O/d On Auto Tranny

[noaim]

If this has been cleared in another topic, please link...

Whats the O/D function used for in Auto Trannies?

Whats the Advantage of having it on rather than off?

[neXGen]

well from what my buddy has told me dude.. the O/D (overdrive) is basically to be off when crusing in the city below 60 kmph.. it gives you added control and braking ability though at times you cannot feel that difference.. once you hit above 60 it is better to switch it on as the O/D being off has a pull back effect which will be felt when you are above 60kmp and wanna brake..

in the sense, if you want to brake in a hurry from high speeds such as 100 odd, switching off the O/D would really assist.. within the city though, where 60kmph is a max, it is better to keep it off. Having the O/D off has a added advantage of a little bit of speed when accelerating.. but after 60, it is to switched off...

i am not sure about the technicality relating to O/D but porkster says it is a different gear in it's own.. i think he would give a MUCH better descripto about it...

Zz

yo! a link 2 clear ya doubts buddy....

http://www.faqfarm.com/Q/What_are_the_uses...ould_it_be_used

Zz

[streetKIA]

Lets not forget better fuel economy with O/D on. I have it on my rio, and i leave it on all the time. Aren't you supposed to keep it on always as long as you're below 75 km/h and not the other way about?

Edited September 19, 2006 by streetKIA

[noaim]

Dont get me wrong i do know what OD is all about, its jus that explaining to others is kinda tuff, now i can use the info above.. ty!

[neXGen]

ado! this is copyrighted work.. i need ROYALTY payments!!!! lolz..

Zz

[isurujosh]

ado! this is copyrighted work.. i need ROYALTY payments!!!! lolz..

Zz

i dont have OD all i have is D4-D3, so i thot having OD "On" is to let 4 gears shift and having it "Off" is to let 3 gears change

[The Don]

If I am not mistaken its a method of extending beyond the gear ratios provided by the automatic transmission box,

I think more information Can be found on this link

http://en.wikipedia.org/wiki/Overdrive_%28mechanics%29

I am not sure how the City D3 and D4 works but from the little I know about Automatic transmissions is it not a case of if you are in D3 gear changes only occur between 1-3 and if you are in D4 gear changes only occur between 1-4 ?

If you have OD it would be like having a virtual 5th Gear.

Regards,

The Don

Edited September 19, 2006 by The Don

[neXGen]

thanks for the added info Don! I switch O/D on n off as necessary.. though what i used to do earlier when i needed a good engine braking was that i shifted to 2 (which is the only number there) so that the engine would brake along with me hittin the metal... I seriously didnt know about all these gears blah blah... but then my pal adviced it ll wear down the transmission and it ll go bust.. so O/D was the NEXT BEST thing for me.. though it has a small effect at times..

Zz

[Elvis_Pil]

If I am not mistaken its a method of extending beyond the gear ratios provided by the automatic transmission box,

I think more information Can be found on this link

http://en.wikipedia.org/wiki/Overdrive_%28mechanics%29

I am not sure how the City D3 and D4 works but from the little I know about Automatic transmissions is it not a case of if you are in D3 gear changes only occur between 1-3 and if you are in D4 gear changes only occur between 1-4 ?

If you have OD it would be like having a virtual 5th Gear.

Regards,

The Don

Dude I'm not sure but I think the City has CVT.. no specific gear ratios therefore.

On my old van o/d would engage 4 low gears and when od's off it would be three high gears.. For city driving you would therefore need have the o/d off

However on newer cars it seems to be the other way around for instance the p11 and p12 primera's hyper CVT uses a 'sport mode' insted of o/d

[fuzzo]

funny thing is that in my mazda, it has a button on the gear shift. when i press it, the light on the dashboard reads "hold" and not "o/D" as i expected.

[Elvis_Pil]

funny thing is that in my mazda, it has a button on the gear shift. when i press it, the light on the dashboard reads "hold" and not "o/D" as i expected.

Yeah I've seen that on Mazda and Lazers.. it gives you 3 tall gears.. and you car comes non-cvt right?

[fuzzo]

yup it is non cvt

[Duncan]

It's basically to do with gear ratios and how soon you want the tranny to make the gear changes.

I would suggest having the o/d on all the time, whether it be city driving or long distance driving. Take the o/d off when you want to maximise the power range throug the gears.

[Hola]

Ok, in simple terms with all due respects for the current trend of petrol price hikes this is the conclusion..

OD OFF - Drinks Petrol

OD ON - Saves Petrol

Correct me if I am wrong

[Duncan]

you got that right bro!!

