Should I Be Using Overdrive When Towing?

[Soundguy]

I agree with the others.. if you have a tow/haul mode.. use it and let the computer tdo the hard work.. otherwise.. don't use OD.. the constant lock/unlock o fthe TC will cause wear.

soundguy

 

[aczlan]

The purpose of overdrive is to lock the torque converter so that there is no slippage between the engines crank and the transmission input shaft.

Matt_Jr, I hate to disagree with you but what you are describing is generally called a Locking or Lock-up Torque Converter, it sits between the engine and the tranny where the clutch would go on a vehicle with a manual tranny (more info here (Wikipedia)).
The overdrive on the other hand is the last unit in the transmission or is bolted onto the rear of the transmission (on older vehicles), it makes the driveshaft spin a little faster than the final gear on the transmission, this gives you more speed but less torque, this imporves your gas mileage as the engine spins at lower RPMs, however the lower torque available causes the tranny to downshift more often, kick in and out of overdrive more, or both when under heavy loads, this is hard on the transmission and can cause premature failure. for more info on how a overdrive works there is a decent description here (Wikipedia)

with the cars I have had, there seems to be about 1/2 of a gear worth of speed increase and slightly better mileage.

Aaron Z

 

[bake321]

Why is everyone an expert? My manual says it is fine to use OD when towing. It also says to come out of it if your having a lot of down shifting. When mine shifts down I turn off the OD until I am at the top of the hill and then return to OD. Things do change over the years, read your manual to be sure.

Bake

 

[Matt_Jr]

Matt_Jr, I hate to disagree with you but what you are describing is generally called a Locking or Lock-up Torque Converter, it sits between the engine and the tranny where the clutch would go on a vehicle with a manual tranny (more info here (Wikipedia)).
The overdrive on the other hand is the last unit in the transmission or is bolted onto the rear of the transmission (on older vehicles), it makes the driveshaft spin a little faster than the final gear on the transmission, this gives you more speed but less torque, this imporves your gas mileage as the engine spins at lower RPMs, however the lower torque available causes the tranny to downshift more often, kick in and out of overdrive more, or both when under heavy loads, this is hard on the transmission and can cause premature failure. for more info on how a overdrive works there is a decent description here (Wikipedia)

with the cars I have had, there seems to be about 1/2 of a gear worth of speed increase and slightly better mileage.

Aaron Z

No hard feelings but don't believe everything you read. What you are refering to is an overdrive unit that bolts onto the rear of the transmission. In modern automobiles including light trucks when the vehicle is in it's highest gear the vehicle is in overdrive when the torque converter is locked. This is usually done by applying hydraulic pressure to a shaft that pushes into the torque converter to effectively "lock the converter" and approx 3% slippage is allowed for diagnostic purposes. Although the torque converter is called a lock up converter it is still referred to as overdrive when it is locked. On most vihicles if overdrive is turned off the computer will unlock the converter and shift into a lower gear depending on engine load sensed by the throttle position sensor, manifold absolute pressure, or mass air flow sensor. If you wanted to buy an overdrive unit for your vehicle that will work in conjuntion with you overdrive transmission look up Gear Vendor.

 

[Builder]

No hard feelings but don't believe everything you read. What you are refering to is an overdrive unit that bolts onto the rear of the transmission. In modern automobiles including light trucks when the vehicle is in it's highest gear the vehicle is in overdrive when the torque converter is locked. This is usually done by applying hydraulic pressure to a shaft that pushes into the torque converter to effectively "lock the converter" and approx 3% slippage is allowed for diagnostic purposes. Although the torque converter is called a lock up converter it is still referred to as overdrive when it is locked. If you wanted to buy an overdrive unit for your vehicle that will work in conjuntion with you overdrive transmission look up Gear Vendor.

In my light truck, all gears (except first gear) are available for lock up.

 

[john_bud]

If the manual says OD, then use OD. It should have a tow/haul or similar, be sure to use that.

If you don't use OD, you will lose about 20-25% mpg's - that's a bite in the wallet! Modern trucks are designed to towin OD with the Tow/haul buttons pressed - controllers are much smarter than they were in the 80's when OD's first got popular!!
jb

 

[Matt_Jr]

Why is everyone an expert? My manual says it is fine to use OD when towing. It also says to come out of it if your having a lot of down shifting. When mine shifts down I turn off the OD until I am at the top of the hill and then return to OD. Things do change over the years, read your manual to be sure.

Bake

Althogh I don't consider myself an expert as a master automotive technician I do know a little how they work having fixed quite a few. As far as when you (Bake) turn off your overdrive you are doing things exactly how they should be done for best fuel economy and saving your vehicle wear.

 

[bake321]

No Matt, you are an expert, and you agree with me!! That's good.

Bake

My smilies won't work

 

[Matt_Jr]

No Matt, you are an expert, and you agree with me!! That's good.

Bake

My smilies won't work

Something I forgot to add-Although the computers are very good at controlling overdrive shifts in the transmission, they don't foresee that hill you're about to drive up or the 10 you know are around the corner. If you feel comfortable operating your overdrive over the computer you can control things a little better while driving. It won't hurt anything pushing that OD button while moving. Of course you always should consult your owner's manual; however understanding how they work can allow you to operate your truck better than the computer can foresee. One day that may change when we can let the truck drive itself. I'll have to turn that feature off though, I like to be in control.

 

[bake321]

I have been making numerous trips between Arizona and Kentucky, leaving again on Saturday, 1750 miles one way. I've pulled everything from horses to a 5th wheel RV. The only way out of the valley of the sun other than I-10 is up a mountain. I'm getting good at pushing the button.

Bake