# downshifting an automatic



## Guest (Aug 13, 2002)

yo, wasup, had a question for ya'. does downshifting on an automatic cause any damage to the engine?


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## nitestridar (Jun 29, 2002)

nissanracer805 said:


> *yo, wasup, had a question for ya'. does downshifting on an automatic cause any damage to the engine?  *



i dont think it does.... i drop it back into 2 if i am under 65mph and i want to get onto the pkwy.....i have been doing i for a while now and no problems yet....


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## Ninety-Nine SE-L (May 5, 2002)

I downshift all the time. I say it's safe to go down to 2nd gear ok and don't be scared to use the o/d button. Downshifting to first is kinda damaging and uncomfortable and you have to do it at a really low speed (under 2000rpms). If you continue, I recommend you get a tranny cooler to eliminate some of the extra heat that is being stressed on the trans.

It's a pretty good way to slow down or speed up it you downshift and floor it (get more top-end power), but don't forget that it's better to replace brake pads than a transmission.


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## Guest (Aug 13, 2002)

hey, thanks for the info guys, i've just never heard of downshifting an auto, just on a standard transmission, i've downshifted to 2nd on my auto a couple of times but wasnt too sure of the side effects, like if it might make the transmission wear out quicker or somethin'. anyways, thanks.


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## Overlooked (Jul 10, 2002)

Downshifting an automatic is bad. It's hard on the tranny & the shifter cable. I would not recommend doing it all the time.


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## JayL1967 (Apr 30, 2002)

How to use o/d button when u need more power?Is safe?

Jay L.


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## Guest (Aug 13, 2002)

Well, doesn't the automatic transmission "automatically" down shift when you push the pedal down?

Don't rev your engine on Neutral then shift to drive... it'll screw your transmission... and i wouldn't want that to happen.


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## JayL1967 (Apr 30, 2002)

Can some body explain to me when I have to use the o/d button and when I can downshift to 2?
TIA

Jay L.


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## nitestridar (Jun 29, 2002)

when i was looking over my owners manual it sounded to me like the were saying that i can put the car into 2nd anytime i am under 64 mph i beleive it was.. it never said anything about not shifting from drive to 2nd...it just said never go over 64 in 2nd


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## barnoun (May 7, 2002)

JayL1967 said:


> *Can some body explain to me when I have to use the o/d button and when I can downshift to 2?
> TIA
> 
> Jay L. *


Say you want to keep the rpms higher on the street for better acceleration, turn o/d off. If you're going up a hill and the car is in 4th and lagging bad, turn o/d off. If you're still going up the same hill, going less than 65mph and still lagging, put it in 2. Be creative


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## Ninety-Nine SE-L (May 5, 2002)

crzflip02 said:


> *Well, doesn't the automatic transmission "automatically" down shift when you push the pedal down?*


it does, but only to a certain extent. It decides on it and sometimes it will and sometimes it won't. when I want to reach into that top-end power, I downshift myself to be sure it'll be in the gear I want when I want.


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## JayL1967 (Apr 30, 2002)

BARNOUN
iS SAFE IF i DRIVE IN THE CITY WITH O/D OFF?

TIA

Jay L.


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## barnoun (May 7, 2002)

It's safe. I've driven in the city with o/d off since I got the car in '95. After 7 years, no problems, and I do 90% city driving. Only downside is a little lower fuel economy, but I can always turn it on if I want to save gas.


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## JayL1967 (Apr 30, 2002)

Thanks

Jay L.


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## HCS200sx97 (Jul 8, 2002)

Running with O/D off will never damage your tranny, unless its already got problems, but your gas milage will not be great. Also, downshifting from anything to "get more power" will fry an auto tranny. The tranny as not designed to engine brake or run at a higher RPM like you can with a manual.


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## nitestridar (Jun 29, 2002)

i knew nothing about overdrive and i turned it off one day and started driving i must of hit about 45-60 somewhere in between there...when i stopped at the light the car kept jerking and almost died....that was the last time i shut it off.....lol


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## barnoun (May 7, 2002)

selrider99 said:


> *i knew nothing about overdrive and i turned it off one day and started driving i must of hit about 45-60 somewhere in between there...when i stopped at the light the car kept jerking and almost died....that was the last time i shut it off.....lol *


That jerking can't really be only because you hit 60mph with o/d off...I mean, 3rd gear can go to top speed, and it does if you floor the pedal even with o/d on. Also, don't you think the nissan engineers would have not put an o/d button if it was too risky to use it.


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## omega (Jun 27, 2002)

hah, i used to have an 89 camaro I drove in overdrive all the time until I started shifting into drive to get my RPMs up higher for a nicer acceleration on my low end, needless to say my too fast driving and the fact I didn't take care of it killed it oh, and my girlfriend/friend, whatever she has an 86 Toyota Cressida, never drove it out of overdrive, so I decide to see what kindof condition it's in, as were driving down the highway I take it out, it freaked, she freaked, i turned it back on. it's good for fuel economy not for power, and vise versa for straight drive.


