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Posted

so we've all heard that when you're towing you should keep the tranny out of overdrive.

 

the question i have is that if i am traveling on a very level highway cruising at 100 or 110km, let's say the 401, can i keep the car in overdrive as long as i monitor that the tranny is not downshifting all the time? this would mean better fuel economy, no?

 

I'm assuming this is why the car it's recommended to keep the car out of overdrive, so you don't overwork the tranny as it would continue to downshift/upshift on hilly roads, no?

 

any advice would be helpful.

thanks.

Posted (edited)

Sure, why not?

 

If it's changing gears all the time, you might want to drop it down a gear. My oldman and I have always towed in OD since I can remember, regardless of what truck we had at the time.

Edited by BillM
Posted

I do the same , helps if you have a tachometer.

 

What type of vehicle and what is the estimated load you will be towing ?

 

Tranny cooler is always a good investment as well.

 

TB

Posted

I owned a 1985 Chev P/U and took the tranny out after 5 years of towing in O/D. Same thing with a 1991 Suburban, twice. Then i read the owners manual and learned not to tow in O/D. My service manual for my G. Cherokee also recomende no O/D when towing as did my 2006 Liberty, needless to say, i will heed that warning. I think a lot has to do with the weight of the load and i think most people underestimate the amount of weight they are pulling after we load up our boats with extra batteries, gear, etc.

Posted
I owned a 1985 Chev P/U and took the tranny out after 5 years of towing in O/D. Same thing with a 1991 Suburban, twice. Then i read the owners manual and learned not to tow in O/D. My service manual for my G. Cherokee also recomende no O/D when towing as did my 2006 Liberty, needless to say, i will heed that warning. I think a lot has to do with the weight of the load and i think most people underestimate the amount of weight they are pulling after we load up our boats with extra batteries, gear, etc.

I don't discount what Kaiser is saying above (welcome by the way), but I always slip it into OD when I get up to hiway speed and know it will stay there for a few hours. Other than that it stays in drive.

Jim

Posted

I've never towed a boat, but I would tend to think the OD is designed to cruise the vehicle's original weight & a reasonable load IN the vehicle, and does not factor in the extra load it has to bear while towing another object. Even if you're driving on a level road, you need to consider the drag caused by the load being towed & even if the difference is not huge, it will ultimately have its effect on the transmission if subjected to it repeatedly.

Posted (edited)

My forte is not transmissions but here is what I know. In most automatic transmissions when you are in drive (3rd gear) your transmission is turning the same rpm as your engine at the input shaft as it is at the output shaft. Therefore it is not turning any internal gears creating heat. Heat is a killer when you are pulling extra weight. The overdrive gear will allow the output shaft to turn at a higher rpm than the input and it is going through another gear adding heat. Also the overdrive gear in many automatics isn't designed to pull extra weight and will wear and heat up.

My advise-don't use OD when pulling a load.

Edited by Bernie
Posted

I have a Dodge Dakata and the owners manually says to not use overdrive while towing. I'm assuming this is all the time, even on open road at normal speed. I don't think it makes any specific reference to whether you're changing speeds a lot vs. open road at a constant speed. I don't use overdrive when towing the boat - at any time.

Guest skeeter99
Posted

here it is plain and simple

 

if you are towing and your vehicle is searching constantly for gears upshifting and downshifting constantly then turn your OD off!!!!

 

but

 

if your trans is not searching for gears putting on OD will not hurt or make a difference (except fuel mileage will be better with OD)

 

if you are towing on flat road OD is better

 

if hilly etc turn it off

 

that is what the swith on the dash is for LOL!!!

 

I tow my bass boat with my durango at 110kmh with od on

Guest skeeter99
Posted
My forte is not transmissions but here is what I know. In most automatic transmissions when you are in drive (3rd gear) your transmission is turning the same rpm as your engine at the input shaft as it is at the output shaft. Therefore it is not turning any internal gears creating heat. Heat is a killer when you are pulling extra weight. The overdrive gear will allow the output shaft to turn at a higher rpm than the input and it is going through another gear adding heat. Also the overdrive gear in many automatics isn't designed to pull extra weight and will wear and heat up.

