Overdrive

[Byrd91]

Diablo, sorry for the confusion but heres what I do and my mechanic advises. I leave it in D all the time except when I get to speeds where I can comfortably stay in OD without all kinds of shifting. For me this is about 50 because I have 3.73s and for my dad it is about 65 because he has 3.27s. This doesn't hurt mileage because you let it shift when speeds are high enough and it saves the tranny because its not always shifting into and out of OD when you coast and then get back off the gas. If you have the push botton OD off then I would suggest keeping it off until you are up to speed. If you have to use the lever (91-94) its a bit more of a pain, but I still do it to save the tranny some work. If you look on older threads the majority of people use OD only at highway speeds.

As to the other question I don't think it wouldn't kill the transmission, but it would really be benificial either, because it doesn't always necessarily shift when you want it to. I think you would have better luck shifting with the throttle, like if you are racing just stay in the gas and when you want to shift, back off a little and it'll shift, then get back in it in the next gear.

 

[diablo5969]

Alright, cool. So all the information I have gathered is:

OD is for normal driving.
D is for towing.
2 is for four wheeling, or mountain driving.
1 is for four wheeling.

4x4 is for four wheeling.
Low Range is for rockcrawling.

Now I know that's just the overly broad idea of each one, and things get a lot more specific, but for a general idea, is that correct?

 

[Byrd91]

I would still suggest using D for driving around town at speeds under about 45.

 

[diablo5969]

And then do you just like switch it into OD while on the entrance ramp to a highway? Can it take the switch while doing that accelerating?

 

[01EB5.0]

This is getting too confusing. to make it easy just stay in OD unless towing heavy loads or driving in mountains. The transmission is made to be used in overdrive for normal driving. SOme say it will cause it to fail sooner, but so will neglect. If you regularly change your oil and filter in the tranny I would want to bet that it will last just as long as the guy who is switching in and out of D. Personally I use mine in OD for everything. I change my oil every 25,000 if i use regular oil and every 50,000 using synthetic. I replace the filter every 50,000. my transmission was replaced at 91,000 BUT it was not an overdrive issue...it was 2nd and 3rd gear! I carry heavy loads sometimes and tow also. i just leave it in OD unless I notice it is shifting between OD and D often. you can tell by the RPM needle raising and dropping with each small hill or whatever. The trailer I towed was an enclosed 5X8 loaded to the roof with camping equipment. I had the truck in OD the whole trip. it wasn;t shifting often or lugging. Personally I think it isn't necessary to put it in D for city driving the truck won;t go into overdrive anyways at those low speeds. The transmission is computer controlled and knows when it is ready to go into overdrive, so i just let it do as it feels necessary. The only time I drove without overdrive is off raoding on the sand dunes when I am in 4WD LOW, but still need higher speeds (30MPH) If you put it in 2 or 1 in 4WD low you won't be able to go very fast at all. In terms of when to use your 4X4 system this is what I think: Use 4WD High (4X4) in snow/ice or in other limited traction areas (mud etc..) I would not use it on pavement that was only rained on or on dirt roads that are hardpacked dirt. i would only use it when you need to. As for 4WD LOW, I would use that on sand or in low speed deep snow situations. You can't drive over 30 MPH or so when you are in 4WD LOW because your engine will be spinning pretty quick by the time you get to 30MPH.

ANyway enough rambling, basically what I think (and have been told by my Dad who is very knowledgable about vehicle systems) is drive in OD unless you notice it shifting often. OD is there for a reason...use it!

If you have any other questions, let me know. I'd be happy to help!

P.S.: Another way to make your transmission last longer is a transmission oil cooler (if you already don;t have one)
See ya

 

[Byrd91]

95,
You are right in everything you said except that the tranny won't shift into OD at low speeds (at least up through 96). On both my dads explorer and mine you will notice a difference when driving in town if you leave it in regular drive, you don't feel the extra shift. I agree that changing the oil is also a large contributor to transmission life, and maybe ford has wisened up some with the overdrive on the later explorers. I have heard awful things about the OD unit on explorers previous to 96 being weak and wearing out from overshifting.

diablo,
I usually shift it before the tranny actually would. Meaning I don't drive it to redline and then let it shift. Usually I'll just shift whenever I know I'll be getting up to speed in a while.

 

[Robert]

Byrd91 - That extra shift you feel when in OD is your torque converter locking and unlocking. When you are in D, the torque converter locks up earlier and stays locked up later. When you are in OD, your torque converter unlocks a lot easier which is a main reason for taking it out of OD when towing. When your torque converter is unlocked, it is generating heat by slipping. A heavy load will cause it more often than is good for the transmission. For around town driving, it is minimal and oftentimes non-existant. I'll monitor my shift transmission shift solenoids while coasting down from 45 MPH tomorrow and see if my transmission is actually going into OD. I will be surprised if it does. Even if it does, the shifts would not be while under a heavy load and should have no affect on the long-term reliability of the transmission. I have almost 81K hard miles on mine and it still shifts like new.

 

[01EB5.0]

My truck will drop into overdrive at 45mph coasting down a hill, but it'll normally stay there even when I put light pressure on the gas. after about 48 or 50MPH you can start to lay into the gas more and it'll stay in overdrive for me with an empty truck. Other trucks I drove took till 55 to go into overdrive..it depends on axle.

WHen I accelerate normally (about 2,250 RPM) in OD I feel first gear, 2nd gear, then at about 35MPH the RPM drops to about 1,750 and then at 50 MPH (2,250 rpm) it'll drop once more to about 1,750 RPM and that'll be the last shift. At 35MPH I thik it goes into third and locks up the torque converter at the same time. Does this sound correct? Why else would it drop so much more then first and second? Everything here is approximent. at 55MMPH I usually am doing a bit under 2,000 RPM and at 75 MPH I am normally a bit over 2,500 to give you guys an idea.

