ignorant of autos, but why would shifting to Neutral in an auto be harmful when you are standing still?

Surely it would take strain off the drivetrain which is trying to 'go' in first gear, and being fought by the brakes?

ciper · Post by **ciper** » Tue Mar 16, 2004 2:21 am

Because you allow the TC output to spin, then cause the forward drive clutches to engauge, OVER and OVER. Instead let the fluid take the energy.

94L_wagon · Post by **94L_wagon** » Tue Mar 16, 2004 4:03 am

Interesting - thanks.

elevatorguy · Post by **elevatorguy** » Sat Oct 09, 2004 11:07 pm

I've put over 70,000mi on my 91 legacy & dropped it into N approaching every red light & most stop-signs over the past 7yrs.
Bought it used.. the odometer is at 146,000mi.. no problems yet.. I'll keep you posted

BTW awesome forum guys.. glad I found you!!

Binford · Post by **Binford** » Sun Oct 10, 2004 3:08 am

Elevatorguy- WHY would you do that?

elevatorguy · Post by **elevatorguy** » Sun Oct 10, 2004 4:06 pm

Heat is the #1 killer of transmissions! Here in TX heat is one of many things we've got plenty of!
Why do it?
Takes load off the engine and tranny by stopping xfer of energy to the tranny.
In city (stop & go) tranny does little/no breaking, the engine and tranny are still trying to accelerate the car while you're trying to decelerate with your brakes.
Why sit there with your foot on the brakes fighting the engine for the duration of the light? The energy absorbed by the fluid (which is converted into heat), is dissipated through the radiator (the same one that's trying to cool your engine - which is under load because it's still trying to push you forward)
Yes you may get a little more wear on your brakes.. but that's negligable compared to ANY tranny repair.
Ever noticed you can slide back & forth between D and N without depressing the button? I've never heard of another reason why they make em that way. (may hear a few now though.. anyone??)

THAWA · Post by **THAWA** » Sun Oct 10, 2004 4:19 pm

interesting stuff, but isn't the ATF oil pump disconnected when it's in neutral? Wouldn't that hurt the trans more? And I assume you have an auxillary ATF cooler right?

elevatorguy · Post by **elevatorguy** » Mon Oct 11, 2004 4:14 pm

It's a stock rad.. no aux cooler (mostly 1 passenger & no towing)
re. oil pump disconnected.. Can't see how that would hurt the tranny any more than putting the car in park when you're waiting/done driving does... still removes a direct source of additional heat to the tranny & rad.

I'd love to hear from a Subaru Engineer on the subject..
There's got to be an official Subaru study/stance on this somewhere.

entirelyturbo · Post by **entirelyturbo** » Tue Oct 12, 2004 1:38 am

I'm no authority on autos, but it makes no sense to put it in N if you ask me.

The engine isn't doing all that much work spinning ATF in the TC at idle, so by doing this, you won't help your gas mileage that much. But the fact that you keep disengaging the transmission then re-engaging it is hard enough on the transmission.

As THAWA said, if you're worried about AT heat, get an aux cooler. That will do way more than putting the tranny in N at stops.

THAWA · Post by **THAWA** » Tue Oct 12, 2004 3:01 am

My reasoning is, if the oil pump isn't circulating the atf through the tranny, the shafts will still be rotating without being cooled by the atf until you stop. This is the same thing with manuals (or so i'm told). The reason this shouldn't be a problem when you're stopped is nothing is rotating shaftwise. And yes if you're that concerned about heat (and everyone should be) you need an aux atf cooler

elevatorguy · Post by **elevatorguy** » Tue Oct 12, 2004 7:20 pm

Hmmm... good point.. even so with the engine disengaged there would be minimal resistance on the fins = low heat generation.

re. an aux cooler - If I did a lot of daytime driving in the summer here, or carried more than 2 pers regularly, no ques I'd put one in.. but i don't & the ATF light has never been lit..

Personally even more than heat concerns - I don't like to have my foot jammed on the brake for the duration of a light, or the thought of the engine that's powering my AC to be under additional nonproductive load. (just my preference)

Just for kicks try it for one trip... I dare you!!

re. mileage.. my guage runs 10gal E to F , the odometer is at 303mi and it just hit E. We're at $1.81US locally.. each time I drive by the pumps & look at all the pretty SUVs lining up, I like this car more

On another note.. Ciper's previous post about driving in 3rd was dead on the money. I never thought about the number of times it cycled in & out of forth until I left it in 3rd while off the highway the past couple of days. WHAT A DIFFERENCE! The tranny does a little more breaking coming to lights etc. too (expected but not prevously applied).

While I'm at it.. I think I've got something (paper, leaf) hitting the blades of my interior blower (started getting a noise lihe a hockey card hitting the spokes of a bike last week turned off/not used since) . Consulted Chilton's & it looks like I'll need to pull the glove box..and maybe more.. anyone got any pointers?
Thanks

THAWA · Post by **THAWA** » Wed Oct 13, 2004 2:54 am

um, i'm not talking about the torque convertor, I'm talking about the input shaft and all taht stuff inside the tranny that rotates based on vehicle speed and not engine speed. when it's rotating it is supposed to have atf cooling it, and AFAIK there's no atf cycling while in neutral.

it doesn't matter if you do daytime or nighttime driving, or if you weigh 10 lbs or have a full car load. ATF is very sensitive to heat, it doesnt take much to burn it. The atf light is set at a very high temperature, higher than the temp needed to actually burn the atf IIRC. So if you're just going by the AT OIL TEMP light you probably wont see it anytime soon, but you will be burning it. Sort of how the gas light wont come on until you're down to the reserve amount. I just wish i would've known this info before my trans died.

If I had an auto still I wouldn't do it assuming everything I said is correct. If you really want to conserve the engine wait until you come to a complete stop and then put the trans in neutral. A much safer way to do it.

As for the blower I do believe you just remove the glove box and it's staring you in the face. Dunno what you have to do to remove it though.

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Does this hurt the transmission?

Does this hurt the transmission?