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Over Drive Use

3K views 14 replies 7 participants last post by  Amelie 
#1 ·
So I know Over Drive is mainly used on the Interstate/Highway and when your above 50 MPH but is it okay to run with Over Drive off while driving on a non-interstate road when going above 50 MPH?

I like to go at brisk pace most of the time and I keep Over Drive off because your speed can fluctuate a lot when not in a highway situation where your speed is mostly constant.

:confused: By doing this does it harm the transmission or anything else? :confused:
 
#7 ·
It could actually help the transmission, less shifting back and forth has to be a good thing I would think. Also I believe a higher gear will also keep the trans temp down as there is less friction from shifting and running a higher gear (making an assumption based on the fact that they tell you to turn off OD for towing/heavy loads)
 
#11 ·
On the 42RE tranny, 1st and 2nd gear are underdrive gears ( the tranny input speed is higher then the output speed). 3rd gear is direct drive ( tranny input speed = tranny output speed) 4th gear is overdrive (the tranny input speed is lower then the output speed). With overdrive off, 4th gear is disabled.
Overdrive is there to reduce the fuel consumption and lower the engine noise.
In both 3rd and 4th gear the torque converter will be locked ( a clutch inside the torque converter will be engaged, making the input and output of the converter fixed, to reduce losses inside the converter and reduce significantly the heat buildup).
So it doesn´t matter that much if you use overdrive or not, it will at least not harm your tranny. You could normally expect a higher fuel use when driving at the same speed when in 3rd gear then in 4th, but as misfit77 wrote, for him its the other way around.
 
#12 ·
In both 3rd and 4th gear the torque converter will be locked ( a clutch inside the torque converter will be engaged, making the input and output of the converter fixed, to reduce losses inside the converter and reduce significantly the heat buildup).
The only time it will lock up in 3rd gear is when O/D is off. If driving in normally, it won't lock up until you get into 4th gear.
 
#14 ·
Yes, you are right. So if you would drive at a speed that it would stay in 3rd gear, it would be better to switch off overdrive to lower the tranny temp.
 
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