[neXGen]

negative.. i remember that proper usage of the O/D would made the engine last longer.. and SAVES petrol.. atleasts that is what i read.. basically 0-60 (within city) O/D off.. over 60 (highway) O/D on.. it has somethin to do with the shifting of the gears internally and when climbing a mountain or a hill terain the O/D being off would enable the engine to select the more appropriate gear ratio.. else it would be shifting amongst all gears trying to pull the car up and thus wearing the engine down...

that is paraphrashed of what i read.. so effective using of the O/D would help to save petrol too...

about the Honda CVT - correct pilawoos.. i read somewhere on the net that the CVT engine does not have gears theoretically but basically somethin like a cone shaped device with a belt going around it.. the belt movement position is decided by the engine depending on how fast you wanna go.. i dont know about mazda and the rest though...

newer cars probably would not be having O/D

Zz

[isurujosh]

i read somewhere on the net that the CVT engine does not have gears theoretically but basically somethin like a cone shaped device with a belt going around it

my self know very little about trannies! on the subject of CVT on honda city(new one) ... i have seen dat itz claimed to have 7-speed? how does the 7-speed claim fit wit the above quoted statement?

[The Don]

Isuru, go to howstuffworks.com and read up on CVT if you are interested, don't know if the City has CVT though, but basically if it does, it doesnt have set gear ratios and the gears change seamlessly between the highest and the lowest gear ratios depending on velocity and power exerted on the tranny

If you feel the gear change, its possibly not CVT

The Don

[neXGen]

Not sure about your quote about the 7-speed thingy dude.. but CVT does NOT have physical gears but i guess virtual gears do exist.. i just confirmed it.. but as i said something like a cone-shaped device.. am not very sure bout how the gears shift though..

check out the site Don said.. i think i read it from there :-)

Zz

[Elvis_Pil]

Not sure about your quote about the 7-speed thingy dude.. but CVT does NOT have physical gears but i guess virtual gears do exist.. i just confirmed it.. but as i said something like a cone-shaped device.. am not very sure bout how the gears shift though..

check out the site Don said.. i think i read it from there :-)

Zz

Its a 7 speed alright.. thats a fact. It must contribute to the car's good economy

[tuk tuk]

To put it VERY simply:

Overdrive ON = Gears shift at lower revs (and an extra gear become available)

Great for highway crusing, and puttering around the neighbourhood as the engine consumes less fuel. (The engine revs less and changes gears more often).

Overdrive OFF = Gears are held for longer (and last gear gets locked out)

Gears shift at higher revs allowing you to stay at the optimum rev limit longer. Great for decents (better engine braking), climbs, towing, and 'wanna be' racers wanting to make as much noise as possible when making those quick, furtile, bursts of speed between traffic lights. Acceleration is usualler quicker as the engine in the optimum rev range for longer (this being said some cars simply get louder and burn more gas). However you'll consume more fuel and increase engine wear and tear beacuse you'll be at higher revs more often.

I agree with Duncan with regards to the use of Overdrive. I generally leave the Overdrive ON all the time unless I'm desending a fairly long incline and can't be bothered feathering the brakes.

Btw speed junkies: Most cars only hit their top speed with the overdrive ON. (quickest way to top speed is to leave the overdrive OFF, until you hit 120-130 and then to turn the overdrive ON).

Edited September 20, 2006 by tuk tuk

[Newbi]

My cars (Toyota Verossa - RWD) got a power and snow button....Always thought the snow was to reduce slip and the power button when on delayed the gear shift...what do you guys think ?....Do you think the Power button is the same as the O/D ?

Cheers

[Nozozo]

regarding CVTs, 7 speed mode would enable the driver to down shift (with a button) specially when you want to accelarate. Ratio is determined by the software. It gives a manual feeling in A/T.

City brandnews do not come with 7 speed mode, but not sure the '06 model. Thai or singapore recons got this feature.

Edited September 21, 2006 by Nozozo

[isurujosh]

regarding CVTs, 7 speed mode would enable the driver to down shift (with a button) specially when you want to accelarate. Ratio is determined by the software. It gives a manual feeling in A/T.

City brandnews do not come with 7 speed mode, but not sure the '06 model. Thai or singapore recons got this feature.

yeap datz wot i have heard too!

My cars (Toyota Verossa - RWD) got a power and snow button....Always thought the snow was to reduce slip and the power button when on delayed the gear shift...what do you guys think ?....Do you think the Power button is the same as the O/D ?

Cheers

i think ur power button is something like the "M" button in a BMW M5

but i am not sure whether "delaying" the gear shifts (as u've said) z wot it does? to stay in the power band u need short shifts right? (not sure)

[Newbi]

yeap datz wot i have heard too!

i think ur power button is something like the "M" button in a BMW M5

but i am not sure whether "delaying" the gear shifts (as u've said) z wot it does? to stay in the power band u need short shifts right? (not sure)

Correct me if I am wrong shouldn’t the gears shift when maximum output is achieved at the right RPM. If the gears shift before wouldn’t it be a waste of something or the other. If the RPM is too high then it still would be a waste as the car would not be moving any faster.

This is where I got the idea that when the power button is on the gears will wait tile the maximum useful RPM is reached before it changes.

When the Power button is off the gears would shift faster at lower RPM there by not put any strain on the motor and conserve fuel.......

Isuru what does the M button on the BMW M do ?

Come onnn experts.....I know you guys are out there....give me your take on the matter........

If it seems like I am H/J thread I apologize and feel free to have the Mods delete this.

Edited September 21, 2006 by Newbi