O/D On or Off?

[Jmeyers]

Can some one explain to me why I would want to O/D on or off while I'm towing my boat? I've heard a mix of different things but not from really reliable sources. Just wondering what the benefits of having it on may be?

Thanks ahead of time!

[Ryan_V]

If your vehicle is shifting in and out od, its hard on the tranny.

[S.D. Ice Angular]

Always use O/D "Off" when towing!!!!

Unless you have something like a F350 or 3500 truck.

[Esox_Magnum]

I use the tow/haul setting and run in OD as long as I'm not shifting up and down alot...alot depends on the boat and towing rig... Mines an 01 GMC 1/2 ton 4x4 pulling a 17' glass deep v...

[remington 300]

what ryan_v said,if it shifting in and out of O/D switch it, my ford can tow a619 ranger in O/d on most roads, unless it to much incline,but i can tow most times in O.d.

mike,

[Loon]

The increased fuel economy of O/D doesn't outweigh the cost of a new transmission...even at $4/gallon.

[Powerstroke]

On automatic trannys the tranny shifts between gears by "slipping" from gear to gear. Its a controlled movement that provides the smooth easy shifting you get in an automatic.

Your overdrive gear is a high gear that gets you the best gas mileage, but it down't have a ton of power at the gear. When you are towing something, especially something that creates a lot of air drag or is very heavy, it strains that top gear on the tranny and it trys to shift down for more power to keep your rig up to speed.

If your truck keeps shifting back and forth between gears, it builds up heat and too much heat caused by the "slipping" will cause problems with your tranny.

PUtting your truck in OD off will lock your truck out of overdrive to avoid the extra tranny shifts. SOme trucks also have other things built into the programming of the tranny with OD off such as engine braking to let the tranny help slow the truck down by slowing the downshifts.

Its a good idea to use OD off if you notice your tranny if shifting with a certain load.

[harvey lee]

Powerstroke nailed it.

I will tow something if I am on a flat road with no hills. Hilly roads I always use OD.

The tranny cost is simply to spendy versus the small loss in fuel mileage.

[S.D. Ice Angular]

Harvey,

I think you mean O/D "OFF" other wise you are completley backwards than most of us.

[PerchJerker]

On my Fords and Chevys, I almost always tow at highway speeds with the vehicle locked out of overdrive. This prevents shifting and the transmission runs cooler .... both very very good things for the life of your transmission.

The last Chevy I owned had a Tow / Haul feature on it. This only affected starting out from a dead stop, it did nothing at highway speeds. It raised the rpms for the shift points, so the truck was in the lower gears for longer (until higher rpms) before shifting into the next higher gear.

[BobT]

My 2009 F150 has the tow/haul mode feature. I also have a transmission temperature gauge. Pulling my boat I use the tow/haul mode and even on hilly roads from I-Falls to Drysden, ON, where it is shifting up and down a bit I noticed that my transmission temperature doesn't seem to climb any higher than it does running empty. I was expecting it to but so far it hasn't.

[harvey lee]

Harvey,

I think you mean O/D "OFF" other wise you are completley backwards than most of us.

I can be backwards at times but you are correct, I did mean off.

[Powerstroke]

BobT- if you are referring to the factory tranny temp gauge then they are nearly worthless. It does function so that if you hit the dangerous level, you will notice, but it does not make much movement to show the actual variations in the temp of the tranny.

Unless you add an aftermarket temp gauge you won't be able to see the changes in temps.

[upnorth]

The guy who rebuilt my truck tranny said if you are towing or hauling OD off.

[BobT]

BobT- if you are referring to the factory tranny temp gauge then they are nearly worthless. It does function so that if you hit the dangerous level, you will notice, but it does not make much movement to show the actual variations in the temp of the tranny.

Unless you add an aftermarket temp gauge you won't be able to see the changes in temps.

Maybe, and I understand you may have some knowledge and experience well beyond me but then I can't help but wonder how they could warrant their transmission if I do overheat it because the gauge fails. And also what does it say about the engine temperature gauge, charging system gauge, and other warning indicators? Are they junk too?

[96trigger]

$2000 taught me that OD needs to be off! Towed my 16 foot boat up north with my 98 silverado, bucking a 30-40 mph headwind, never noticed any shifting what so ever, but it completely fried my tranny. I will NEVER tow anything in OD again. I had no warning and I read the owners manual which said just what many of you guys are about shifting in and out of OD. It never did that. My 2011 silverado has the button for tow, but like what was mentioned before, it only changes the rpm shiftpoints, not the travel rpms. It also has a the +/- button on the shift lever. This basically allows you to shift it manually, I love this function for towing.