 

[Robert]

It should go into OD when coasting downhill at 45 MPH. That is about the speed that it shifts into OD. Mine does it around 50 MPH, but that is partly due to the larger tires. With my stock tires it was closer to 45 MPH. It shifts based on RPMs. At 50 MPH with my taller tires, my RPMs are about where they were at 45 MPH with my stock tires. The reason your RPMs don't react the same when going from 3rd to 4th as they do when going from 1st to 2nd is because your gears are not spaced evenly apart. You should drive one with a 5-speed auto to really experience it. My '97 shifts to 2nd at about 10 MPH, 3rd at 15 MPH, 4th at 30 MPH, 5th at 50 MPH when going easy on the throttle. Full throttle shifts are around 50 MPH, 65 MPH, 90 MPH. After that I have no idea where it would shift into 5th at full throttle.

Shortly after your transmission shifts into 4th, you will see your tachometer drop a few hundred RPMs as your torque converter locks. A lot of people mistake this as a shift. As soon as you apply pressure to your gas pedal, your torque converter will unlock again which will cause your RPMs to go back up. Press a little harder and it will downshift.

 

[01EB5.0]

Thanks for all the info Robert! i was just wondering something. You said you got nrw tires too, but i experianced the opposite that you did. SInce i got my bigger tires, my engine has shifted at lower road speeds and cruising my RPM's are lower compared to the old tires. my old were P235/75R15 and the new are P265/70R16. I changed the speedo gear and now I get better gas milage then i used to and the engine spins less, while still going the same speed. Did you notice that also?

 

[diablo5969]

Conversation is progressing on. I'm just going to take my info and step out. Thanks guys!

 

[Robert]

Originally posted by 95XLT
Thanks for all the info Robert! i was just wondering something. You said you got nrw tires too, but i experianced the opposite that you did. SInce i got my bigger tires, my engine has shifted at lower road speeds and cruising my RPM's are lower compared to the old tires. my old were P235/75R15 and the new are P265/70R16. I changed the speedo gear and now I get better gas milage then i used to and the engine spins less, while still going the same speed. Did you notice that also?

Yes for everything but the shifting. Mine used to shift into OD at 45 MPH with my stock tires. With my taller tires, it now shifts at 50 MPH. You should either be shifting at the same RPM or MPH, depending on how your computer controls your transmission. Mine seems to be more of a matter of RPM since mine now shifts at a faster speed.

 

[01EB5.0]

Hmmm...I wonder if in 97 they changed the system or something or if i just didn't really pay close attention to when it shifted before....

 

[Robert]

Originally posted by Byrd91
Robert,

Actually the transmission does shift into over drive at speeds below 50MPH. Everytime you let off the gas like when going down a hill or coasting through town it shifts into OD. This is why many people have problems with transmissions, they leave it in OD for all driving except towing and this causes a lot of unnecessary shifting in the transmission and the exceptionally weak OD takes most of the abuse and leads to most transmission failing. On a thread a while ago people who used D instead of OD for all driving except highway experienced about twice the transmission life as those who just used OD all the time. Even more so with high gears like 3.27s in the rear end.

OK, I checked out my transmission with my scanner on the way home from work tonight. I can say without a doubt the '97 5-speed automatic does not go into OD when coasting. There are three shift solenoids in the transmission. The operation is as follows:

1st A=on, B=off, C=off
2nd A=on, B=off, C=on
3rd A=on, B=on, C=off
4th A=off, B=off, C=off
5th A=off, B=off, C= on

When accelerating light to moderately my transmission shifts into 5th at 47 MPH via solenoid C turning on. If I drive at a constant speed of 50 MPH with my OD on and then let off the gas, my transmission shifts back into 4th via solenoid C turning off at 44 MPH and stays off until coming to a complete stop. There is also a "Coast Clutch" solenoid display on my scanner, but apparantly the 5-speed automatic doesn't use it since I never did observe it turn on. I have a feeling that if that solenoid was turned on it would feel like I was free-wheeling. Probably like the late '90s Tauruses that I have rented (very annoying).

 

[01EB5.0]

Ok, while were talking about trannies and free wheeling and all that I had a question. SInce my new tranny was installed if I accelerate fairly briskly, then let off the gas all at once and coast, the RPM will drop, then drop again, then it will dive down all the way to like 500 RPM or lower, then the RPM bumps back to normal idle speed. This is all while coasting. is that the free wheel thing totally disconnecting the transmission from the engine?

 

[Byrd91]

Robert,
I guess you really did some research. This is good info. I was going on info that I had read in older threads and my personal experience. With my dads 3.27s he has a hard time keeping it in overdrive and gets a lot of shifting. Hope this helps out everyone who has this question.

 

[Robert]

95XLT -- Mine doesn't quite behave like that. If I floor it from a stop and then suddenly lift off, my idle will drop down to about 2000 RPM and then slowly fall to about 1400 RPM unless I let my Explorer coast long enough that it would be at a lower RPM than 1400 RPM. Make sense? I didn't think so, so let me try it again. If I let off suddenly like I said, my idle will drop fairly quickly to 1400 RPM. Once I have coasted to a slow enough speed the RPM will slowly start going down from 1400 RPM all the way down to 600 RPM if I coast long enough.

 

[01EB5.0]

I wonder if it is normal for mine. one time as the RPMs were falling quickly, the engine almost stalled, but it didn't. I didn;t really notice this before the new tranny, but oh well...maybe it's normal

 

[FordExplorer18]

Im my opinion it would go like this.

1-2 For off roading.
D for regualy city driving.
OD for highway.