Im sorry if this is retarted but can some1 really explain to me what Overdrive really is?? how does it work????
I want to learn more and this is something I really dont know..

Please some1 give me some insight.

 

Automotively speaking the gear ratio for drive, or the D on your gear shifter has been 1:1. For every revolution the engine makes so does the output shaft on the transmission. The rearend ratio also plays an important part in this. Say for example you have 3.73's in the rear end of your car and have a 3speed automatic. In first gear the trans is 2.52, second gear is 1.52 and 3rd is 1.0 respectively.

In 3rd gear at 70mph you would be turning about 3400rpm with a 26inch tall tire.

An OVERdrive transmission is a 4speed automatic. Drive is the same ratio 1.0 the over drive gear is .70 depending on what transmission it is. what this does is it lets the car go down the road at the same speed but the engine is not spinning as fast which is easier on the engine and not as noisy if you have loud exhaust and better on gas mileage.

In 4th gear at 70mph you would turning 2600 RPM's with a 26in tall tire.

Most manual transmission have overdrive and the T56 which they put in Vipers/Vettes/Camaro and Firebirds have a double overdrive so you can run a deeper gear in the rear end and still have good fuel economy.

Hope this helps.
Jason

 

thanks alot man that helped out alot so basicly the Overdrive is the tranny making it easier for the engine at high output, One question I have a friend that is sure that overdrive is a form of downshifting I don't believe him but then I dont really know. is it possible??

 

I have never heard of overdrive as a type of shifting. I have heard of truck drivers shifting into neutrul when going down big hills and calling it George E Overdrive, where that term came from I don't know.

 

If I press my foot down I feel a change that is overdrive right?? since the feel of it feels like that car downshifting I guess it is reasonable to assume its downshifitng, but its if like you are in second and you slam the gas the car can't shift to first and actually pick up speed am I correct I mean its to heavy of a shift to increase over second.
Im sorry keep bothering you LilJayV10 with my questions but it would help me a whole lot, im just learning this stuff.

 

Yes if you push down on the pedel far enough it will down shift into the next gear given you are below a certian speed or mph. What I mean is if you are going 45 mph in drive and push the pedal way down it will downshift into second gear but not first because the engine RPMs would be way to high. And depending on where the engine is in it's powerband on the downshift will depend on how fast the car moves.

You are not bothering me, its good you are wanting to learn. I ask questions all the time, nothing wrong with that.

Jason

 

So If I slam the gas the car will kick into overdrive and that is basicly it going down a shift??

 

Switch that. If you are in over drive and slam the gas your car will down shift into 3rd gear making the engine rev higher and therefore make more power. And Overdrive is for high speed not high output. Drag cars have no overdrive it actually can hurt the acceleration of your car. Top speed is higher with lower overdrive gears but acceleration is better with lower gears.

 

I notice all too often on my 700R4 that in OD my car will switch to it about 45 MPH while I'm still gaining speed. And they say manually shifting on an automatic isn't recommended. So does that mean I shouldn't shift from D to OD when I get my desired speed? What would you suggest?

 

I dont recomend shifting an auto trans either unless you have had your trans rebuilt for such purpose.

The 700 will downshift into 3rd if you are at 2/3's or greater throttle. When you are driving at 60 and up, like highway, your car will be in overdrive. You will notice that if you drive at 70-80mph your rpms might be around 2k-2.5k, but if you put it into D, your rpms will soar. OD is another GM invention to help massive gas consumption by not having your engine work that hard to move the car. You can be coasting at a certain mph and still be in OD, but if you nail it the trans will downshift.