Myth or not?

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tama

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Dec 27, 2003

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San Jose, CA

Sep 1, 2005

#1

• Sep 1, 2005

• #1

Is it a myth that your fuel effeciency suffers as the result of going with 4:10 rear end differentials on your 4 valve? I need several responses and thoughts on this please.

 

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Uncle Meat

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Jun 13, 2002

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Prattville, Alabama

Sep 1, 2005

#2

• Sep 1, 2005

• #2

tama said:

Is it a myth that your fuel effeciency suffers as the result of going with 4:10 rear end differentials on your 4 valve? I need several responses and thoughts on this please.

Click to expand...

Well theoretically it should. Any time your engine RPM is higher at cruise speed will result in higher fuel consumption. For example, if the car was turning 2000RPM's at 70MPH with the stock gears and you swap those out for 4:10's your RPM's at 70MPH will now be higher. Higher RPM burns more gas.

U.M.

 

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Snakestress

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Jun 27, 2005

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Sep 1, 2005

#3

• Sep 1, 2005

• #3

true story, i just went from 3.27 to 4.10 in my 97 cobra. I used to get 20 mpg (i drive all highway). after the gears i got 21.5. seems like my mileage actually improved and i dont know why but im not complaining..

 

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tama

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Dec 27, 2003

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San Jose, CA

Sep 1, 2005

#4

• Sep 1, 2005

• #4

Well that's why I'm asking. I just want some experiences. I also feel my gas milage has had no effect...keep in mind I don't speed and travel about 70mph.


Unlees someone leaves the rpm reving a bit higher then normal instead of small simple shifts.

anyone else care to chime in please.

 

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chrisbudl1

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Dec 21, 2003

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springfield MO

Sep 1, 2005

#5

• Sep 1, 2005

• #5

mine totally depends on my foot. on average I get 180 miles out of 3/4 tank of gas. I have a pretty heavy foot, and drive 11 miles to and from work each day. atleast 5-10 blasts to 100 on average. I would say that if your talking strictly highway mileage, you will suffer, due to the rpm's, but you didn't get a four cylinder? I really don't see a major difference, it all depends on your foot!

 

a_k

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Nov 12, 2004

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Saratoga NY

Sep 1, 2005

#6

• Sep 1, 2005

• #6

Snakestress said:

true story, i just went from 3.27 to 4.10 in my 97 cobra. I used to get 20 mpg (i drive all highway). after the gears i got 21.5. seems like my mileage actually improved and i dont know why but im not complaining..

Click to expand...

Same thing on mine but mines a 95 gt but i think the odometer and spedo are fast even though i go the spedo gear changed. idk if mine is accually lower

 

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Uncle Meat

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Jun 13, 2002

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Prattville, Alabama

Sep 2, 2005

#7

• Sep 2, 2005

• #7

The reason why some people may say they now get better mileage with 4:10's is because they may not have gotten their speedo re-calibrated for the new gears. Now when they are going 70MPH they may really be going slower which would result in better MPG.

Another possibility is that people will tend to drive their cars a little differently after a gear install. Now that their car accelerates easier they don't need to mash the gas pedal all the way down to the floor in order to get moving. This results in better gas mileage because they are not lugging the engine as much.

At a steady 70MPH on the highway your 4:10's will get worse gas mileage than the stock gears and that's a fact. This of couse is based on someone running a whole tank of gas through the car on the highway. If you do a lot of stop and go city driving in conjunction with highway driving there may be a slight increase in MPG.

U.M.

 

missouri_guy197

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Aug 31, 2002

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St. Louis, MO

Sep 2, 2005

#8

• Sep 2, 2005

• #8

It's all in how you drive after the gears too...4.10's allow easier 2nd gear starts from stops too so you'll get some improved gas milage there possibly...And remember, although the engine is spinning faster, the numerically higher gears allow the engine to run easier due to the mechanical advantage, or it'll be able to do more work with a similar amount of effort...It also has to do with the amount of time the car spends in vacuum too...

Mainly on how you drive though...I've gotten similar, albeit not good, MPG with the 4.56 as I did with my 4.10's...that is if I keep my foot off the happy pedal, which isn't very much when I drive it now...

 

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Snakestress

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Jun 27, 2005

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Sep 2, 2005

#9

• Sep 2, 2005

• #9

i got my speedo recalibrated and im only 1mph off. I drive about 40miles a day to and from work. I drive the same speed i always do, on cruise control (67mph) and actuall i sometimes drive faster than i used to because i cant help myself. I do find myself shifting less and shifting earlier than 3000 rpm. It might have helped a lil bit. I drive all highway as well. I dont know why im getting better mileage, but it could be one of many factors. Regardless, im not seeing my gas mileage "suffer" from the gear swap. Even if you do, it wont make that much of a difference based on personal experience.

Try it and see how it works for you. Even if you get 3mpg less, to me it's still worth it. The positive imo far outweigh the negatives. If you really care that much about gas mileage, you might consider getting a beater.

on another note, most lightning owners get better gas mileage from 4.10s

 

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tama

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Dec 27, 2003

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San Jose, CA

Sep 2, 2005

#10

• Sep 2, 2005

• #10

I have 4:30's and don't car about gas milage. The reason I asked is because I'm curious. I have hear some people say yes and some people say no.

I don't know? So I asked

 

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Uncle Meat

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Jun 13, 2002

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Prattville, Alabama

Sep 2, 2005

#11

• Sep 2, 2005

• #11

Well explain to me why Ford doesn't install 4:10's at the factory if they are so great for gas mileage? It would raise their overall C.A.F.E. ratings which would be better for the company overall.

U.M.

 

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tama

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Dec 27, 2003

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San Jose, CA

Sep 2, 2005

#12

• Sep 2, 2005

• #12

Uncle Meat said:

Well explain to me why Ford doesn't install 4:10's at the factory if they are so great for gas mileage? It would raise their overall C.A.F.E. ratings which would be better for the company overall.

U.M.

Click to expand...

Because it causes the rpm to dwindle out faster. At least that's what I would assume as opposed to have a more conservitive gear. How many people like that fact that with steep gearing you your rpms are hitting 3,000 at a lower mph.

I don't know they have there reasons. Has it ever been tested or proven. Agian I don't know and I'm curious which is why I asked myth or not.

yes I know i'm weird

everyone have a great labor day weekend.

 

YardSpecial

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Mar 20, 2003

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MT

Sep 3, 2005

#13

• Sep 3, 2005

• #13

FACT:

Gas mileage will go down on the freeway.

City MPG will go up a little.

I agree with UM on this one, Ford knows what the right ratio is for MPG and 4.10 are not it.

The only reason a Vett is getting great MPG is the 6th gear and only 1600 rpm cruise rpm at 60.

THINK ABOUT IT !!!

 

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tama

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Dec 27, 2003

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San Jose, CA

Sep 4, 2005

#14

• Sep 4, 2005

• #14

Cavallo said:

FACT:

Gas mileage will go down on the freeway.

City MPG will go up a little.

I agree with UM on this one, Ford knows what the right ratio is for MPG and 4.10 are not it.

The only reason a Vett is getting great MPG is the 6th gear and only 1600 rpm cruise rpm at 60.

THINK ABOUT IT !!!

Click to expand...

Makes sense.

actually if you drive the legal speed limit you shouldn't notice a difference in gas consumption, but then again how many of us drive the legal speed limit