Overdrive

[diablo5969]

I have a '94 Ex automatic, and I have a question about the overdrive. Whenever I drive it, I always just put it in overdrive because that's what I've always done, but whenever anyone else drives it, they always put it in drive. Wht's the difference? Who's right?

Thanks

 

[RTStork]

You should drive in overdrive unless you are pulling a heavy load or going up steep hills. Driving in regular drive just wastes gas and causes extra wear and tear on the motor because it runs at a higher RPM.

 

[JDraper]

RTStork's right. Use overdrive unless towing. The tranny will shift itself out of OD as it needs to under normal conditions. Better on gas mileage

 

[diablo5969]

Cool, thanks guys. I asked the guy at NAPA about it, and he said some cars have it the way you said, or some cars have it the opposite, and he didn't know about Explorers. Now another related question: if drive is for towing, what are the 1 and 2 gears for? Sorry about all the questions I should know the answer to, but thanks for the help.

 

[Byrd91]

1 and 2 simply limit the transmission to 1st gear and 2nd gear. Not for towing so much as offroad where you don't want your transmission shifting all the time. Some people have the conception that 2 actually starts in 2nd, but I don't think so, just goes from 1st to 2nd and stops at second. I could be wrong though.

 

[diablo5969]

Alright. Cool. Thanks!

 

[asp84]

Just backing up what everybody else has said.
Youre going to want to drive in Overdrive unless your towing. You'll find out really quick that 1 & 2 are not for driving.....For offroading or short high torque pulls. By the way, when you put the sjifter on 2nd, it starts in 1st gear, but limits itslef when it gets to second. It Does NOT start in second. (starting in second could kill the engine in an uphill situation or spin the torque converter)

 

[JDraper]

Originally posted by asp84
By the way, when you put the sjifter on 2nd, it starts in 1st gear, but limits itslef when it gets to second. It Does NOT start in second. (starting in second could kill the engine in an uphill situation or spin the torque converter)

Uh, my 01 does start in second if you put the shifter in second when you are at a stop. It's for use in low traction situations when you want less torque to limit wheel spin.

1 & 2 can also be used as a engine brake when towing large trailers. It's a little hard on the tranny, but so is towing. By downshifting, you use the engine compression to slow the vehicle. The tranny also has safeguards built in so that you can't overrev the motor by shifting down too soon. If you slap the shifter down to 1 at highway speed, it won't actually downshift into 1st gear until your speed is low enough that the tranny doesn't spew its parts under the truck.

 

[asp84]

When in second the 91-94 Explorers (I should of clarified that) Do start in first.

 

[Alec]

When the selector is in 2, my 96 sometimes starts in first, and sometimes in second. It depends on the road traction and level.

 

[LOGJOCKY]

When I went to the dealer he told me to use regular drive unless doing more than 75k. I also seen this on motoring 2001 on tv. Onthe show he said that in slow speeds it is not nessasary to use OD and that it is easier on the tranny to use regular drive. I have been doing this for a year now and i have no probs with it. I also have not lost any milage by doing it.

 

[Robert]

75K, what is that, about 47 MPH? If so, then of course you wouldn't see any reduction in mileage. You are also wasting your time since your transmission won't even shift into OD until you get between 45 & 50 MPH. It is possible that if you were right at the speed that would cause the transmission to shift into OD, that you would shift a few extra times as you speed up and slow down. It shouldn't be enough to worry about though since there is some histeresous (for lack of a better word) built into the shifting. For instance my '97 will only shift into OD once I have been driving at 50 MPH for 2 or 3 seconds at cruise (light on the gas). I have to slow down to less than 45 MPH before it shifts back into 4th gear or step on the gas hard enough to cause it to downshift (passing).

I drove for a couple of tanks with and without OD on my normal daily route. I did enable OD on the 5 mile stretch of my route that I drove 70 MPH though. I lost almost 2 MPG on the two tanks that I had OD off. If you are driving below 45 MPH, then it makes no difference whether or not you turn OD off, since your transmission won't shift into OD anyway. If you are driving above 45 MPH, you might as well leave it on since your engine will turn at a lower RPM which will save engine wear and increase gas mileage. All OD is is the top gear in your transmission. It would be no different than driving a 5-speed manual and not shifting into 5th gear until you got up to 45 MPH. Below 45 MPH, you shouldn't be in 5th anyway, above 45 MPH you should.

 

[01EB5.0]

I would just like to say that my 95 does start out in 2nd gear when you put it in 2. Same deal with my mom's 94 E150 van. It will feel like it shifts, but it is not, that is just the torque converter locking up.

 

[diablo5969]

So OD is for normal driving, drive is for towing, and 1 and 2 are for four-wheeling. So are 1 and 2 used as if it was a manual transmission in first and second gear? Are 1 and 2 used in conjunction with or instead of four wheel drive? How do they help with four wheeling? How do you know when to use 4x4 and when to use low range? What's the difference between everything?

 

[Alec]

Diablo, your tranny, the auto 4 speed:

1,2,D,OD = 1,2,3,4 like in a 4 speed manual (with 4th having a reduced ratio for hwy economy). OD is the normal everyday setting. I switch out of OD sometimes to engine brake, downshift for highway passing, or to keep the tranny from shifting a lot in high stress situations.

You'd put the selector in 1 or 2 for situations where you need low end power and engine braking (mountain driving), or offroading. Keeping the tranny in first while offroading will keep your revs up and make sure you have power when you need it, it will also help you idle over obstacles.

Use 4wd when offroading and you think you might lose traction or need the additional pull of the front wheels to get over something.

4 wheel low adds added reduction to the gearing, giving you more power, usually about 4:1. In 4w hi, the transfer case has a 1:1 ratio (the tranny and your rearend then determine the driveline ratio). You basically use 4w-lo for rock crawling.

does that help?

 

[Robert]

4:1, I wish That would make for some awsome gear reduction. It is more like 2.67:1. Anyway, to add to what Alec said, it is sometimes helpful using 2 to get started when you are on ice or snow. It reduces the torque to the rear wheels when you start off which will help prevent the rear tires from slipping when you start off. Out of my '92, '94, '97 Dodge Caravan, '93 Mercury Sable, '95 T-bird, '97 Explorer & '95 Chevy Astro, only the Astro would start off in 1st gear when the selector was in 2. All putting it in 2 did was held the transmission from shifting beyond 2nd. All of my other vehicles all start off in 2nd gear when the selector is put in 2 (with the exception of my Explorer which actually starts off in 3rd when you put it in 2).

 

[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.

 

[diablo5969]

Cool. Thanks. Now I understand what it's all for. But one more question. If 1, 2, D, and OD are like 1, 2, 3, and 4 in a manual transmission, is it possible to use those gears as if using a manual (like people would for drag racing, for exaple) or would that totally kill the transmission due to the fact that there is no clutch?

 

[diablo5969]

So wait. Now that adds some confusion from Byrd91. So you should leave it in D all the time except for highway? Or you should leave it in OD all the time except for towing? Ahhh! Very confusing

 

[Alec]

1) yes, you can manually shift the tranny, but you don't really need to. Sometimes I manually drop a gear when making a steep descent.

2) mostly leave it in OD.