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OverDrive

negatron

By negatron
in Corolla / Corolla Sportivo Club

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negatron Grand Master

negatron

Posted
Posted

Hey all,

Can someone tell me what exactly is overdrive in autos?

Is it a physical 4th gear?

A ecu setting?

rolla02 Experienced

rolla02

Posted
Posted
Can someone tell me what exactly is overdrive in autos?

Is it a physical 4th gear?

Same as in a manual Gearbox.

It means the output shaft of the Gearbox is turning faster than the Crankshaft (or input shaft of the Gearbox)

In the first 3 gears (lowest gears) of the auto 'box the crankshaft is turning faster than the output shaft.

Most manual boxes are overdriven in 5th or 5th and 6th if you have a 6 speed.

Pippy Mentor

Pippy

Posted
Posted (edited)

Why not try it and see what it does? :D

Overdrive it not really a physical gear, personally speaking...

I doesn't give you more power, as the term has been wrongly used... e.g. "Lets shift into OVERDRIVE"

Overdrive allows your car to at lower revs (at idle revs) when you're driving at cruising speeds... notice how if you have overdrive on at say 100km/hr, the revs will only be at about 2000rpm, but if you accerate to overtake or something, the revs kinda jumps up to about 3000rpm, and makes a sound similar to someone doing a bad shift on a manual car, hence without overdrive the revs stays up.

You can think of it as crusing at almost neutral, to save fuel of course. :)

donno if i got the wording right... but its too early... anyway... :blink:

peace

Edited by pippy
Pippy Mentor

Pippy

Posted
Posted

How overdrive works

The overdrive consists of an electrically or hydraulically operated epicyclic gear train bolted behind the transmission unit. It can either transfer the input drive shaft directly to the output shaft, called a propshaft (1:1), or increase the propshaft speed so that it turns faster than the input shaft (1:1 + n). Thus the propshaft may be "overdriven" relative to the input shaft. It is actuated by a knob or button, often incorporated into the gearshift knob, and does not require operation of the clutch.

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


Romp Veteran

Romp

Posted
Posted
Thanks for that link pippy.

At times like today, you wouldn't wanna turn it off.

i tried it today

i push the button and "O/D off" lights up

basically i was going 110km/h and i hit it and it felt as though i down shifted.

The revs shot up from 2k rpm to 4k rpm and felt the engine braking the car ...

it held my speed back to about 80-90km/h. The benefit would be to push this to have higher revs and then accelerate off having higher revs to play with

or goign down a hill hit the o/d button and u need less brakes and just use the gear to slow u down

Buddha Grand Master

Buddha

Posted
Posted

For all intents and purposes, I treat overdrive as a 4th gear. Personally I find it easier to think of it that way, because that's the way it behaves.

Some Rollas in Japan use the same transmission but have one of those "jagged" transmission selectors, with 1, 2, 3 and Drive, rather than our 1, 2, Drive and switch.

shaohaok Grand Master

shaohaok

Posted
Posted

those that have the dogleg shiftgates have a different autobox.

it's called the superECT transmission. supposedly more intelligent in that it will know that the car is going uphill and downhill; and therefore select the appropriate gear. it WILL know to select and hold 3rd or 2nd when u are descending.

Buddha Grand Master

Buddha

Posted
Posted
those that have the dogleg shiftgates have a different autobox.

it's called the superECT transmission. supposedly more intelligent in that it will know that the car is going uphill and downhill; and therefore select the appropriate gear. it WILL know to select and hold 3rd or 2nd when u are descending.

I sit corrected ... and jealous :P

shaohaok Grand Master

shaohaok

Posted
Posted

forgot to add, it shifts quicker and smoother, too :P

it's quite cool with those merc style shiftgates. u can get some really nice gearknobs for them and u just swap them like manual shift knobs.

Nino_Leb Mentor

Nino_Leb

Posted
Posted

overdrive is an engine braking system,also as some may say it doesnt give more power it really does.Try going over 120 with your car and watch it struggle.enable overdrive and i have reached 180 which is that cars top speed as it was overrevving and unable to pass that point.

Buddha Grand Master

Buddha

Posted
Posted
forgot to add, it shifts quicker and smoother, too  :P

it's quite cool with those merc style shiftgates. u can get some really nice gearknobs for them and u just swap them like manual shift knobs.

OK, OK, I'm green enough with envy! Please no more! :P

negatron Grand Master

negatron

Posted
  • Author
Posted
*removed*

HAhaha Brandon u didn't post about that incident involving the Apexi did you? :lol:

BigBum Grand Master

BigBum

Posted
Posted
*removed*

HAhaha Brandon u didn't post about that incident involving the Apexi did you? :lol:

nah... i said top speed in auto 1zfe isnt 180, but realised he didn't mention anything about doing 180 in a 1zfe.

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