My advise-don't use OD when pulling a load.

 

 

no shifting up and down of gears increases heat that will kill the tranny

 

while I am towing in OD the tranny temp only goes up 1 degree in OD the temperature actually increases more in the tranny when I aint towing anything

Posted

All replies that mention heat are 100% on the money.

 

Your transmission will heat up rapidly when in OD and you'll end up cooking the bearings in your Torque converter. Generally speaking, it's about $800 to replace the TC on most vehicles. You won't know anything is wrong until it's too late.

 

Suck it up, pay the extra $ in gas while towing.. :)

Posted

The problem with towing in OD with an automatic is that the engine RPM is to low, thus the pump speed is too low and not enough transmission fluid is circulated around the transmission to keep it cool under a towing load. A transmission cooler should help, but I would still follow the manufactures recommendations.

 

It has been a few years, so the details are fuzzy, but I do know that older GM trucks (80s and early 90s with 700R4 and 4L60) had I think a 7 vane transmission pump which was poor at the best of times. The newer transmissions have a 13 vane pump (4L60E?) which improves performance at lower RPM.

 

To get around all of these problems, buy a truck with a stick shift.

Posted

I pull my Lund Baron (not light!) all the time in OD with my little 4.6 (less than 300cuin) Triton that's in my F150.

 

As others said tach (or ear) is important. Before grades be sure to tap the pedal and get it kicked down a gear.. BEFORE the grade!

 

Makes a 1/4 tank difference in a 4 hour trip vs leaving it in Drive... truck has 100K on it now with no indications of hurt.

Posted

Some years ago I towed with my wife's Bronco II. Using overdrive only down hill and on the flat. If I remember correctly the tranny rebuild was just over $800. I haven't pulled anything in OD since.

Posted
I am with Wayne on this one.

 

 

Me too. I tow under normal curcumstances in OD. If I'm in a hilly area, or slowing/stopping frequently, I drop it into Drive. If you know when your tranny should be shifting, you can make it shift itself. A lot of people just get in and hit the gas, but have no clue when or why the tranny is shifting.

 

Sinker

Posted
Me too. I tow under normal curcumstances in OD. If I'm in a hilly area, or slowing/stopping frequently, I drop it into Drive. If you know when your tranny should be shifting, you can make it shift itself. A lot of people just get in and hit the gas, but have no clue when or why the tranny is shifting.

 

Sinker

 

 

That's why it should be mandatory that everyone know how to drive a standard. Even people who only drive auto should have a clue what is happening in there

Posted

follow your owner's manual recommendations, in most cases it will tell you not too. Overdrive components are meant to support the requirements of the vehicle alone and not that of an additional trailer. I use my judgment here though, say if all I have is my aluminum boat around a 1000lbs on the flat with the wind behind me I will use OD.

Posted

I have a 96 Chev with 278000km on the original trans. It has towed ALOT, often in excess or 10000lbs. Always in OD.

...but it is a turbo diesel.

 

Transmission heat is a result of friction. Frequent hunting in and out of OD, or converter lock and unlock results in a lot of friction. If you're pulling fairly light with a truck and on level ground at highway speeds, I would think you should be ok in OD. As soon as you slow down, or come to hills and it starts hunting, pull it into drive.

I think most of the time when your manual tells you to pull in drive, the manufacturer is worried about warranty issues caused by the guy who wants to pull a 5th wheel at 80kmh through the mountains. Sure death for a trans in OD.

Posted (edited)

strictly tow in D no OD. been told by many a mechanic to do so. i would rather spend the extra few bucks in fuel than a rebuild. my jeeps only a 4.0L and i pull a boat/trailer combo that's probably in excess of 2500lbs loaded.

 

do miss a 5spd and wish my jeep was a standard though. not easy to find when buying used, slushboxes are usually all that's available.

Edited by Raf

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