[Kyhl]

In my experience it is not that the tranny is shifting. My experience was the locking and unlocking the torque converter which heats things up quickly.

I cooked some tranny fluid towing into a wind by leaving OD on and letting the torque converter run unlocked for long periods of time. Heading from the twin cities to Vermilion on opener morning before sunrise. I may have been in a bit of a hurry since the trip was planned the night before.

I was on a tighter budget back then and lived with it. The tranny was ok. Changed the fluid but the torque converter shuttered pretty hard when locking up from that point on.

This was in the mid to late 90's. I drove that vehicle a few more years before replacing it in 2001.

[dan z]

Not sure if it was me hauling a boat in fifth or the higher miles on the clutch that fired mine a year ago, now I pull in fourth and still manage pretty decent mileage. Once again love the stick on the floor

[CaptainMusky]

In my experience it is not that the tranny is shifting. My experience was the locking and unlocking the torque converter which heats things up quickly.

vehicle a few more years before replacing it in 2001.

+25. The torque converter is what "takes out" an automatic tranny. Some people tow in od and watch their gauges including tach and don't realize the truck isn't in od at all because its only a couple hundred rpm. Newer vehicles have 5 or 6 spd trannies and eliminate the torque converter as lockup for the od. Much better.

having said that I have 230,000 miles on my 2000 sierra and tow in od all the time. I always watch rpm and know exactly where it should be at specific speeds. If I see rpm changes I will kick it out of od. No problems at all. I don't baby it. Pull a 19 ft boat but drain NOT flush tranny with new filter every 45000 miles.

[Kyhl]

having said that I have 230,000 miles on my 2000 sierra and tow in od all the time. I always watch rpm and know exactly where it should be at specific speeds. If I see rpm changes I will kick it out of od. No problems at all. I don't baby it.

I forgot about that. Yes, there is only a couple hundred RPM difference between OD on and converter unlocked versus OD off and converter locked. You can see it easily in the tack when slight moves to the peddle move the tack around. If the converter is locked the tack will not bounce around.

I do the same thing. If I can catch a long flat stretch or long downhill stretch where the converter will stay locked with OD on then I will leave it that way. As soon as the converter unlockes the OD goes off.

I make a game out of trying to anticipate the converter unlocking and beat it to the punch by dropping it out of OD so it can stay locked. I get disappointed when I miss it.

It's a way to pass the time on a 4am drive by yourself through the middle of nowhere.

[Jeremy airjer W]

Can some one explain to me why I would want to O/D on or off while I'm towing my boat? I've heard a mix of different things but not from really reliable sources. Just wondering what the benefits of having it on may be?

Thanks ahead of time!

Year, make, model, and engine size?

I rarely tow out of overdrive but my usual load is not that great. It all depends on the manufacturer and the conditions.

[Jeremy airjer W]

Maybe, and I understand you may have some knowledge and experience well beyond me but then I can't help but wonder how they could warrant their transmission if I do overheat it because the gauge fails. And also what does it say about the engine temperature gauge, charging system gauge, and other warning indicators? Are they junk too?

Even on the newer fords (I think this is still true), the oil "gauge" is nothing more than an oil switch. It is not a true indication of oil pressure. I realize it doesn't have anything to do with o/d but thought it was worth mentioning as it does imply to the integrity of the gauges.

[SkunkedAgain]

All of this torque converter talk is quite interesting to me, but I'm still confused. How do you tell if the converter is locked or unlocked? I just stepped up to a v8 F150 and was figuring that I could now tow in OD until I started getting to the I35 hills north of Hinckley. Unless I feel like I understand this torque converter nuance, I'll probably still keep the OD.

[Kyhl]

All of this torque converter talk is quite interesting to me, but I'm still confused. How do you tell if the converter is locked or unlocked? I just stepped up to a v8 F150 and was figuring that I could now tow in OD until I started getting to the I35 hills north of Hinckley. Unless I feel like I understand this torque converter nuance, I'll probably still keep the OD.

The only way to be certain is to know that under no load you run x rpm at 65mph. Say it's 2,200 rpms. then under a load you see that you are running 2,800 rpms in overdrive. Turning off OD might run it up to 3,000 rpms. At that point you know that the extra 600 rpms (2,800-2,200) are from the converter slipping when unlocked.

[BobT]

Even on the newer fords (I think this is still true), the oil "gauge" is nothing more than an oil switch. It is not a true indication of oil pressure. I realize it doesn't have anything to do with o/d but thought it was worth mentioning as it does imply to the integrity of the gauges.

Not trying to take this off topic but since you mechanics brought this up I'd like to ask. You say the pressure gauge doesn't show pressure but is either off (showing no pressure) or on (showing normal pressure)? What good is that?