When does a car use overdrive?

Answer 1

Usually at about 40mph or above. At cruising speed, when not passing or accelerating.

Answer 2

Hi, I used to own an MGB which had overdrive on 3rd and 4th gears. Overdrive third was great when I need a bit more power eg. to overtake and car doing around 45/50 mph; I could drop down to overdrive 3rd. and get passed it more quickly. Overdrive 4th. is for cruising at higher speeds, for instance on the motorway, duel carriageways and the open roads. The best way to use overdrive is to drive by the rev counter rather than the speedo, (although you have to be award of your speed at all times). I tried to keep the revs between 2500 and 3000 rpm.
Hope this helps :)

Answer 3

Overdrive is not for power or accelleration, it allows the engine to run at a lower rpm at any given speed for more economical cruising (faster vehicle speed at lower engine speed, NOT quicker accelleration). For example instead of a 1:1 transmission ratio, overdrive may be 0.67:1 so the engine revs 1/3rd slower (2000 instead of 3000 rpm for example). Typically just high gear would be overdrive, but with a 6-speed, possibly 5th and 6th.

For an automatic OD transmission it is automatic. You might use the non-OD position or OD lockout button if towing a trailer, for engine braking going down a long hill, or possibly when scooting around town at low speed if experiencing frequently downshifts. For a manual transmission the proper gear to use should become intuative with experience (enough power without lugging the engine).

In the old days before overdrive transmissions were common, it was sometimes a separate device after the transmission or 2-speed rear end, which effectively changes all transmission ratios (heavy trucks may still have multiple rear end ratios).

Answer 4

An overdrive is an additional gear unit fitted after the gearbox or transmission, usually capaple of being switched in or out electrically. It allows it's output shaft which goes on to drive the wheels to turn quicker than it's input shaft from the main gearbox and engine, hence the term overdrive because the output shaft is overdriven compared to it's input.

A car will typically use ovedrive in when in it's top gear and in high speed cruise as a means of reducing engine revs and improving fuel efficiency.

Answer 5

Overdrive is a part of the automatic transmission that helps the torque converter (the part of your transmission that converts power from the engine into power the transmission can use) cool itself. When the transmission shifts into overdrive, the torque converter goes into what's called 'lock-up', meaning that it stops turning so it can cool itself and the transmission no longer is using it. When pulling heavy loads, traveling on rough terrain, or up steep inclines, turn your overdrive off, otherwise you could cause damage to the transmission! Otherwise leave it on. I does help your gas mileage on long trips, but then, cruise control does too. Be sure and have the fluids in your transmission changed every 30K or once a year if you live in a highly populated area with lots of traffic, otherwise every 50K or two years.


Midnight~Angel :)

Answer 6

Overdrive is controlled by the driver, not the car. There is a switch to turn it on or off. Usually only operates in 4th/3rd gear. Saying that, had a friend who modified the wiring so that could be used on all gears-including reverse.

Answer 7

Overdrive is a very misused term.

All it really means is the wheels make more than one turn for one revolution of the engine.

Automotive marketing departments have distorted the meaning into something completely different.

Answer 8

if its a old highly geared car like a sports car it will need overdrive for motorways, dual carriageways etc as the old sport gearboxes couldn't cope with long journeys like the new ones can

Answer 9

Over drive lowers revs and puts less work on the engine,so it is used mostly on motorways or long flat stretches of road.Its like a sixth gear on older cars.

Answer 10

Actually, in a nut shell. Your passing a car and you see the on coming traffic is getting close. Drop it into overdrive and give it enough gas to pass. Also if your towing a trailer and you need a little more power. drop that puppy into overdrive.I
guess that was a overdrive nut shell.LOL Peace...