overdricve or drive?

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i have a qeustion, ok yesterday i raced my friends 1995 manual eagle talon with headers and coldair intake,and i had my friends 1992 eclipse auto and headers and coldair intake,ok he won buy about 1 car length i had my car in Overdrive, could this be the difference? doesnt matter? should i have manually shifted? please help i want revenge

posted by  talongod33

the purpose of overdrive is mostly for fuel economy for example your crank will spin .7 times to 1 of the trans output shaft. to answer your question yes it would make a difference but your RPM will raise higher and if you don't keep an eye on them you could damage your engine.

posted by  carlos

Carlos, How would the RPM be raise higher in overdrive. You just said that the engine speed will spin .7times to 1 time of the driveshaft. Wouldnt this make the RPMs lower than driving without overdrive?

posted by  CarEXPERT

his question was will racing his friend again w/out the OD make a difference and my answer was yes but the RPMs will increase sorry if i confused you

posted by  carlos

Yes it will make a difference if you put it in overdrive because the RPMs will LOWER not faster. I think you mean "but the RPMs will decease"

posted by  CarEXPERT

ok think of it like this when an automatic shifts up the RPMs drop don't they?OD is usually the last gear of a trans(at least automatics, 6speed manuals USUALLY have two OD) so by not using OD and shifting manually your trans will never shift up therefore your RPM will keep increasing until you shift up or let off the gas. hope this helps don't know how else to explain it

posted by  carlos

"OD is the last gear of the trans"-Carlos. Why would you want to use OD when you are racing becaaue OD gear is the gear with the lowest engine speed and in racing you want high engine speed.
Like you said OD is for freeways for fuel saving because it makes your RPM slower.
You can shift manually in an automatic cars. I've done this. But it really doesnt make a diffrence because autos shift at redline anyways. When you manualy shift while full throttle it will shift at redline too and this is what you want for racing. On OD gear under full throttle, it will be much longer for the RPMs to reach redline than on regular. Did I get anything wrong here carlos.

My friend at school said that his VW Volvo an old one had overdrive and he uses it to go up incline roads because its more powerful than regular gear. Is this true, I tried to prove him but he says that OD is mostly for going up hills or inclines.

posted by  CarEXPERT


posted by  CarEXPERT

i'm going to have to disagree with your friend on this one, when going up a hill what you want is more torque to get the weight moving. you can only do this on a low gear like first or second in which toque is multiplied the greatest. just like when you try to move a manual in third or fourth gear you'll stall out due to lack of torque to move the weight.

posted by  carlos

VW volvo eh?

posted by  BanffAutoSpa_ap

I have a 94' Talon ES w/ an automatic tranny. My tranny went out of it awhile ago, and i was wondering if i would be able to drop a 5-speed in it that came from another talon with the older body style (89-92)? Also, would i need to take the wiring harness from that Talon and switch it over to mine?

posted by  Talon_05

Jesus! Learn to READ! The original question was asking if leaving it in OD cause him to be slower. Carlos said leaving it OUT of OD will make it quicker but it will increase RPMs. Carlos was saying NOT to use OD in drag racing, and you keep arguing with him! STFU!

[pquote]Like you said OD is for freeways for fuel saving because it makes your RPM slower. [/quote]

THAT'S WHAT HE SAID! Carlos said repeatedly that the rpms would be higher by NOT shifting into OD!!! How dense ARE you?

Yes, you did. The trans will shift when vacuum or internal controls say to shift, which MAY NOT BE where you want it, depending on the actual car you're in.

[/quote]My friend at school said that his VW Volvo an old one had overdrive and he uses it to go up incline roads because its more powerful than regular gear. Is this true, I tried to prove him but he says that OD is mostly for going up hills or inclines.[/QUOTE]

That's entirely backwards. You shift DOWN to go up inclines and hills. There is less mechanical advantage in the taller gear ratio, so it's putting down less torque to the ground in OD.

posted by  ChrisV

Thanks for correcting me Chrisv. I have this little question I want to ask you. In a stick shift when you are in first gear and pressing on the throttle, then when you let go of the gas the car jerks foward. Is this because in first gear the engine and trasmission speed are the same speed? In general in first gear, Does the engine speed spin more than the transmission speed or what?

posted by  CarEXPERT

Actually, the car doesn't jerk forward. YOU do in the car. the car itself slows down dramatically. When you let off the throttle, the reduction in engine speed acts like a brake, as the ground has more mechcanical advantage on the tires than the engine does, slowing the car. In first gear, you're not going very fast, so it slows down much faster than in higher gears.

The engine speed and the input shaft on a manual transmission spin at the same speed when the clutch is engaged, regardless of the gear you are in.

If the engine is turning 2000 rpm, then the input shaft on the trans is turning 2000 rpm. the OUTPUT shaft on teh trans, going to the differential, is rotating at a rate of the engine rpm divided by the gear ratio (in first gear, that's usually 3.0-3.5:1) thus at 3000 rpm engine speed and a 3.0:1 first gear ratio, the input shaft is turning 3000 rpm, and the output shaft is turning 1000 rpm. Of course, then as the output goes through the differntial/final drive, the shaft speed is reduced again by THAT ratio. Using the previous engine speed and first gear ratio, and a 4.10:1 final drive ratio, the wheels would then be turning at just under 250 rpm. if you know the circumference of the tire at that point, you can tell how fast the car will be travelling at 3000 rpm in first gear.

posted by  ChrisV

Is what you said with the losses of rpm true for both RWD and FWD? Because your example was a RWD right? so is that the same with a FWD because the flywheel is at the side of the engine.

posted by  CarEXPERT

it's all the same. The parts are the same for both, only how they are arranged differs.

posted by  ChrisV

i couldn't finish reading all the other replys back and forth to each other. if you want to race your friend again then get to know your car under racing conditions. you will generate more rpm if you manually shift. you might want to start in 2 instead of 1, listen to motor and shift to drive once you have reached the point where you think you have got the most out of the geer.again listen to motor.and once you have reached 55 to even 75 shift into overdrive to prevent over rev, and you might even get to kick in a passing gear :wink2: good luck and remember you could harm your motor or tranny by racing it, so if you dont have a back up car or plan then think twice before you send your car to the shop becouse you wanted to out race a friend :banghead:

posted by  donaldnjamie

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