# OverDrive



## kahoots (Aug 25, 2003)

today i got into an argument over what overdrive does. does any1 know what overdrive is used for and how does it make the engine run differently. thanks


----------



## Sethticlees (May 30, 2002)

Overdrive saves gas! 
Like the equivalent of the 6th speed in a manual trans. 
It's gear ratio is so high that every 1 rotation of the crank (or better .92) outputs one rotation to the drive tran. 

Gear ratio
1st...2.861
2nd..1.562
3rd...1.000 (1:1)
4th...0.697 (OD)


Overdrive is most useful at high speeds on the freeway, ~60+ MPH.


----------



## Gsolo (Sep 11, 2003)

ok, overdrive use to be like a taller ratio of a gear. can't describe it very well. but in todays' terms an overdrive is just a gear that is taller than a 1:1 ratio. like say on a 5 speed....4th gear is direct ( 1:1ratio) and 5th is overdrive (.92:1). auto's are the same way if they have overdrive. the purpose of it is just to save gas at freeway speeds cause it lowers your engine rpm for the road speed


----------



## kahoots (Aug 25, 2003)

what is the point of having overdrive off then?


----------



## Felonious Cat Stalker (May 1, 2002)

With an automatic transmission, you should switch the overdrive to off if you are driving in stop & go traffic and in town. This reduces the amount of shifting the transmission does and will greatly extend the life of the tranny.


----------



## Boromir (Oct 13, 2002)

its also good for going up a steep hill or road.


----------



## Gsolo (Sep 11, 2003)

Boromir said:


> *its also good for going up a steep hill or road. *


umm....overdrive isn't for steep hills


----------



## chimmike (Oct 17, 2002)

kahoots said:


> *today i got into an argument over what overdrive does. does any1 know what overdrive is used for and how does it make the engine run differently. thanks *



engine doesn't run any differently than it normally does.

Overdrive is basically an extra gear to run at lower rpm and therefore save gas.


----------



## chimmike (Oct 17, 2002)

Boromir said:


> *its also good for going up a steep hill or road. *



WRONG!


----------



## niky (Jul 20, 2002)

what he meant is having it off is also good for going up a steep hill or road...


----------



## Gsolo (Sep 11, 2003)

i wondered if thats what he meant. but most newer automatics wont shift into over going up a hill cause the load on the engine tells it that its working to hard to pull into overdrive.


----------



## kahoots (Aug 25, 2003)

do ypu get more power when overdrive is off?


----------



## chimmike (Oct 17, 2002)

kahoots said:


> *do ypu get more power when overdrive is off? *



I guess you could say that...........basically it's a lower gear so the rpm runs higher, more in the power band.


----------



## wwmjax (Mar 24, 2003)

overdrive is the highest gear the vehicle has..... when you turn it off.... it puts it in a lower gear so you can have more torque for towin shit


----------



## niky (Jul 20, 2002)

Not only, that, when going up- or downhill, having OD off locks the converter more aggressively, giving you some extra traction / engine braking...


----------



## LethalAudio (Feb 12, 2003)

Tell me this, I can turn my O/D on and off when Im stop and go traffic, I cant tell any difference between the off and on setting, is there a difference at low speeds or is it just something that is noticable around the mid range or something?


----------



## wwmjax (Mar 24, 2003)

like i said... its the highest gear... so your not gonna notice until your in the last gear..... so to answer your question..... mid range


----------



## James (Apr 29, 2002)

LethalAudio said:


> *Tell me this, I can turn my O/D on and off when Im stop and go traffic, I cant tell any difference between the off and on setting, is there a difference at low speeds or is it just something that is noticable around the mid range or something? *


that is because OD does nothing in S+G traffic, most autos with the OD on will just try to shift as fast as it can to the OD gear so you save gas... you still have all the gears but the tranny will want to shift out of the lower gears faster making your car slower....


----------



## Boromir (Oct 13, 2002)

LOL what i meant is when im going uphill my car feels heavy and not going nowhere. i push the OD OFF and runs better. correct me if im wrong


----------



## Gsolo (Sep 11, 2003)

Boromir said:


> *LOL what i meant is when im going uphill my car feels heavy and not going nowhere. i push the OD OFF and runs better. correct me if im wrong  *


thats cause it downshifts again when you turn od off


----------



## James (Apr 29, 2002)

ya that is what I'm saying, you have the OD on its trying to climb a hill in top gear... if you mash your foot on the gas it will downshift which is basically what it will also do if you turn off the OD as previously said above.


----------



## Gsolo (Sep 11, 2003)

James said:


> *ya that is what I'm saying, you have the OD on its trying to climb a hill in top gear... if you mash your foot on the gas it will downshift which is basically what it will also do if you turn off the OD as previously said above. *


except that on newer cars having the od on or off changes the personality of how and when it shifts and torque converter lockup.


----------



## niky (Jul 20, 2002)

exactly... OD OFF makes it shift a little more aggressively (well, it feels like it...)... plus, keeping you out of 4th gear effectively prevents it from free wheeling... so when you take your foot off the gas in 3rd, you get some engine braking...


----------



## Gsolo (Sep 11, 2003)

niky said:


> *exactly... OD OFF makes it shift a little more aggressively (well, it feels like it...)... plus, keeping you out of 4th gear effectively prevents it from free wheeling... so when you take your foot off the gas in 3rd, you get some engine braking... *


but if you're like me and hate autos....i just shift autos like a manual. i even catch myself using my left foot sometimes in automatics  accidentaly turned my brights on once doing it at night (older cars have brights button on floor)


----------



## wwmjax (Mar 24, 2003)

i just throw my car in 5th gear


----------



## niky (Jul 20, 2002)

haha... WTF... left feet? at one time we had both an A/T and an M/T Sentra... they were the same year model. Every time I got in the A/T Sentra, I was thrashing my left foot in the wheel well on every shift; and every time I got in the M/T Sentra, I was grinding the gears... go figure.


----------



## sentra_hilo (Apr 23, 2003)

so its better for the car if you have it off in daily driving? crap the orange light is irritating.


----------



## niky (Jul 20, 2002)

It does change the car's behavior... when you're off the gas, the car basically stays in overdrive (coasting) till you gas it again... with OD off, it engine-brakes in third...

But no, it's not better to drive with OD off... just turn it off when you're in a hilly area.


----------



## LethalAudio (Feb 12, 2003)

you know, for something so simple, o/d certainly does cause alot of confusion. lol


----------



## Gsolo (Sep 11, 2003)

LethalAudio said:


> *you know, for something so simple, o/d certainly does cause alot of confusion. lol *


simple??? automatic transmissions are one of the most complicated mechanisms in the world.


----------



## niky (Jul 20, 2002)

not as complicated as CVT...


----------



## James (Apr 29, 2002)

what else is there to talk about? its not rocket science, if you are still confused you should not be touching your car anymore.


----------



## niky (Jul 20, 2002)

I'm confused... is the big red R on my shifter the rocket boost?


----------



## James (Apr 29, 2002)

Yes it is Niky, you should use it more often...


----------



## Gsolo (Sep 11, 2003)

zAoemaster said:


> *we arent talking about the automatic transmition... we are talking about overdrive...pay attenetion *



huh what...i fell asleep what we're we talking about. and yah i know i just felt like saying something. and yes the big red R means rocket power...used best at freeway speeds


----------

