always wondered this
Joined: Jul 2008
Posts: 6,575
Likes: 2
From: Las Vegas, Nevada
always wondered this
just because my grand prix doesnt have an OD off button or anything. so i have no experience with it.
but what does it do when i turn overdrive off? moreso, whats the point of doing it is what im trying to ask.
thanks lol
but what does it do when i turn overdrive off? moreso, whats the point of doing it is what im trying to ask.
thanks lol
it basically turns off 5th gear. I know in chevy fullsizes, it changes the shift points for better towing acceleration. May have something to do with torque converter lockup as well. It's a truck thing.
Joined: Jul 2008
Posts: 6,575
Likes: 2
From: Las Vegas, Nevada
yeah i guess my dads truck has it
cept its the "tow haul" button
firms up the shifts, and as you slow down it downshifts so that your gears help slow you down. pretty sweet.
i have noticed some firmer shifting in my truck when i use it, and it downshifts a bit quicker..
cept its the "tow haul" button
firms up the shifts, and as you slow down it downshifts so that your gears help slow you down. pretty sweet.
i have noticed some firmer shifting in my truck when i use it, and it downshifts a bit quicker..
Yes pretty much every car and truck have them. All the automatic vehicles I've driven or owned have had an OD button.
yeah it changes the shift points and gives you better gas mileage when on. I only turn it off like on the highway where its hilly, or I want to pass. With it off it stays in gear a lil longer I believe,
ok if it doesnt have a button, when you put it in gear, what do you put it on the "D" with a circle around it for overdrive, beside that is there just a plain "D"???, i know my gfs escort does NOT have a OD button, but you can euther put the gear in OD or D...
I know I used to use it when I was had my Cruise Control on when I would come to a big hill on the freeway. The tranny shifted smoother going back down to Drive if I did it before the hill rather then just letting it shifted on it's own once I was on the hill.
That is not OD, the D with the circle around it is drive, and the plain D is basically just 3rd gear. My dads old BII had that.
Member
Joined: May 2009
Posts: 64
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From: Monroe, OR
From what i have heard (correct me if i'm wrong), with overdrive the output shaft of the transmission which goes to the drive shaft is spinning faster than the torque converter which keeps your engine rpm down (over driving).
Hmmm I wounder I just went out and checked my sis's 2004 Buick Regal (very simmilar drive train to a regular Grand Pix) and the shift pattern goes P R N D 3 2 1. I know she only has a 4 speed auto for a tranny (3 gears and an overdrive) so i believe that if you were to shift into 3 to would be the same as turning the OD off.
1) automatic shifting is allowed in gears 1 through 4. By locking out 5th gear, it greatly reduces shift hunting at highway speeds.
2) when the O/D is canceled, the transmission's Coast Clutch is applied in 4th gear, making engine braking available. (The Coast Clutch is not applied in 4th or 5th in the default O/D ON mode.)
Without a trailer: O/D Cancel can often provide the same benefits when driving on roads through hilly/mountainous terrain with no trailer. Fuel economy will suffer at speeds above about 45 MPH on flatter roads, so it's a good idea to use O/D Cancel only when needed.
Hmmm I wounder I just went out and checked my sis's 2004 Buick Regal (very simmilar drive train to a regular Grand Pix) and the shift pattern goes P R N D 3 2 1. I know she only has a 4 speed auto for a tranny (3 gears and an overdrive) so i believe that if you were to shift into 3 to would be the same as turning the OD off.
EDIT: I sort of stand corrected. It appears some times that Overdrive can be a 1:1 to ratio as well:
Originally Posted by Wiki
How an overdrive unit works
The overdrive consists of an electrically or hydraulically operated epicyclic gear train bolted behind the transmission unit. It can either couple the input driveshaft directly to the output shaft (or propeller shaft) (1:1), or increase the output speed so that it turns faster than the input shaft (1:1 + n). Thus the output shaft may be "overdriven" relative to the input shaft. In newer transmissions, the overdrive speed(s) are typically as a result of combinations of planetary/epicyclic gearsets which are integrated in the transmission. In these cases, there is no separately identifiable "overdrive" unit. A number of such transmissions and transaxles are manufactured by Aisin, for use in vehicles produced by many different manufacturers. In older vehicles, it is sometimes actuated by a **** or button, often incorporated into the gearshift ****, and does not require operation of the clutch. Newer vehicles have electronic overdrive in which the computer automatically adjusts to the conditions of power need and load.
The overdrive consists of an electrically or hydraulically operated epicyclic gear train bolted behind the transmission unit. It can either couple the input driveshaft directly to the output shaft (or propeller shaft) (1:1), or increase the output speed so that it turns faster than the input shaft (1:1 + n). Thus the output shaft may be "overdriven" relative to the input shaft. In newer transmissions, the overdrive speed(s) are typically as a result of combinations of planetary/epicyclic gearsets which are integrated in the transmission. In these cases, there is no separately identifiable "overdrive" unit. A number of such transmissions and transaxles are manufactured by Aisin, for use in vehicles produced by many different manufacturers. In older vehicles, it is sometimes actuated by a **** or button, often incorporated into the gearshift ****, and does not require operation of the clutch. Newer vehicles have electronic overdrive in which the computer automatically adjusts to the conditions of power need and load.
i kno when i used it on a shop truck when i was younger, i was able to turn off the O/D and like posted, the engine would slow me down. i'd be able to slow down 10 kms/h just by hitting that little button.
That technically is OD since OD allows the tranny to go into top gear which is 4th in this case.
i knew that was D with an o around it was overdrive and and standalone D is drive.....doubting myself for a minute...the the original OB, does ur grandprix have the same setup as my gf's escort: a D with an o around it, and jsut a stan alone D that you can select with the gear select?
i know you were mostly wondering "how" overdrive works, but im just curious b/c you said you didnt have "an overdrive button or anything"
i know you were mostly wondering "how" overdrive works, but im just curious b/c you said you didnt have "an overdrive button or anything"
