Overdrive Switch?

[MilesandSmiles]

This feels like it might be an obvious question but I'm going to go ahead any way. We just brought home our "new to us" 2003 Southwind 37A. On the dash is a button to turn overdrive on or off. What does turning overdrive off or on do? Which position should I use for everyday driving, and when would I want to switch it?

[htowners]

In either heavy start and stop traffic, or very hilly areas I take mine out of Overdrive. My Allison 2100 has 2 overdrives so in rolling hills I just lock it out of 6th.
Steep downhill grades in 4th and the Trans brake, work well as long as you keep your speed in check.

[noleakman]

Leave it on all the time it will shift down when it needs to out of overdrive to 4th!

[MilesandSmiles]

Wow. What a great community. Thanks for the explanations!
Jeff

[wa8yxm]

The rule I follow is to drive with it on most of the time.. If the transmission is "Hunting" for the proper gear (Going in and out of overdrive) then I turn it off.. but so long as it goes into overdrive and stays there.. I let Allison control it (leave it on).

[gbopp]

Think of it as a 4 speed manual transmission. You can drive in 3rd gear while going down the highway. You have more power but, the engine runs faster and burns more fuel.

If you shift into 4th gear you don't have as much power but, the engines runs a little slower and burns less fuel.

Overdrive is just basically shifting to a higher gear.

[Dale_Traveling]

As time2roll stated if the transmission starts shifting in and out of OD a lot disable OD by using the switch.

[time2roll]

If the transmission is hunting turn OD off.
Same goes for the other gears... if transmission is hunting to choose a gear pull the lever and hold the lower gear.

[Passin_Thru]

Georgia Overdrive is when you kick it in neutral to go down a mountain.

[naturist]

Overdrive is for extra fuel economy, but makes climbing hills harder.

If the vehicle is unloaded, or lightly loaded, if the road is level or only slightly sloped, you want overdrive on to save fuel.

On the other hand, when fully loaded, or climbing a hill, or running into a stiff headwind, cutting off the overdrive will give you more power at the expense of higher fuel usage.

Overdrive is a higher gear ratio, and lets the engine run slower. When the load is heavy and power is needed, the lower gear ratio of overdrive-off allows the engine to rev higher and gives it more leverage/mechanical advantage.

Most vehicles with such a button can be (and should be) driven most of the time with overdrive on.