maybe stupid question but can someone explain me what the OD (overdrive I gues) function is for?

I have a Nissan Tiida and have a little switch on my auto-gear to swtich it off??

Dont have a clue what it would be for. When i push it feels like the car start making more rounds and seems to pull slower?

I guess it effects the oil supply maybe and how much a difference would it make when switched all the time?

HI

http://answers.yahoo.com/question/index?qi...04133305AAS63BO

http://www.thaivisa.com/forum/Nissan-Tiida-t188137.html

HD, Neither one of those links provided the answer I have always thought OD/off was primarily for. Towing. When towing the automatic transmission behaves as if it's always climbing a hill, and shifting into a lower gear, unless you select "OD off". That lower gear gives you more torque and power, which is called "overdrive." Same thing happens when you stomp on it to overtake. As the yahoo answers site correctly states, selecting "OD off" prevents the transmission from doing this, which is much better when you are towing so that it doesn't over use/overheat/damage the automatic transmission with all the shifting. The constant jerky shifts can cause problems for the truck by adding stress to the hitch and trailer. Also not good if you have trailer brakes. When towing, select "OD Off" and if you need a different gear, shift to down with the automatic shifter, that's what it's there for. (Good for compression braking when decelerating too) If you never tow, leave OD on at all times would be my suggestion, but maybe someone else here knows better? There may be some off-road application for it as well, not sure.

EDIT: Just realized, Tiida is the little car isn't it. I thought it was a truck. Maybe my towing idea is out then. I change my answer to "saves fuel in OD on mode" lol

Edited November 17, 200916 yr by Scubabuddha

Here you are, fill ya boots.

http://en.wikipedia.org/wiki/Overdrive_(mechanics)

O/D button is there for a simple purpose.

In overdrive it is like having and extra high gear.

Basically to make it simple for you. If you are driving round Bangkok or similar you want to be out of overdrive.

Say a trip to Korat on the highway put it in O/D and you will feel the difference in speed, same applies if you are going up a steep gradient behind a slow moving truck, take it out of Q/D.

Cheers

Basically to make it simple for you. If you are driving round Bangkok or similar you want to be out of overdrive.

Just leave it in D with the overdrive on. The transmission is controlled by a computer and will select the appropriate gear, modern slushboxes don't hunt like the old ones.

To answer your question, the Tilda has four forward gears, if you turn overdrive off it prevents the transmission from using the top, or fourth gear. Do you have an English version of the owners manaul? If you do no doubt it recommends driving in D at all times. In theory you can use the lower gears for engine braking, but brakes are cheaper then autoboxes and other drivetrain components.

Edited November 19, 200916 yr by proximity

Seems I'm the only one suggesting OD be turned off when hauling, so I had to do a little investigating. At wiki answers I found this response:

Overdrive

In simple terms, overdrive is the final/cruising gear. It reduces the power output by lowering the gear ratio. The overdrive mechanism increases fuel efficiency, and saves strain on the transmission and the drive train. When the vehicle is started the overdrive is always on, but it can be turned off by a switch button, which is often located on the shifter. Turning the overdrive off will prevent the vehicle from shifting into the overdrive when traveling at the speed of around 40 MPH. It is recommended that the overdrive is constantly on under normal driving conditions. It should be turned off when, for example, hauling heavy loads or going up a long gradual incline.

and at answers.com this one:

I will add that the car is allways in overdrive. if you take if off overdrive, a light will light up and if you step on the gas, you still go slow and will not change gear. Turn if off if going up a hill or heavy loaded.

Not saying anyone else's answers are wrong, it's just that my only experience in using "OD off" is only if I was towing something. I never knew all that other stuff.

Edited November 24, 200916 yr by Scubabuddha