Does anyone here turn OD off?

[TerryMason]

So, I was towing my boat yesterday, and hit the overdrive off button for the first time. After some thought I realized that I've never had a reason to turn it off in the past (first time towing), and that I wasn't even sure if I should.

What do you guys think about turning OD off in general? I did some research, and it seems that OD doesn't even kick in until 43 mph. The idea seems to be that when towing, the transmission will hunt between OD and normal driving, and that this back and forth between overdrive will somehow harm the engine.

 

[Bounty__Hunter]

Too tall of a gear, like OD, or the constant hunting between OD and 3rd for the proper gear, will build heat in the transmission. Heat kills trannies, the hotter the transmission the shorter the transmission life.

I would leave OD off when towing, and consider installing an external transmission cooler.

 

[TerryMason]

I don't do alot (pretty much none) of towing. The jeep is just to small and light, plus the drums in the back don't help.

thanks bounty, that was pretty much what I had come to understand. I checked wikipedia, and it said to turn of OD when towing, and when driving in mountains.

 

[90Xjay]

down shifting can be the death of an Auto transmission

like Bounty said, the constant hunting between the gears causes them to heat up

I tow a 6000 pound TT and my GM vehicles had a tow haul mode which pretty much takes care of the down shifting by changing the shift points and pressures
but if I were towing and noticed frequent downshifts, I'd turn the OD off for sure

 

[David]

With many automatic transmissions without the "OD off" button, you can accomplish the same thing by simply setting your gearshift to the next lowest gear from "drive" (3rd in a 4 speed auto, etc.). I suppose that with a 6 speed auto (do trucks even have these?), the top two gears would be overdrives, so you'd have to go down to 4th to top out in a 1:1 gear ratio. Check your owner's manual for gear ratios.

 

[Utah_jeepster]

Terry, even normal off-roading can hurt automatic transmissions, deep mud and sand are the worst. And I am sure rock crawling is no better, but I recommend to everyone that they run down and buy an external cooler and ignore the instructions and hook it in series with your regular transmission cooler (down-stream/afterwords). Just running your transmission 10 degrees cooler will extend the life of the fluid 7000-10,000 miles and add years of reliable service.
I run one in both of my vehicles, my wifes truck and my jeep.

 

[KrazyJeeper]

I always tow with OD off, well since a year ago when my xj transmission overheated. That's one reason why I don't have the XJ anymore. LOL

 

[redrooster]

Rather than install a transmission cooler upfront, I would install a transmission temperature gauge if you don't already have one. I installed mine in the pan by drilling a hole and welding a bung that the sensor would thread into. There are kits that don't require the welding part (use a bulkhead type fitting with o-rings). You will have to drain the transmission to do this, but when all is said and done you will have the gauge and can take the sensor out to drain the pan without dropping it.
The reason for going with the temp gauge first is that you will know what temp your transmission is running so you can assess whether you need a cooler.

 

[TwistedCU]

OD off when towing, offroad, and when driving lots of hills or mountains.