this is not technical, but i need someone to tell me what overdrive is. i think it is when the car just automatically goes into 5th gear. it's an AUTOMATIC, so DUH, huh? if i am out of over drive the car works through the gears...still automoatically. it never goes past 45 in over drive. i use it around town usually to save gas, but was on the highway today. boy did a lot of people pass me.............

thank you!

 

Overdrive simply means the ratio of GEARBOX input to output is a certain way, ie there is less rotation from engine going in than there is coming out and it is termed overdriven, most 5 speed gearboxes are 1:1 in 4th so same in and out speed of gearbox, but 5th gear is an overdrive so more speed coming out of gearbox than going in.
I get the impression this is NOT what you were after but answers the question as to what overdrive is.
As we are talking automatic boxes the same applies, as regards engine speed in and out of the gearbox.
Overdrive will NOT select or go IN below a certain speed as the car simply won't have the power to pull the high gearing in an automatic even with the torque convertor.
I get the impression from your description you are getting SLIP in overdrive, if it won't go over 45, it needs looking at, may just be low on TRANS fluid, ATF, so worth checking this first.
Any decent auto trans specialist can tell you what is wrong by driving the car.
tabetha

 

Thank you!

I was driving in overdrive becasue of snow/ice and "crap from the sky" to avoid going too fast/slipping, and all that jazz.

It should not go into 5th from OD, from what I am understanding...is that correct? I heard it also saves on gas around town in low speeds.

Thanks!

Sophie

 

OD will be the HIGHEST GEAR, you have, OD will NOT function at low speeds.
As to whether it will go into 5th from OD, I don't know as each box manufacturer is different, and is likely to be ecu controlled as well, so depends on programming but OD will on all auto's be the highest possible gear, I would switch out OD in town as it creates extra work and wear in the box, and will NOT improve MPG as more slippage will be needed, which is odd as OD is always a TORQUE CONVERTOR LOCKED GEAR, anyway.
tabetha

 

maybe i didn't start the question out right or maybe i just don't get it. i have a knob that when i push it in it staked OD off. i usually use OD but was told that it would be good to take it off (punch the button it so it says "O/D OFF" on the dash light) when I am around town and just driving in low gears--for example, i live near some hills, and when there is snow and/or ice around them i select and use second gear to go up them. if i just go up them it can be quite tricky.....i use this the most in snow conditions.

thank you again!

 

That's a bit simpler!!
Yes most people do select OD OFF when in town, though the box will do this anyway, not really any need, I find it more useful when overtaking as kickdown can be slowed by OD ON.
tabetha

 

By George, I think I have it!

Thank you for your help!

Sophie

 

No probs sophie, glad to help.
tabetha