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Discussion Starter #1 (Edited)
Hey compadres,

I've been thinking of changing gears on my "03' 4 SPEED AUTOMATIC".
This is my weekend car now and never take it to the track or strip. I only have some clean fun killing imports. I have install some light mods like;

*Ford Racing Headers, Raptor Mufflers, Pulleys (not sure what kind, that was 6yr ago), Superchips, BBK 78mm Throttle Intake, intake spacer, K&N cold Air Intake.

The car feels very strong, but I'm sure I can unleash a little more HP. As it is at 70MPH is running about 2150 RPM or somewhere around there. Which gear should I go with that is not going to Rev up the car too much but will make it more fun to drive?

All suggestions are very appreciated.

Thanks
 

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you wouln't even feel 3.73's in an auto, 4.10's plus or best to just leave it alone. don't forget a tuner/tune as you don't even want to move an auto car with a gear swap & not adjust the ECM for it.
 

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damn casper never thought of that^ does the computer get ****ed if you change the gears without being tuned for it? How would that work?

+1 for 410's
 

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Discussion Starter #4
you wouln't even feel 3.73's in an auto, 4.10's plus or best to just leave it alone. don't forget a tuner/tune as you don't even want to move an auto car with a gear swap & not adjust the ECM for it.
when you say tuner, Is there a specific one that I should use?
I think I can change the gear ratios with my Superships Tuner (don't quote me on that) it's been a loooong time since I've used it.
 

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get a SCT xcal 3. you'll be good!
 

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Discussion Starter #7
ReverendDexter

I was told that gears help getting more HP to the rear wheel and that it make the car quicker. is that how it works? I'm a virgin with gears!!!
 

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ReverendDexter

I was told that gears help getting more HP to the rear wheel and that it make the car quicker. is that how it works? I'm a virgin with gears!!!
he's right that it doesn't add power, it just make's you feel/be able to use what you have in a diffrent spot.
 

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damn casper never thought of that^ does the computer get ****ed if you change the gears without being tuned for it? How would that work?

+1 for 410's
not so bad on a stick car, just messes up your speedo/odometer for the most part. the o/p is an auto & auto's use the VSS to operate the trans, absolutely must adjust for the gears in an auto.
 

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ReverendDexter

I was told that gears help getting more HP to the rear wheel and that it make the car quicker. is that how it works? I'm a virgin with gears!!!
No, if anything you actually lose rear wheel hp by going to lower gears (maybe 1-2 hp).

What you're feeling is the effect of leverage. Think of it this way - if you have stock gears, say 3.27s, that's like using a 3 foot, 3 inch long breaker bar on a lug nut. To go to 4.10s would be like grabbing a 4 foot, 1 inch long breaker bar. You're not any stronger, but the longer bar lets you bust that lug nut a lot easier.

If that image doesn't work for you, you can also think in terms of effective torque. Multiply the engines crank torque by your final drive to get your effective torque in 4th gear (direct drive). Assuming you have 260 ft-lbs of torque with stock gears, that's 850 effective ft-lbs at the tires. To go to 4.10s, you'd have 1066 effective ft-lbs. If you're geared down via the transmission, you have even more - say you've got a 3:1 1st gear, that means with 4.10s you'd be pushing almost 3200 effective lbs of torque through your rear tires! This is how a motor with 300 ft-lbs of torque, with enough traction, can lift the front end of a three thousand pound car.
 

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+1 Very good explanation. I like your breaker bar example.
 

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Wished my car was done.
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No, if anything you actually lose rear wheel hp by going to lower gears (maybe 1-2 hp).

What you're feeling is the effect of leverage. Think of it this way - if you have stock gears, say 3.27s, that's like using a 3 foot, 3 inch long breaker bar on a lug nut. To go to 4.10s would be like grabbing a 4 foot, 1 inch long breaker bar. You're not any stronger, but the longer bar lets you bust that lug nut a lot easier.

If that image doesn't work for you, you can also think in terms of effective torque. Multiply the engines crank torque by your final drive to get your effective torque in 4th gear (direct drive). Assuming you have 260 ft-lbs of torque with stock gears, that's 850 effective ft-lbs at the tires. To go to 4.10s, you'd have 1066 effective ft-lbs. If you're geared down via the transmission, you have even more - say you've got a 3:1 1st gear, that means with 4.10s you'd be pushing almost 3200 effective lbs of torque through your rear tires! This is how a motor with 300 ft-lbs of torque, with enough traction, can lift the front end of a three thousand pound car.
+1

Excellent post
 

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+1 for 4.10's, if I had an auto I'd consider 4.30's lol
they don't add power but shifts your torque band so you can get more low end.
For an auto you will need a tuner to correct the speedo and shift rpm for the the gears so that the car doesn't just shift randomly

keep in mind that you can always offset a steeper gear with taller tires :)
 

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yeah, get some 4.10's or nothing!! dont fear the gear....youll love the 4.10's. later youll regret not getting them!!
 

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:)

4.10s in my car was like the feel i got from putting the blower on my car :)
 

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Discussion Starter #20
Thank you Everybody for your help, Specially ReverendDexter for that great explanation. I think I will go with the 4.10's.

asiansensation78, you also made a good point. I'm putting bigger tires on the car to help offset the steeper gear.
 
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