To Overdrive, or not to Overdrive?
 

When is it appropriate to put your car into overdrive. I've heard it was best to do it on the highway to save gas. It seems that it doesn't rev as high when it is engaged - like 2500rpm @ 60-70mph. But when i'm crusing at those speeds with it off it seems to be upwards of a little over 3000rpm. Makes me wonder if it should be up that high.

Any comments?

1995 GLE(261000 km)

you do know that then u press the button it actually turns overdrive off right?

is this a serious thread?

yes it is a serious thread...i've never owned a car with it before so i would like to know. And yes i know that when the light is on, the OD is off...i'm just curious by's

Haha wow...

Overdrive is 4th gear...when you turn it off, you stay in 3rd gear.......

Your car has four gears; Overdrive is 4th gear. It's the highest gear.

Of course, at a given speed, higher gear = lower engine RPM = less fuel consumption.

You should keep OD off if you're driving around town and don't plan on going above 40-50mph, and don't want it to keep shifting back and forth between 3rd and 4th gear.

If you're going to be going above 50, then you should turn it on.

If you've owned an automatic that was made in the last twenty years, it has probably had overdrive; some cars are just more explicit about how to turn it on/off. All overdrive is is the highest gear in an automatic transmission that it automatically switches to at cruising speeds. Asking whether you should use it or not is like having a standard and asking if you should use fifth gear or not (or sixth).

Unless you're at the strip, keep overdrive on.

thank you, this is all i was looking for.
Whne i plled my codes from the computer one was 1106 - AT 4th gear signal fault? But it works just fine...

nalc is almost right. the owner's manual says that od off is for climbing hills, towing etc. if you drive around town about 25mph it won't go into overdrive anyways - there's no 3rd-4th shifting.

ohh...i tend to drive around with it off when inthe city just cause of the more peppiness...but when i get up to about 60 or 70mph, I flick on the OD, it "shifts into 4th" and the rpms drop. It's a loud car when the rpms go over the 3000 mark

Guys, overdrive is not really a gear. There are 4 different speeds, but when in overdrive, it's simply the torque convertor locking. Feels and looks like another gear shift...but it really isn't.

S

torque converter locking?

OD == 4th gear. You say there are 4 gears, but OD is just the TCC locking up?

Anyway, 4th is a seperate gear. You can be in 4th with or without the TCC locked.

thank you... :fro:

^ What he said. The term "overdrive" refers to a gear that has LESS than 1.00:1 ratio. That being said, it's possible to have more than one overdrive gear and therefore overdrive isn't simply the highest gear in a set.

D'oh, I failed. Yes there are 4 seperate gears. What I meant is to achieve overdrive, it's 4th gear with TC lock up to achieve it. Is it not correct for this trans? I know it's true for many other transmissions. Let me know, because if that isn't, I retract what I said. :)

S

No, TCC lockup has nothing to do with the existence of 4th gear in the RE4F04?. Most of the time when you're driving steady in 4th, the TCC will lock, but you can easily drive around in 4th/no TCC lockup. 4th has an overdrive gear ratio regardless of lockup.

Um sort of but not quite. Overdrive is a gear ratio greater then 1 to 1.
Fourth gear in our auto trannys is an overdirve gear.
The fact that the TC locks up doesn't really change gearing ratios, although it seems that way.

OD OFF in our cars keeps the tranny from shifting into 4th gear and also doesn't allow the TC to lock up. Thus the gear ratio never gets to an overdrive condition.

Common misconception is that Overdrive turns off/on the final gear of hte gearbox, which is false.
Overdrive is an OUTPUT gear ratio.
"a gear assembly which produces more shaft revolution than that transmitted to it".
Meaning the flywheel/gearbox makes 1 RPM, it outputs 1.5+ RPM.

Listen to/feel your auto shift as you drive. The dash won't show any light, but the computer will engage and disengage OverDrive between shifts as it see's fit when you drive certain behaviours.

:squint: