GenVibe - Community for Pontiac Vibe Enthusiasts

ok. I give up. What is this overdrive i have. I keep hitting the button to turn it off, and see my tach shoot up about 1-2k...it doesn't make sense to me, and the manual doesn't explain what purpose it serves. Please enlighten the ignorant one! Thanka!

Without, you have 4 speeds. With it, you have 5 speeds. I think it's mostly for fuel economie.

It also helps in towing. If you take overdrive off it's like putting your car from 4th to 3rd. For normal driving just leave it on and have fun.

Boy that owners manual has a terrible description of this feature (p 2-25). I think Shadow has the right idea - it takes your 4 speed and turns it into a 3 speed. Leaving it on is the way you help your fuel economy. It can be used in heavy traffic when you don't want to deal with the extra few tenths of a second before your car downshifts for passing. In other cars, it minimizes hunting between 3 and 4 gears when you're in hilly terrain. From what I remember of my auto Vibe test drives, none of these things was a major issue with the vibe. Towing is probably the only real use like shadow said. I don't have an auto so I can't try this - but it doesn't change the shift points does it? (Kind of like a sport mode)?

Please use the search feature when looking for a answer. If you don't find the answer or still have questions, then by all means post the question.You should find the answer to your question in this link.http://forums.genvibe.com/zerothread?id=305

quote:Without, you have 4 speeds. With it, you have 5 speeds. I think it's mostly for fuel economie.Awwww.... Sorry, wrong answer. Thanks for playing. Johnny, tell FoxTv about his parting gifts...Overdrive in the automatic trans (the only trans where there is a button to turn overdrive on or off) is nothing more than 4th gear (not 5th). When overdrive is off you are in 3rd gear. With overdrive on, you are using 4th gear.Overdrive is nothing more than any gear where the output RPMs are more than the input RPMs. In other words, a gear ratio less than 1.00Auto (2WD):1st : 4.012nd : 2.213rd : 1.434th : 0.98 (overdrive)Reverse : 3.27Final Drive Ratio: 2.96Auto (AWD)1st : 2.852nd : 1.553rd : 1.004th : 0.70 (overdrive)Reverse : 2.34Final Drive Ratio: 4.24In the 5-speed manual transmission, both 4th and 5th are overdrive gears:5-speed manual:1st : 3.172nd : 1.903rd : 1.314th : 0.89 (overdrive)5th : 0.73 (overdrive)Reverse : 3.25Final Drive Ratio: 3.94In the 6-speed manual transmission, both 5th and 6th are overdrive gears:6-speed manual:1st : 3.172nd : 2.053rd : 1.484th : 1.175th : 0.92 (overdrive)6th : 0.73 (overdrive)Reverse : 3.25Final Drive Ratio: 4.53

So my understanding is that O/D is in a sense a "virtual" 4th gear when on. That being said, can I use it to "downshift" as I would if there were an actual 4th gear on the shifter? For example, if I'm gonna pass someone, can I just click off the O/D and get the extra power I need for the pass, or should I still go down to 2 for that?P.S. -- I had searched prior to posting, but for some reason I didn't come up with anything. I think I split O/D into two words. Sorry for the double post.

quote:So my understanding is that O/D is in a sense a "virtual" 4th gear when on. No bro, your getting all turned around. Simply put, O/D IS your 4th gear. It is called Overdrive because it is made so your car uses less rpms to hold higher speeds (AKA the Interstate). Your car uses very little power when cruising in this gear, making you great fuel economy.The O/D button is so you can kick your car out of economy, low power mode, and into 3rd gear where you have decent passing power. This is also usefull around town where going into 4th gear is annoying and sapps your stop-and-go abilities. If you turn it off, you will only use 3 gears and that will guzzle gas on the highway. Hope this helped.

Flip-side is corect, overdrive is just 4th gear. If you turn overdrive off you are in 3rd gear. Turning overdrive off does not help or hurt performance to pass someone because pressing the throttle down causes the trans to downshift from 4th gear (overdrive) to 3rd gear. Sometime even to 2nd gear depending on your speed and how much you press the throttle. Using the button just does it manually.For 99% of the driving you never will need to turn the overdrive off. Just leave it on. If you are driving down a steep hill while towing, then you might want to turn the overdrive off to have engine breaking help slow you and save your brakes.

Ok, so I stand corrected. O/D IS my 4th gear. But what are the advantages or what is the point to making it a button rather than a shift position? Just curious! Thanks all.

That's a question I've never gotten a good answer for. I guess the designers would rather you shift with a button than moving the shifter and possibly shifting too far into 2 or neutral.

I've noticed that many American vehicles use a selector for OD, while many Japanesse makers use the button. Typically, there are reasons to force a car into 1st like when you are pulling a boat out of water or on unsure footing. Most cars allow 2nd gear start so you need that as an option. 3rd gear really isn't necessary so they rap it together with 4th.

Since my 89 Bonneville (3 cars ago) this is actually the first one I've had with O/D. My Sunfire and Grand Am both did not have it, they had a standard 4 speed. Wonder what makes them determine whether or not to make a 4 speed or 3 speed O/D...*shrug*