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## Guest (Aug 14, 2002)

so, why did the freakin' auto engineers put the 1-2-D-N-R-P
instead of just D-R-N-P..........lol.... i'm thinking you can downshift to 2nd gear without causing problems.......weird


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## rios (Jun 10, 2002)

they put that there in case you are climbing up steep inclines and stuff. its less strees if it is on a lower gear.


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## Guest (Aug 15, 2002)

so basically, u cant downshift from Drive to 2nd on an automatic since the tranny isnt designed to take that much stress? it must be safe to do it once in a while tho, not everytime u go out and drive.


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## barnoun (May 7, 2002)

The way I downshift is, I mash the pedal so the tranny downshifts on its own, and then I shift the lever to 2 after the gear change has already happened to reduce any possible stress. ..seems less stressful for the tranny that way...


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## nitestridar (Jun 29, 2002)

i only do it when i want to get on the hwy...


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## hard_charger (Jun 3, 2002)

*o/d explained*

straight from the horse's mouth: how o/d works in an automatic. this is taken from www.howstuffworks.com. for the rest of the article about auto transmissions, look at this. 


based on this, i really don't understand why some of you are having such problems with o/d off. it sounds more like a case of an improperly maintained transmission (are you getting it serviced every 25 to 30K miles?). anyhow, hope this helps...

Overdrive:
By definition, an overdrive has a faster output speed than input speed. It's a speed increase -- the opposite of a reduction. In this transmission, engaging the overdrive accomplishes two things at once. If you read How Torque Converters Work, you learned about lockup torque converters. In order to improve efficiency, some cars have a mechanism that locks up the torque converter so that the output of the engine goes straight to the transmission. 

In this transmission, when overdrive is engaged, a shaft that is attached to the housing of the torque converter (which is bolted to the flywheel of the engine) is connected by clutch to the planet carrier. The small sun gear freewheels, and the larger sun gear is held by the overdrive band. Nothing is connected to the turbine; the only input comes from the converter housing. Let's go back to our chart again, this time with the planet carrier for input, the sun gear fixed and the ring gear for output. 

Ratio = 1 / (1 + S/R) = 1 / ( 1 + 36/72) = 0.67:1

So the output spins once for every two-thirds of a rotation of the engine. If the engine is turning at 2000 rotations per minute (RPM), the output speed is 3000 RPM. This allows cars to drive at freeway speed while the engine speed stays nice and slow.


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## Ninety-Nine SE-L (May 5, 2002)

well, I'm glad we know the definition of overdrive, but this is really about whether our a/t's can handle the stress of us manually changing the gears.


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## hard_charger (Jun 3, 2002)

hey, i was just explaining it for the uniniated. besides, someone asked a question about the purpose of o/d (i think). got it?

as far as our automatic cars handling downshifting/upshifting. the answer is a qualified "yes." second gear is for better engine breaking on steep inclines (and for climbing them). as long as you're not downshifting at a ridiculously high speed (i.e. anything above 55 mph), the tranny can handle it. in fact, if you go to the article i linked, you can read more about how automatic transmissions actually work (fascinating, really). i wouldn't recommend a downshift to first unless at *very* low rpms. personally, i only shift into first at a stop. and, yes, manually shifting your car to redline through second gear will net you faster acceleration times because you stay in the engine's power curve longer ... blah ... blah ... blah

on the otherhand, i'm not certain all that much is to be gained from downshifting to second on a flat road unless you're banking on that red light turning green real quick-like. second gear will let you take it to the redline again (as long as you are in the appropriate gear) but starting in second doesn't do much for an automatic.

hey, like anything, the more you use/abuse the gears, the more likely the tranny will wear out. 'nuff said.


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## Psch91 (May 18, 2002)

Sorry about this being so off topic. But JayL1967, we can read your sceen name, you dont have to put Jay L. at the end of each of your posts, thanks.


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## hard_charger (Jun 3, 2002)

what gives psch91? the man wants to put his name in his post, so what? geez. let sleeping dogs lie.


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## JayL1967 (Apr 30, 2002)

Ok Psch91 no more Jay L.


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## Guest (Aug 28, 2002)

downshifting is fine, but just dont over do it. Remember its an automatic and was not designed for manual use. Transmission problems may arise from repeated down shifting!


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## nitestridar (Jun 29, 2002)

there is nothing better than ds a auto going onto the pkwy


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## Green_Lantern (Jun 6, 2002)

Downshifting from <D> to <2> or even to <1> is very useful when your driving down on a snowy hill. Also helps me with stopping during the snow so I won't be skidding and slipping all over the place.


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