Do you drive your max with overdrive on/off for regular driving and/or legal racing? I seen to get more power with it off but put it on when i go on the highway to reduce the rpms. Is this right? Does it affect mpg at all?

 

Of course it affects MPG. I leave it on 99.998% of the time.


Having it off has an affect on RPM's dropping slightly ~ 3.8k.

I only dyno with it off, typically.

 

you dont get more power. you just take longer to shift. o/d off under 40mph in stop and go traffic helps prolong tranny life (reduces the amount of shifts). o/d on on the highway saves on tranny life and mileage. for racing it is better to drive with it off although i would prob shift myself (not that i would race an auto max).

 

In 1st or 2nd it wont matter if the OD is on or off, 3rd is where it actually affects performance.

http://forums.maxima.org/showthread....rd#post3946213

 

so basically it's a good idea to drive with OD off when you're in city traffic barely doing 35-40mi, right? The only thing OD OFF does (in maximas anyway) is lock out the 4th grear to reduce needless 3-4 shifting? Does this affect the tranny negatively in anyway like overheating? Cause it drives me nuts when i'm doing 35 and the tranny shifts from 3rd to 4th @ 1700rpm and then has to downshift back to 3rd if i need to accelerate (cause it's too low in the powerband)

 

i wouldn't turn it off. unless your looking for performance purposes you should just leave it on at all times. having it off while your driving on city streets just to gain more power is a little absurd. i would take higher MPG over that minimal power gain any day.

 

i'm not turning it off for power purposes! I do it to stop raping my 3-4th shift.

 

Going light on the throttle solves that issue

 

ANYWHOOOOOO, my question is: Does OD OFF just disable the 4th gear and doesn't overheat the tranny if i'm only doing 35?

 

from my understanding its purpose is not to only prevent shifting into fourth gear, but it affects all gears. it will not prevent overheating by preventing shifting, but will prevent damage that occurs during shifts.

 

Just leave it on unless you are in traffic ... done deal. /thread

 

Thank You, 2da mizzax and scrhale; That's all i needed to hear

 

How? . . . .

Onc again, I ask...How? . . . .

 

I doesn't affect all gears. It just disables the car from shifting to 4th. The "damage" he is referring to is just the normal wear and tear the car takes from simply shifting. Of course there is virtually none because 3-4 is a much smaller shift compared to 1-2 or 2-3.

 

It does affect 3rd gear though.

 

yeah, so unless i'm doing 40+ mi/h i really shouldn't need the 4th, Cause if i'm doing 35 my rpms are about 1500 (which is fine, no need for 4th gear). It just that if i'm barely applying the throttle doing 35 in city traffic, the 3-4th shift occurs @ 1700rpm, once it switches to 4th, i'm down to ~1300rpm where the shift seems to always jerk. But if i'm on a vacant road with no one in front of me(or where evryone's speeding) the 3rd-4th shift occurs @ 2Krpm where it's nice and unnoticable.

 

fixed...........

 

Yes you are fine. I regularly turn the OD off for that very reason. It hurts nothing. In fact it eliminates the lugging it will do before it downshifts out of 4th.

 

scratch what i said before, i guess it doesnt matter. but since i found it interesting i searched and hears what i found:

"A car uses overdrive when it is traveling at high speed over long distances. Overdrive, or cruising gear, is a device which enables the engine to run at a relatively low speed even when the vehicle is traveling fast......The driver used first gear for starting and changes to second and third gears as the car gains speed. Finally in top or fourth gear the engine speed is transmitted unreduced through the gearbox. In overdrive a large gear wheel drives a smaller gear wheel on the propeller shaft. This shaft then rotates faster than the engine, thus reducing wear and tear and saving petrol(gas)."

but still, the wear and tear isnt very much if O/D is on.

 

that's what i do, and i'm gonna continue to do it

 

Uh except for the high speed over long distances, what ur quoting is basically the definition of what gears do.....and the part about engine speed not being reduced in 4th gear isn't even true....
http://www.infinitihelp.com/Infiniti...ifications.htm
4th gear ratio is .694 and the final drive is 3.789. .694X3.789=2.63
besides, if engine speed isn't reduced at all, at 3000rpm i'd be doing 220mph on 205/65r15 tires. its really about 87mph baised on real life test
http://www.discounttire.com/dtcs/infoTireMath.dos
check yourself if you don't belive me. 3rd gear ratio is usually 1:1 before final drive btw

 

omg... its like a ****en 4th gear... geez.... if ur doing a bunch of hill driving and ur in traffic turn it off.... it better for the trans to stay locked in third rather than keep changing from 3rd to 4th...

try turning it off and go drive to 80mph see what happens

 

yea actually i didnt even think about that when i read it (the unreduced thing). i was mainly posting that for the first and last 2 sentances. but 4th gear deffinatly is reduced. cause in most(if not all) 4speeds, 3rd gear has 1:1 ratio.

 

doublepost sorry.

 

Actually, in the context of the of that quote you had, reduced means output rpm is lower than input rpm. In that context, 4th gear does not reduce, rather it increases. But the final drive reduces more that the 4th gear increases so the overall result is the wheel spinning slower that the engine.

 

hahahahaha

 

i was too wondering this and i looked it up in the book. i wouldn't play around with it like it's nothing because im like 80% sure i read something like "do not exceed 40 mph for extended periods when overdrive is turned off" just my 2 cents of tranny safety.

 

I dyno with my O/D OFF, and see 130 +mph in 3rd. .. .

 

uh 130mph in 3rd is like 7500rpm.... red zone

 

so for city driving, turn the o/d off.

highway, turn the o/d on.

right???

 

i leave it on half way

 

try it and see for urself....

 

TO: dannydarkman, YES, but only if you're doing no more than 40mi/h