O/D on or off?
Junior User
Joined: Mar 2004
Posts: 55
Likes: 0
Overdrive is the only gear ratio where the output shaft of the transmission is spinning faster then the flexplate on the engine. Good for fuel economy at high speeds. The disadvantage is lower tourqe at the wheels. Like the guys said the only good reason to take it off is to run with a trailer. Or if you are in slick conditions some may think you can use it to "engine brake". Although it doesn't work as good on an auto.
-ii
-ii
Senior User
Joined: Apr 2004
Posts: 105
Likes: 0
From: Charlotte NC USA
On the way to work each morning I travel a 55 mph 2-lane road. With the cruise set at 60, one section travels downhill.
In OD the truck wants to freewheel up towards 65. A radar cop sometimes sits at the bottom. Turning off the OD lets the truck engine brake, maintaining speed at 60/61 mph.
Cool.
In OD the truck wants to freewheel up towards 65. A radar cop sometimes sits at the bottom. Turning off the OD lets the truck engine brake, maintaining speed at 60/61 mph.
Cool.
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Senior User
Joined: Mar 2004
Posts: 345
Likes: 0
From: Saline, MI
I don't even take it out of O/D when towing unless it's something really heavy that makes it keeping shifting in and out of O/D.
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Elder User
Joined: Mar 2004
Posts: 559
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From: CT
Towing in OD is OK as long as the truck is not shifting constantly. When I tow I use OD for flat or downhills, but turn it off for uphills, especially if the hills are small and short because that is when the tranny will shift back and forth.
Senior User
Joined: Apr 2004
Posts: 170
Likes: 0
I just returned from a trip to Moab UT, 2200 mile round trip, pulling a 7000# trailer. You can pretty much tell when you need to turn the O/D off. The truck will start to hunt for a gear. I usually had to shift out of O/D when driving into a head wind or a long slight grade. On steep grades I was on the gas so much the truck naturally shifts to third, and good luck pulling a 7k trailer up a steep grade at highway speeds(55 max, I dont like to exceed 3200 rpm for any continual time). Down hill you want the engine breaking so I truned the O/D off. There is a considerable difference in gas mileage. I tried the O/D off on a 200 mile trip and got 8.5 MPG. This last trip switching in and out of O/D I average around 11 MPG. I figure Ford has engineered in the idiot factor and has programed the computer to adjust under heavy loads.
Just as a side note, Every time I filled up, I grabed the tranny cooler and check fluids, it was always warm but never hot to the touch, and the fluid still smells good(not burned). Once I got used to the way the tranny worked I settled the truck into a nice 70 MPH average.
Just as a side note, Every time I filled up, I grabed the tranny cooler and check fluids, it was always warm but never hot to the touch, and the fluid still smells good(not burned). Once I got used to the way the tranny worked I settled the truck into a nice 70 MPH average.
Senior User
Joined: Jul 2003
Posts: 332
Likes: 0
There's a certain hill I go up several times a week. It's curvy and you can only go about 35 MPH. I turn off OD in this situation. I've noticed a couple times when it's kicked in at a low speed, the engine stumbled and pinged for a brief second before it realized...hey!...I need to downshift! 
So I turn it on to avoid that. The truck may be smart, but it's not perfect. I try to make up for it where it slips up 
When I go on my annual Gatlinburg, TN trip next month, I'll surely turn it off while going up the mountain. That's only a 45 MPH drive so it's worth it to turn it off there. Otherwise, it's always on and I see no reason to turn it off except for towing and slow hill climbing.
So I turn it on to avoid that. The truck may be smart, but it's not perfect. I try to make up for it where it slips up When I go on my annual Gatlinburg, TN trip next month, I'll surely turn it off while going up the mountain. That's only a 45 MPH drive so it's worth it to turn it off there. Otherwise, it's always on and I see no reason to turn it off except for towing and slow hill climbing.