Motoring For Dummies - All Your Car & Driving Questions Answered H

[yhance]

Much better if you have a repair manual for both mechanical and electrical...this helps in spotting mechanical and electrical troubles and the part nos...

[masi]

I've been meaning to ask motorists for a long time this question regarding the use of the "overdrive" in automatic transmissions. To my understanding, the O/D is the equivalent of the 5th gear in manual transmissions. When you start your car, assuming it has automatic transmission, the O/D is usually switch "on" as a default. In city driving like ours is there any advantage to having the O/D switched "on" or "off"?

 

Please give me your insights.

 

 

BTW, as I mentioned, when I start my car's engine, O/D is always "on" so I drive around the Metro with it. In rare occasions I switch it "off" and I get more torque and engine revs higher before it shifts to a higher gear.

[troubleshooter8]

When using overdrive, the car's engine RPM drops, reducing engine wear and normally saving fuel. You should refer to the owner's manual for the proper speed to run at overdrive. However, all engines have a range of peak efficiency; it is possible for the use of overdrive to keep the engine out of this range, thus cutting into any fuel savings from the lower engine speed.

[bogliboi_blue]

Overdrive (O/D) is a fancy term for the automatic transmission's top gear. In a typical four-speed automatic gearbox, O/D simply refers to 4th gear.

 

When you drive with overdrive turned off on a four-speed auto 'box, you are effectively driving with just the three remaining gears. Even if the vehicle reaches a high enough speed to use 4th gear properly, the gearbox will not upshift and will remain in 3rd. This is handy for overtaking and moderate engine braking (e.g. when driving downhill on a steep grade), but it makes the car use more fuel and run noisier on a steady-speed cruise.

 

The most prudent thing to do is to leave O/D on. Unless you really need to override the auto 'box's programming, let the 'box do the shifting for you. Most automatics are programmed for economy driving by default.

[howard_the_duck]

is it a good idea to run overdrive on NLEX then run at normal when you reach EDSA?

[bogliboi_blue]

No.

 

The reason why overdrive exists is to save fuel and increase the refinement. Driving on a highway at a high-speed cruise with it OFF is going to be much, much harder on your wallet.

 

Besides, overdrive is NORMALLY TURNED ON by default. Leave it on.

 

Edit: I think a lot of people are getting the wrong idea from the name "overdrive" as if it's going to give you some sort of nitrous-like boost. It's nothing more than top gear. If you were driving a manual-transmission car you'd be foolish or extremely ignorant to stay at first gear all the time, right? It's the same with automatics.

Edited October 28, 2007 by bogliboi_blue

[mr_pussywarmer]

i used to drive manual but now my car is matic.....i always shift the gear (from D to 4th or even low to 2nd) anytime im driving on "UPHILL", going to high speed ramp while overtaking or high traction is required.....but most of the time, city driving i keep it in "D"...

 

 

i read it from the manual.....it is safe for the car engine to shift from "D" to lower gear especially while driving uphill....

 

please correct me if im wrong...im not an expert in this....

[bogliboi_blue]

^ Tama yan.

 

When you shift from "D" to "2" you're locking out all gears except first and second. This will give you engine braking and/or increased acceleration. Shifting to low gears like this is recommended for steep downhill driving (e.g. Kennon Road or the Shangri-La Plaza covered parking ramps) to prevent burning your brakes out.

 

Turning overdrive off does the same thing, except that it locks out only your top gear.

 

On Honda auto 'boxes you turn off overdrive by shifting from "D" to "D3"---effectively locking out all gears except first, second and third. It's the same thing.

[id6230]

As far as my limited knowledge in transmission mechanics can say with certainty, OVERDRIVE switch should be ON at all times except in driving conditions that dictates the use of lower gear only (1 & 2).

[masi]

Overdrive (O/D) is a fancy term for the automatic transmission's top gear. In a typical four-speed automatic gearbox, O/D simply refers to 4th gear.

 

When you drive with overdrive turned off on a four-speed auto 'box, you are effectively driving with just the three remaining gears. Even if the vehicle reaches a high enough speed to use 4th gear properly, the gearbox will not upshift and will remain in 3rd. This is handy for overtaking and moderate engine braking (e.g. when driving downhill on a steep grade), but it makes the car use more fuel and run noisier on a steady-speed cruise.

 

The most prudent thing to do is to leave O/D on. Unless you really need to override the auto 'box's programming, let the 'box do the shifting for you. Most automatics are programmed for economy driving by default.

 

 

is it a good idea to run overdrive on NLEX then run at normal when you reach EDSA?

 

 

No.

 

The reason why overdrive exists is to save fuel and increase the refinement. Driving on a highway at a high-speed cruise with it OFF is going to be much, much harder on your wallet.

 

Besides, overdrive is NORMALLY TURNED ON by default. Leave it on.

 

Edit: I think a lot of people are getting the wrong idea from the name "overdrive" as if it's going to give you some sort of nitrous-like boost. It's nothing more than top gear. If you were driving a manual-transmission car you'd be foolish or extremely ignorant to stay at first gear all the time, right? It's the same with automatics.

 

 

i used to drive manual but now my car is matic.....i always shift the gear (from D to 4th or even low to 2nd) anytime im driving on "UPHILL", going to high speed ramp while overtaking or high traction is required.....but most of the time, city driving i keep it in "D"...

i read it from the manual.....it is safe for the car engine to shift from "D" to lower gear especially while driving uphill....

 

please correct me if im wrong...im not an expert in this....

 

 

^ Tama yan.

 

When you shift from "D" to "2" you're locking out all gears except first and second. This will give you engine braking and/or increased acceleration. Shifting to low gears like this is recommended for steep downhill driving (e.g. Kennon Road or the Shangri-La Plaza covered parking ramps) to prevent burning your brakes out.

 

Turning overdrive off does the same thing, except that it locks out only your top gear.

 

On Honda auto 'boxes you turn off overdrive by shifting from "D" to "D3"---effectively locking out all gears except first, second and third. It's the same thing.

 

 

As far as my limited knowledge in transmission mechanics can say with certainty, OVERDRIVE switch should be ON at all times except in driving conditions that dictates the use of lower gear only (1 & 2).

 

 

thanks for your response... great inputs!!!

[caloyski65]

mga minor repairs, check-ups at maintenace ay nagagawa ko except yun mga major trouble......it helps a lot if you knew something bout repairs sa mga sasakyan in case na masiraan ka while driving...at di ka basta maloloko ng mga mekaniko sa mga motor shops..... :thumbsupsmiley:

[stockboy]

DIY guy here...as long di masyado complicated gagawin...i always do it by myself. stress reliever din ito

[bogliboi_blue]

I'm not much of a repairer myself. I keep myself to fluid maintenance and tire pressure checking.

 

I do opt to closely watch the mechanics do their thing when they make major repairs on my car. There's a lot you can learn from them (and you see how critical certain parts are on your car, like the CV joints and clutch assembly).

[johnlove]

Sometimes if I don't have any choice, I have to do it myself.

[id6230]

I can replaced the headlight bulb and I can change the oil and filters. Beyong that, I don't dare especially because newer cars are computerized already.