Driving a auto in Overdrive bad?

[Leon.T]

just wondering would I damage my R33 if I drive in overdrive the whole time? Would it damage my gearbox or somethin? Trying to save petrol by driving in low rpm. god damn fuel price rise.

[SKY031]

uh....... doesn't overdrive make the revs go UP?

[strutto]

The OD button in a 33 disables 4th gear when unpressed (ie when the light on the dash goes on... The light incidently says O/D off)...

So no, overdrive doesn't make the revs go UP, but I understand where your coming from Karina...

Driving with the OD enabled (ie light off) won't cause any problems...

[T0nyGTSt]

Like most autos, OD off is pretty much de rigeur in normal 50/60 zoned urban areas.

Normal electric, quasi-hydraulic autos really do not have enough smarts to manage OD properly in urban driving.

Now high tech 'smart' 5 speed autos are something else...

T.

[Leon.T]

k thanx guys. But would it save petrol doing this? When I leave OD on (light goes off) the rpm drops to 1/2 of what I'm doing normally.

[WazR32GTSt]

i have an auto mate so this is coming from experience...

i only turn o/d on when i'm over 70km/h. reason? with the button pressed in the car constantly tries to drop to the highest gear. often with just the touch of the accelerator it can try to jump from 4th back to 3rd then into 4th again.

when you accelerate from low rpm in 4th gear you are placing a large load on the gearbox and this ain't the best.

easiest is to:

1) get a trannie cooler (i picked one up for $80 at supercheap)

2) leave o/d OFF in traffic

3) turn o/d ON when you hit a long road / freeway and are over 70km/h

good luck!

Waz.

[R31Nismoid]

yeah, OD is only for 70-80km or above.

You wear the auto out if you have it in OD at 50 i was told it wore out the box quicker due to the low revs or something.

Wonder if there is an truth to that statement or not.

[T0nyGTSt]

yeah, OD is only for 70-80km or above.

You wear the auto out if you have it in OD at 50 i was told it wore out the box quicker due to the low revs or something.

Wonder if there is an truth to that statement or not.

Not on Skylines but it was true on the early Turbo 700 automatic boxes on VN/VP Commodores.

T.

[Leon.T]

ok kool, thanx guys

[Rollin]

ok, short lesson in autos - they arent magic things.

"overdrive" just means any gear which when selected makes the output shaft on the gearbox spin faster than the input shaft (which is attached to the engine)

most 5 speed manuals have 5th as an "overdrive" 6 speeders have 5th and 6th overdriven as well.

so, if you wish to drive around with all 4 gears the gearbox has to offer, then leave overdrive on. if you dont, turn it off and the box will behave like a 3 speeder, allowing only 1st, 2nd and 3rd gears to be selected.

the benifit of allowing 4th to be used is better fuel economy, then benifit of turning it off is slightly better engine braking (saving your pads and dics very slightly) and less shifting through the gears if you are only driving at low speeds all the time, this in theory means your gearbox lasts longer and runs cooler.

the choice is yours, there really isnt a "right" and "wrong" way - just do what you prefer.

but yeah, get a big-ass oil cooler for your auto anyway, it would be the first mod i would do were i to buy an automatic car.

[red900ss]

I thought O/D on most auto boxes just locked the torque converter? no? :confused: