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· ɹǝqɯǝɯ ɹɐln&#38
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Discussion Starter · #1 ·
Okay, so after googling around, i'm unable to find a definite answer.

Is it okay to switch between Drive and Overdrive or will that hurt your tranny :lol:

sorry for the noobness
 

· Mr. Negative Pants, ,
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14,898 Posts
http://en.wikipedia.org/wiki/Overdrive_(mechanics)

Automatic transmission - Wikipedia, the free encyclopedia

Wikipedia said:
OverDrive (D, OD, or a boxed [D])
This mode is used in some transmissions to allow early computer-controlled transmissions to engage the Automatic Overdrive. In these transmissions, Drive (D) locks the Automatic Overdrive off, but is identical otherwise. OD (Overdrive) in these cars is engaged under steady speeds or low acceleration at approximately 35-45 mph (56-72 km/h). Under hard acceleration or below 35-45 mph (56-72 km/h), the transmission will automatically downshift. Vehicles with this option should be driven in this mode unless circumstances require a lower gear. (emphasis added)
On most modern automatics, shifting into "D" from "OD" just tells the transmission computer to lock out the highest gear (which you'd only really want to do if climbing a steep grade or towing), so nothing mechanically happens when you shift the lever. If you engage "D" while in the highest gear, it'll just downshift. Even if the engine over-revs in the downshift, it'll likely hit a rev limiter and it'll be okay.
 

· Registered
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http://en.wikipedia.org/wiki/Overdrive_(mechanics)

Automatic transmission - Wikipedia, the free encyclopedia

On most modern automatics, shifting into "D" from "OD" just tells the transmission computer to lock out the highest gear (which you'd only really want to do if climbing a steep grade or towing), so nothing mechanically happens when you shift the lever. If you engage "D" while in the highest gear, it'll just downshift. Even if the engine over-revs in the downshift, it'll likely hit a rev limiter and it'll be okay.
:agreed:

There's almost no reason to switch out of OD for normal driving.
 

· NICE BLACKMACHINE YO
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7,256 Posts
Oh, I forgot: we have a car forum now. :lol: I was sure this was an amplifier question.
Me too. :lol:

I was about to make a facetious joke, and then realised I have next to zero experience with automatic transmissions, and I don't know an awful lot about them.

Off to educate myself on this forgotten technology!
 

· ɹǝqɯǝɯ ɹɐln&#38
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5,486 Posts
Discussion Starter · #9 ·
:agreed:

There's almost no reason to switch out of OD for normal driving.
I'm driving my older truck now since my current one has a blown tranny :ugh: :lol:

Anyway, it's a 94 Chevy S-10 that sat around for a few years at my folks house. I have it again now but it's really weak going up big hills interstate/highways so I have to downshift to D. Otherwise, once after I can go back to OD.

I'm just concerned that doing this won't mess the tranny up.
 

· NSLALP
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13,495 Posts
I'm driving my older truck now since my current one has a blown tranny :ugh: :lol:

Anyway, it's a 94 Chevy S-10 that sat around for a few years at my folks house. I have it again now but it's really weak going up big hills interstate/highways so I have to downshift to D. Otherwise, once after I can go back to OD.

I'm just concerned that doing this won't mess the tranny up.
You shouldn't have to do that. It should knock itself into 3rd gear from 4th (the overdrive gear) when appropriate. It may not shift exactly when you want it to, but a quick pump of the gas should knock it into 3rd to accommodate your desire to downshift. Unless something's wrong with it.
 

· Arrr, Matey!
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1,838 Posts
I remember my old '92 S10 blazer being sluggish going up hills too so I'd down shift into D as well. I believe it was a 4 speed, so shifting from OD to D would just lock it out of 4th. It won't hurt anything other than your fuel mileage, unless you are hammering on it. I also bet if you left it in OD and hammered the gas a little more going up the hill the computer would catch on and downshift for you.
 

· ɹǝqɯǝɯ ɹɐln&#38
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Discussion Starter · #14 ·
I have to basically almost floor it to automatically downshift which is why I manually do the downshifting. I never have to go down any further by hand.

I'm wondering if this truck is a 3 and +1 for the OD or if it changes the gear ratio.
 

· Registered
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what size engine do you have? because my '02 S-10 (4 cyl) wont go up a small hill without throwing a fit its super under powered and thats saying a lot considering that it cant weigh much more than 3000lbs :shrug:

plus the shift point in the automatic arent right because I had the stick version and I got worse gas mileage because I was making it shift like it should have been :2cents:
 

· ɹǝqɯǝɯ ɹɐln&#38
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5,486 Posts
Discussion Starter · #18 ·
Trans fluid is fine. The starter died last week and I checked everything two days ago when changing the starter out. It acted this way with the old trans and one that was put in a couple months ago (also replaced the O2 sensor and catalytic converter).
 
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