Thursday, April 13, 2006 - 11:27 am, by: David Vaughan(Davidv)
^^ What Daniel said, and do not worry about the engine; it will look after itself, unlocking the torque converter clutch in 4th or changing down as required.
Hahaha, I guess if you like pressing buttons so much... It really is useless doing that though. O/D doesn't change anything about the shift pattern or anything else from 1st to the 3rd gear, apart from the fact that it will shift up to fourth from third when necessary. Put it another way, it's like having the following positions on your gearstick P R N D 3 2 L, and no O/D button. All you are doing is just putting it in the 3 position as opposed to D by having O/D switched off.
Ok. O/D should be ON all the time for normal driving, all it does is shift the gear from 3rd to fourth when revs get too high, if revs are still reasonably low while in third it won't shift even though O/D is on (just like if the revs were reasonably low in second, it wont shift to third). This is also the reason why the light comes on when the O/D is off, because then it is an unusual situation, so it alerts you of that. (you'd like to have the least amount of distracting lights on the dash normally, therefore light is off if O/D is on.)
As for switching the O/D off, you'd only do it for the purpose of engine breaking. So if you are towing a boat, and you are going down a long hill, you don't want to go too fast, and you don't want to be applying brakes all the time (you don't want them to overheat, fade, wear off, whatever) you put the tranny back from fourth to third gear by switching O/D off. That way, no need to use brakes, the engine keeps a reasonably steady speed downhill. Does that make it clear now?
EDIT: And if you are towing a boat on a flat road, you probably won't need the engine braking effect, unless it's really heavy, so you have O/D on.
Thursday, April 13, 2006 - 01:06 pm, by: Matthew Sharpe(Madmatt)
Its just a "top gear" so if you have it on, your car will run at lower revs, thus saving fuel and wear.
Technically an overdrive is a unit that bolts on to the tail of a transmission using a solinoid activated clutch to engage and thus alter the output ratio of the gearbox - but as I recently discovered, this is not what it is on a Soarer - on the Soarer it really is just a 4th gear that you happen to be able to switch on and off. Might as well leave it on and save fuel and wear on the car if you're not like me and dont like switching it on and off as required.
Thursday, April 13, 2006 - 01:16 pm, by: Peter Nitschke(Pen)
Perhaps think of it as Enabled/Disabled rather than On/Off. If it's Off (Disabled) then it can't be used, if it is On (Enabled) then the car can use it when it decides it is beneficial to use it.
Thursday, April 13, 2006 - 02:32 pm, by: Samantha Hornby(Marla_singer)
I never use mine. I find the wooshing air sound really annoying and I just end up with one sunburnt shoulder. I usually open the passenger window if I want a little fresh air.
Yeah Sam, you're pushing the limits here, even by my getting-sidetracked-offtopic-ability standards Either that, or I want the same thing you're having
David Vaughan Goo Roo ACT UZZ31 V8 manual and Lexus IS300
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has this got to do with OD or petrol? 
Either that, or I want the same thing you're having 
