Is it bad to drive with the over drive on? Or off? And does it save gas to drive with it off? I would like as many answers as possible...just for accuracy.
2007-10-24 04:53:42 · 10 answers · asked by just james 3 in Cars & Transportation ➔ Maintenance & Repairs
changes the gear ratio in the transmission so that your wheels actually turn faster than your engine. The down side to overdrive is you don't have the power you do in the lower gears. Overdrive works best on highways . as long as you are not towing anything.
2007-10-24 05:01:45 · answer #1 · answered by Anonymous · 0⤊ 0⤋
*An overdrive transmission works like this weather it's a standard or automatic. As you know your transmission has many gears it shifts through depending on load, speed and incline.
When you move form a dead stop the car moves first in low gear. To make this really clear I'm going to refer to a Tremec standard six speed manual transmission.
Low gear is 3.36 to one ratio. This means for every 3.36 rotations of the crankshaft, the output shaft of the transmission and driveshaft turns once.
I'll include all the gear ratios of the Tremec #1386-000-006 transmission we are talking about.
First gear 3.36 Second gear 2.07 Third gear 1.35 Fourth gear 1.0 Fifth gear .8 Sixth gear.62
Let me clarify fourth gear. For every turn of the crankshaft inside of the motor the output shaft and drive shaft are turning at the exact same speed therefore 1.0
Now is where the two over-driven gears come into play.
In fifth gear the gear ratio is .8. That means the output shaft of the transmission is turning .8 times faster than the crankshaft Sixth gear is turning the driveshaft .62 times faster than the crankshaft.
In this particular transmission fifth and sixth gears are overdriven
In your particular case it's best to leave tour gear selector in drive and let the transmission use all the gears including overdrive. It's to your advantage to let the motor run at the lowest RPM possible all the time to save fuel.
There are cases when it's adviseable to use the lock-out overdrive button. If you are driving up a steep hill or pulling a heavy load the transmission will not be constantly shifting or hunting for a higher gear.
Not to add more stuff to the equation but the rear end center section has a ring and pinion gear depending on the number of teeth on each of the gears determinines what's called the final drive ratio. For instance If the rear end is a 3.73 ratio, the driveshaft turns 3.73 times to one revolution of the rear wheel.
2007-10-24 06:04:50 · answer #2 · answered by Country Boy 7 · 1⤊ 0⤋
Overdrive is used to make your car get better gas mileage by making the engine run at lower RPM. I leave the overdrive on all the time. If the car needs more power the transmission will down shift, it's all automatic that is if your transmission is automatic.
2007-10-24 05:10:38 · answer #3 · answered by Dana 4 · 0⤊ 0⤋
what overdrive does is that it lowers a gear so you can get more power while trying to pass a car,going into a hill or when you have a load not to over heat your engine and transmission,it also helps your car not to strugle...it is possible for the car to waste a lil more gas if you tun it off if driving normally,but it helps when having a heavy load
hope this helps
2007-10-24 05:11:36 · answer #4 · answered by thes 2 · 0⤊ 0⤋
it doesn't so much "drop your rpm" as it acctually provides a overdriven final transmission ratio. vehicles without overdrive have a final ratio of 1 to 1, meaning that for every time your crankshaft turns, the main gear shaft in the tranny matches it. with a overdriven trany, it changes so that it turns faster than your crankshaft. in turn "dropping" your RPMs. all late model cars with electronic overdrive can be driven at all times with the overdrive on. where you might want to disengage it would be if you were going up a steep hill and you felt the vehicle "bogging down" or going down a steep hill and shifting out of it to help control your downward speed. 99.99% percent of the time you can leave it on and forget about it.
2007-10-24 05:12:41 · answer #5 · answered by bigbearduff 2 · 0⤊ 0⤋
It lowers your engine's RPM on the open highway which saves gas. But when the engine is "lugging" (straining), shift to normal drive to increase engine RPMs like when going up a steep hill.
"OverDrive ([D], OD, or a boxed D) - This mode is used in some transmissions, to allow early Computer Controlled Transmissions to engage the Automatic Overdrive. In these transmissions, Drive (D) locks the Automatic Overdrive off, but is identical otherwise. OD (Overdrive) in these cars is engaged under steady speeds or low acceleration at approximately 45mph (72 kph) The transmission automatically downshifts at a speed of approximately 65 mph (104 kph), or under hard acceleration."
2007-10-24 05:00:02 · answer #6 · answered by bobweb 7 · 0⤊ 2⤋
Think of it as a 12 speed bike... The faster you get and change gears you dont pedal as hard you dont burn as much energy...and so on....so likewise your car should be in overdrive to save gas and to save trans wear, unless your are towing.
2007-10-24 05:17:51 · answer #7 · answered by Daniel G 2 · 0⤊ 0⤋
Slows engine RPM. Usually sets the transmission final drive ratio to about 1 to 1. By slowing engine RPM, you increase fuel economy. This is usually at the cost of power and throttle response.
2007-10-24 04:59:04 · answer #8 · answered by Mad Jack 7 · 0⤊ 1⤋
in the tranny , it means,
the input shaft turns slower than the out put shaft.
ie: the output is over driven.
4th gear is 1 :1 , OD is .75 to 1 or the like.
2007-10-25 18:41:43 · answer #9 · answered by gearhead 2 · 0⤊ 0⤋
Ok, basically what happens when in over drive, is that the flux capacitor kicks in and then once the car hits 88mph, you will see some serisous ****.
2007-10-24 05:22:13 · answer #10 · answered by Anonymous · 0⤊ 0⤋