Question about Overdrive?

[XerOne]

ok, I was wondering while having OD on if it saves gas mileage? My reasoning is because when I turn it on my rpm's go down and I have a smoother ride when i'm not touching the gas pedal, meaning that the pathy glides farther, when I turn it off my rpm's go up and its like I put the brakes on slightly, but enough to notice, and this is noticable from 20mph to 100mph . Thanks this is on a '95 se 4x4 w/auto obviously

[MaritimeMan]

I'm sure someone will correct me if I'm wrong, but the OD is also refered to as the Lock-up function of the tranny. What it is doing is creating a solid mechanical link between your engine and the tranny, rather than the fluid link in your torque converter. Due to losses in the fluid transfer of power, the lock up eliminates this, and is the result of the "loss of power" you feel when taken off. It has definate advantages, but some disadvantages as well when climbing hills and such. As far as leaving it on, duno, I have a manual tranny heh.

[88pathoffroad]

You're right, XerOne. The OD should normally be left on for best gas mileage.

[XerOne]

cool, thanks

[94extreme]

it's not really an OD. after engaging the button the computer shifts the tranny at different points. that's all...

Edited January 16, 2005 by mzxtreme

[Airrun2002]

The overdrive actually loses power when on but saves gas milage ei, turn overdrive of when in hilly places or mountains and also when towing. if you tow in od then you take the chance of burning up your tranny. And on hills it actually saves milage to have it off cuz it runs at a steadt 3500rpm rather than kicking down gears and revving whenever you hit a hill. my 2c.

[Greenbushy]

Od is overdrive, it is a ratio in the transmission that is taller than the 3rd gears 1/1 ratio, so just look at overdrive as being 4th gear. Lockup is the torque convertor locking up, ie: the convertor becomes a direct drive unit with no slippage just like the clutch on a manual vehicle. Lockup is thought to be related to overdrive by many owners but its not directly a part of overdrive, the torque convertor can accutualy be locked up in 3rd or 2nd gear as well (Not 1st or reverse without valve body modifacation on pre 95 Pathfinder/terranos) I posted this easy mod i while back on this forum for anyone interested. Advantages of locking up the convertor in mainly 3rd gear as i do is when cruising thru back roads etc at speeds that are to low for overdrive.

The reason i say speed to low for overdrive is because you sholuldnt drive around at lower speeds in overdrive, its just the same as driving a manual vehicle around in top gear at low speeds and you notice how jerky it can be, same thing is happening with a auto you may not notice it because the convertor is taking most of the shock out but the transmission certainly is noticing it and will let you know when it fails at a lower milage. Greenbushy

[GrimGreg]

All the button does is allow the tranny to shift into 4th gear (OD). If the button is switched off the tranny will only use 1st 2nd and 3rd gears. Unlike most American cars that have a seperate shifter position for OD, if you drive with the shifter in OD all the time on those, it will destroy their trannys.