over drive

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NickDsv6

Founding Member
Dec 1, 2001
683
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southern Indiana
Originally posted by bankz211
will my car go faster if i have my over drive off?

Your actual top speed will be lower because you'll be losing part of your gear range with it off. Your car might feel faster on hills and under a load, but that's just because it doesn't have to engage passing gear to get out of O/D. Turning off O/D is for hills and towing when the tranny wants to shift back and forth too much, any other time and you're just lowering your gas mileage.
 

NickDsv6

Founding Member
Dec 1, 2001
683
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southern Indiana
Originally posted by superstang101
what i was told when u are running overdrive, u are basically running with only 3 gears. so ur rpm's are running alot higher so ur gas milage will go down, but with more power, i could be wrong but thats what i was told

Either you typed it backwards, or you just understood it the wrong way. When overdrive is turned OFF then you are only using 3 gears; first, second, and third. Overdrive is like 4th gear, but it's called overdrive because it's just that, "Over drive." Your 3rd gear (drive) is a 1:1 ratio. Every turn of the input shaft to the tranny is a single turn of the output shaft going to your rearend. Overdrive is a 1:1.xx ratio, where the input is rotating at one speed and the output is rotating faster. It's harder for the car to gain speed with this ratio, hence it feels like you have no power. When you turn off overdrive, the engine uses 3rd gear and has a greater mechanical advantage. Basically, the ratio of 3rd makes it a little easier for the engine to pull, and you'll also be at a better place in the powerband, giving you more power on demand. Since your higher in the powerband (more rpms), the gas mileage is a little worse.
 

widowmaker

Founding Member
Jul 11, 2002
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i kinda experimented with it today and heres what i found......whenever your going over 50 and turn it off your car will run at hgiher rpms and when you have it on it will run at lower rpms because overdrive basically just makes your car work less hard at higher speeds :shrug: jus kinda wha ti noticed
 

NickDsv6

Founding Member
Dec 1, 2001
683
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southern Indiana
Originally posted by widowmaker
i kinda experimented with it today and heres what i found......whenever your going over 50 and turn it off your car will run at hgiher rpms and when you have it on it will run at lower rpms because overdrive basically just makes your car work less hard at higher speeds :shrug: jus kinda wha ti noticed

If you tried the same experiment at lower speeds, you could drive in 3rd and pull the shifter down to 2nd and you'd notice the same thing. It's just the nature of changing gears. O/D is just 4th gear, but it's called O/D for the reasons I stated above.
 

marvinmycat

Founding Member
Feb 13, 2002
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Buffalo, NY
O.K. Let's say you are racing someone from a dead stop. Do you turn the O/D off for better acceleration in a short sprint, or keep it on? Will it make a difference in a 1/8 traffic light to traffic light show-off race?

How about if you want to go an extra eighth to 1/4, will the O/D off make a difference there, or would you need the ratio for extra MPH?
 

SixPack

My Mommy has a Lightning
Founding Member
Over drive in a Auto is the same as 5th gear in a manual. unless the car shifts into it you ARE NOT USING IT. in the quarter miles unless your hitting over your top speed in 3rd the car will never see overdrive till after you stop accelerating. so having it off or on wont affterct tim in and sprint race
 
Unless your making a lot of power, you do not want to be in OD if you are trying to race someone. If the chance that your car did not down shift when you jumped on it, I would say that a bus might beat you. OD is for economy, not speed.

Now in my car, I make a lot of tq(450 rwtq), so OD in my car screams. I can hit 150 MPH in about 19-20(at the most) seconds going thru the gears and OD.

When my car was running 13's I absolutely hated it when it would not down shift during a race at higher speeds. Like if I was going 100 MPH and jumped on it and it did go into 3rd, but stayed in OD, pissed me off.

I don't think that my fiance's 99 V6 5 speed could beat my 89 GMC truck if she were in 5th and I was allowed to be in 2nd from a 60 MPH roll.