What does "Over-drive" do?

[ElFenix]

Originally posted by: gotsmack
you guys are horrible at answering questions. 4 posts aimed at me and I still have no answer.


yes or no : Is it safe (for the car) to push the over drive button while moving in an automatic or should I come to a stop first.

in other words, If I drive on the highway non-stop for an hour and toggel the overdrive on and off like 30 times. Will I damage the car?

no worse than any other shift an automatic tranmission would do. unless you're going like 120 and dropping down would rip the transmission out. i pop off overdrive when i need to get in a quick pass all the time, saves me from waiting to floor it before the transmission shifts and the engine gets up into the higher range.

 

[LS20]

Originally posted by: rh71
a lot of you are saying it's great for highway cruising... but what if you're just driving around town... wouldn't the 1:1 non-OD still use up more gas ? Wouldn't OD still serve you better on local roads... where even then you don't really need the power ?

OD implies a tall gear ratio, and the OD button merely prevents or allows the car to use that gear... that is, having the OD enabled does not necessarily mean the car is USING that tall gear.

so logisitically there is no reason to ever turn it off... aside from when youre going downhill and you want to force the car into a lower gear for engine braking, or when youre going uphill and your tranny stupidly hunts through gears suitable for the climb

 

[Crappopotamus]

Originally posted by: PCTweaker5

Originally posted by: Crappopotamus

Originally posted by: PCTweaker5

Originally posted by: Crappopotamus
overdrive is like an afterburner on a plane, which is similar to nos. its also got parts of a vtec setup. ive actually got an upgraded ecu od, ported and polished. my car is so fast with it on. yesterday i smoked a corvette, and he was all like 'oh snap i dont have overdrive thats sick yo'.

so basically, if you want to be fast and impress the chickas, keep your overdrive on.

hahaha what a joke! And afterburners are nothing like NOS, its refueled exhaust from the first burn which is then burnt again.

you dont know what the hell youre talking about. my dad is a race car driver on the nyrus circuit and my mom is a fighter jet pilot. i think i know what nos and afterburners are. n00b.

ps my moms fighter jet is the new model f27b with an upgraded direct port nitrous afterburner.

You sound like a little kid who lives in an orphanage! Good luck with life dude!

hahaha. i hope youre not as stupid as you sound...

 

[ElFenix]

Originally posted by: Crappopotamus

hahaha. i hope youre not as stupid as you sound...

:beer:

 

[Zenmervolt]

Originally posted by: Marauder911
Unless you are towing something very heavy, where you need more torque, leave it on. In an overdrive automatic transmission (most commonly a four speed), the first two gears are underdrive (engine turns faster than the rear wheels), 3rd gear is 1:1 (engine turns the same as rear wheels), and 4th gear is overdrive (the engine turns less than the rear wheels). When overdrive is turned off, your car only uses the first three gears. When overdrive is turned on, it will use all four. This means at a higher speed, the engine has the ability to turn lower RPM's, using less fuel.

Wrong. The engine always spins faster than the drivewheels. That's because of the differential gearing. In the first two gears (typically both "under-drive"), the engine spins faster than the transmission output shaft. In Third gear (typically 1:1, sometimes just very close to 1:1), the engine spins at approximately the same speed as the transmission output shaft. In overdrive, the engine spins a little slower (a typical overdrive transmission ratio is 0.8:1) than the transmission output shaft.

Because the final drive ratio (differntial ratio) is typically between 3:1 and 4:1, even in overdrive the engine is still spinning faster than the drive axles.

ZV

 

[ElFenix]

yup 'rear end' ratio is not considered for what is overdrive.

but there is so much bad info in here it would require a whole 'nother thread to correct it all.

 

[Zenmervolt]

Originally posted by: ElFenix
yup 'rear end' ratio is not considered for what is overdrive.

but there is so much bad info in here it would require a whole 'nother thread to correct it all.

I've stopped calling it a "rear end" because so many n00bs with FWD cars claim that their cars can't have a "rear end" because they are front-drive.

I'll bet that those solid drive axles without "rear ends" in all those FWD cars make it hard to go around corners.

ZV

 

I see a few correct answers but for once I am not going to make a comment or a statement of facts.

 

[Mallow]

change in the gear ratio I think... better gas mileage.

 

[yukichigai]

Overdrive just means your vehicle switches gears to maximize fuel economy. (Higher gear = less fuel used per mph) Turning off Overdrive is the equivalent of downshifting on a manual transmission. Barring a few instances you should typically drive with Overdrive on.

I turn Overdrive off when:

* I'm coming down a hill, so I don't have to break as much.

* I'm going through a long-ish stretch of uphill inclines

* I'm hauling a trailer and I want to be able to move without the transmission killing itself


Other situations can present themselves, but basically you do it when you either want more torque or want to slow down slightly.