[Kenzo]

cause i wanna know

[Ole Yeller]

depends.... if your a manual and your talking about 5th gear, then just use it when your cruising at normal speeds.

if your an auto, then just leave over drive on.......

simple as that

[Nick_Rapitis]

is there any benefit to turning off overdrive in an auto?

[Roadhawg]

Originally Posted by Nick_Rapitis is there any benefit to turning off overdrive in an auto?

I lock mine out when running the 1/4 mile.
I try to avoid full power up shifts to 4th which applies 300-400 ft/lbs of torque to the OD band.

[TheUNZippee!]

Originally Posted by Nick_Rapitis is there any benefit to turning off overdrive in an auto?

Nope.

Typically they give you the option to turn it off if you are in a situation where the OD gear will be stressed. Such as if you are towing a heavy load, or going through mountains at a speed where it is constantly shifting in and out of OD.

[Nick_Rapitis]

k thanks

[nba1341]

Originally Posted by TheUNZippee! Originally Posted by Nick_Rapitis is there any benefit to turning off overdrive in an auto? Nope. Typically they give you the option to turn it off if you are in a situation where the OD gear will be stressed. Such as if you are towing a heavy load, or going through mountains at a speed where it is constantly shifting in and out of OD.

i thought it made it faster

[Nick_Rapitis]

i thought it would too....i know it sounds better with it off...

[TheUNZippee!]

Nah it doesn't make it faster. All you are doing is saving wear and tear on the od gear if it's necessary to turn it off. It's like a bicycle; imagine if you were this insanely powerful guy, and you put your 15 speed mountain bike in top gear, and then smashed on the pedals from a standstill. Chances are the chain is coming off, or something is breaking. The od gear is meant for cruising at higher speeds and improving fuel economy. If you go google gear ratios on any transmission, you will find that the od gear has a ratio of something like 0.70, wheras the first gear will have a ratio along the lines of 3.4 to 1.

[Nick_Rapitis]

i see...am i crazy when i say it sounds better with it off on my auto?

[97TunedMustang]

Kinda lol but really you probably think that because when your overdrive is off your car wont shift into 4th gear which will drop the rpms a bit. if your driving with OD off then it will stay in 3rd at a speed when it would normally be in fourth therefore giving you a different exhaust note cause the rpms are higher. Thats the only reason why it would sound different

[TheUNZippee!]

For racing? I've not seen any data that would indicate it makes your average street car faster in the 1/4. It may save some stress on the od gear, as roadhawg said.

But by disabling your od, all you are doing is simply preventing the transmission from going in to that gear. You are not changing the gear ratios in the tranny or how & when it shifts.

[Nick_Rapitis]

yeah the only sound difference was in higher gears....what about top end speed?

[TheUNZippee!]

Now THAT is something that will be affected, Nick.

Here are the gear ratios for your transmission:


Gear ratio - 1st 2.84 2.84
Gear ratio - 2nd 1.56 1.56
Gear ratio - 3rd 1.00 1.00
Gear ratio - 4th 0.70 0.70
Gear ratio - Rev. 2.32 2.32
Rear axle ratio 3.27:1 3.27:1

Note that as I said, the OD, or 4th gear, in your transmission is a .70 to 1.

This means that the output shaft is literally overdriven relative to the input shaft, allowing in turn the driveshaft, gears in the dif, the axles, and wheels to rotate faster, and thus giving the car a faster mph at a given rpm as compared to the 1.00 ratio in 3rd gear.

[Nick_Rapitis]

lol ok with all that said would top end be higher or lower with the O/D on? i obviously dont know a lot about this sort of thing like you and the other guys on here

[TheUNZippee!]

Higher with the od on.

Picture this in your head:

A shaft at the front of the transmission, spinning at a given rpm. That shaft is splined in to the back of the engine at the flywheel. Now picture a shaft at the rear of the transmission. This shaft is connected via a splined yoke to your driveshaft.

In between those two shafts, are different sized gears. The different sizes in turn give you different ratios, just as gears work on a bicycle.

Now when we say a gear has a 1:1 ratio, that means that both shafts are spinning at the same rpm. If you are talking about the overdrive ratio, which in this case is 0.70:1, that literally means that the output shaft is now spinning faster then the input shaft at the front of the transmission. Hence the term 'overdrive', the output shaft is being overdriven as compared to the input shaft.

Since that output shaft is connected to the driveshaft, and in turn, the differential gears, the axles, and the wheels, and if all those components are spinning faster than they would be as compared to the 1:1 ratio of 3rd gear, yes you get more top end when you are in overdrive.

[Nick_Rapitis]

nicely explained...i get it now....you really know your stuff man

[TheUNZippee!]

Anytime man

It helps when you are old like me and have been around. So I'm not smart, I'm just approaching middle age. lol