Automatic transmission questions
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Mountain Pass
Joined: Jan 2004
Posts: 213
Likes: 3
From: Phx/Az
Automatic transmission questions
To start this is the first vehicle I have owned with an auto. That being said, so far I'm getting used to my left foot not being needed to shift gears.
Most of my driving is in town 50mph max speed. Over the weekend I got out on the highway and at around 75mph I pushed the O.D. button cause that's what you do/what is for. Felt the tranny shift, the tranny got louder and engine RPM went up by 1K (was at 2.5K without O.D. went up to 3.5K with O.D.). Turned O.D. off for the rest of my trip.
1) Is this "normal"?
2) If this isn't "normal" what could be the cause of this?
3) What are your opinion/s on taking it to AAMCO for a service/inspection?
Thanks for your input.
Most of my driving is in town 50mph max speed. Over the weekend I got out on the highway and at around 75mph I pushed the O.D. button cause that's what you do/what is for. Felt the tranny shift, the tranny got louder and engine RPM went up by 1K (was at 2.5K without O.D. went up to 3.5K with O.D.). Turned O.D. off for the rest of my trip.
1) Is this "normal"?
2) If this isn't "normal" what could be the cause of this?
3) What are your opinion/s on taking it to AAMCO for a service/inspection?
Thanks for your input.
Frmr Ford Trans Engr
Joined: Aug 1999
Posts: 24,714
Likes: 2,640
From: SE Florida
Yes, that's normal. Don't take it to anyone, there is nothing wrong with the transmission. There is something wrong with your understanding.
If you look at the light that came on when you pressed the button, you would see that it says OD OFF. That means when the light is turned on overdrive is turned off. When on the highway the OD OFF light should not be illuminated. You have the function backward.
The RPMs you quote are labeled incorrectly. It is 2500 RPM with the overdrive on, and when you pushed the button you turned off overdrive and the RPM went up to 3500.
If you look at the light that came on when you pressed the button, you would see that it says OD OFF. That means when the light is turned on overdrive is turned off. When on the highway the OD OFF light should not be illuminated. You have the function backward.
The RPMs you quote are labeled incorrectly. It is 2500 RPM with the overdrive on, and when you pushed the button you turned off overdrive and the RPM went up to 3500.
Super Moderator
Joined: Apr 2004
Posts: 34,481
Likes: 2,801
As the owner of a '98 sohc and '99 ohv, I can tell you there is no need to fiddle with OD in any circumstance other than IF it's hunting on a long grade, or if you want to lock it out of OD for a long downhill to get more engine braking.
This is especially true if you have 3.73 gears and stock 235 75x15 or even the optional 255 70x16 tires.
This is especially true if you have 3.73 gears and stock 235 75x15 or even the optional 255 70x16 tires.
FTE Legend
Joined: Jun 2006
Posts: 31,930
Likes: 1,499
From: Ottawa, Ontario
This is interesting, it's the first time I have seen a documented example of a common misconception about vehicle operation that is perpetuated by pop culture. The common song lyrics of "punching it into overdrive" suggests dropping a gear to accelerate quickly is completely at odds with what the overdrive ratio in a transmission actually does.. which is to lower hwy cruise RPMs to achieve better fuel milage.
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