overdrive

[charlski]

Hi there
can anyone tell me should i have the overdrive on or off when driving on the road

Thanks

[Gamedawn]

Generally speaking it should be on because this allows the torque converter to lock up and gives the best economy. You should turn it off it situations like towing, climbing hills, etc where the transmission could be changing up and down all the time.

[charlski]

cheers for reply........... i thought so ..........but conversation in pub in kettering today, freind of mine was saying it should be off all the time except for motorway driving.

[parn]

jeez im soooo noob i been driving my surf for a week with it off thinking my fuel consumption would be better ... im wrong arent i?

[da SLUG man]

cheers for reply........... i thought so ..........but conversation in pub in kettering today, freind of mine was saying it should be off all the time except for motorway driving.

he's probably thinking of the type fitted to a manual motor back in the 70s

[Robb.]

jeez im soooo noob i been driving my surf for a week with it off thinking my fuel consumption would be better ... im wrong arent i?

yes, it technically gives you another gear hence lessening the revs

[exmee46]

A diesel engine is particularly suited to use with an overdrive since it has a nice flat torque curve that peaks at relatively low revs. This is particularly true of the 3lt Surf engines. A highly tuned petrol engine where the torque comes in at much higher revs would be sluggish using overdrive at low revs and so woudl probably only use it for cruising on motorways etc - so your pal wasn't entirely wrong.

So use the overdrive almost all of the time ( a lot of people tow with it as well). There is perhaps a case for switching it out in town to prevent excessive slip in the torque convertor caused by the slow road speed which wastes energy and fuel.

The other benefit of the overdrive is that it also enables the lock-up above 54mph which removes the torque convertor losses altogether (effectively a 5th gear). This does not happen with O/D off which only gives you 3 gears.

Cheers

Kev

[Guest]

I find I get better economy if I switch the O/D off around town as the engine is labouring less. It's a myth that Diesels like running at low revs, it's best to keep them above 16-1700rpm as it has to do less work then to pull the car (especially on a 2.4 which has less power than the 3 litre. Once I am consistently doing more than 40mph O/D goes on.

Cheers