3.73 vs. 4.10 - My actual experience

Discussion in '1996 - 2004 SN95 Mustang -General/Talk-' started by merc123, Oct 4, 2010.


  1. merc123

    merc123 Active Member

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    This is a completely unbiased opinion. The reason I say this is because after I killed my other rear end with 3.73s I did a rear end swap (entire rear end). I was supposed to get 3.73 gears from FRPP and apparently they installed 4.10s. Everything on the box said 3.73's including the shipping documentation. I didn't find out until after 2 months of driving the car (which would be today) that it actually has 4.10s. It's like thinking you are about to drink water and it turns out to be a Sprite and all you taste is the soda.

    Here are the thoughts and questions I kept asking myself because it didn't seem "normal" compared to my old 3.73's I had. So if you want to know the differences...here ya go.

    1. Why am I getting out of 1st gear so quick? These 4.10's rev a lot quicker.

    2. I think I'll shift at 2k to save gas. Why am I doing 40 MPH and in 5th gear already? I have to shift at 3k to keep the momentum up with "traffic" and hit 5th pretty quick.

    3. Why is my gas mileage so bad? I went from 23-24 MPG on the highway to 20-21 MPG highway. 18 when you mix in traffic.

    4. Why is my RPM so high in 5th at 70 MPH? With 3.73's I was about 2200 or so and with these 4.10's I'm at 2500.

    5. I'm so glad I got rid of those 3.27 gears I had. I can pass cars so much easier in 5th gear without downshifting. Fact is you can pass cars without downshifting with 3.73's too....it's just easier with 4.10's since you're almost to 3k on the highway!

    6. Why are my tires spinning? They never used to spin like this before.

    Those are all I can remember for now. One issue I did take note on after figuring out I had 4.10's was my SpeedCal. I have it set for 3.73 gears, not 4.10s and my speedo is only 2 MPH less than my GPS.
    #1
  2. N8Dogg98

    N8Dogg98 Mustang Master

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    So what gets your vote... 3.73's or 4.10's?
    #2
  3. slayerripkdc

    slayerripkdc Active Member

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    4.56's for the win!!!! lol
    #3
  4. Justa2V

    Justa2V New Member

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    I dunno, I've had 4:10s for a while now and I'm glad I switched from 3:73s. I didn't notice a big difference in gas mileage really but maybe it's a bit different for automatics.
    #4
  5. streethorse

    streethorse Active Member

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    When you dont drive much per day average your not going to notice much
    difference in mpg between 3.27, 3.73, or 4.10..... or care.
    When you drive 50 + miles per day ... you care.
    Thats why I love the factory 3.27's , 2000 rpm's at 70 mph.
    4.10's would be 2500 rpm,s at 70mph ... a 25% increase in gas consumption.
    Do the math.:flag:
    #5
  6. Dark04GT

    Dark04GT Member

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    I agree, the stock 3.27's are perfect- too much hwy driving for me too. I like my gas mileage in the mid-upper 20's.

    I know the 4.10's are great for the 1/4 mile but I DD my stang and don't need the gear. I don't care how many people say their gas mileage is the same, the simple fact is that is impossible to keep the same gas mileage- you do lose gas mileage (however small, it would add up for me).
    #6
  7. Tim2002GT

    Tim2002GT Founding Member

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    5 speeds + 4.10's ftw! I'm only turning 2300 @ 70 mph.
    #7
  8. merc123

    merc123 Active Member

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    I have a 5 speed.... It's turning 2500 @ 70.

    I originally bought the 3.73's because I have a 100 mile commute, one way and the Stang is the my current DD. I don't really care for the 4.10's for this commute.

    If you don't have a long commute to work and just drive the Stang for fun then get the 4.10's. Otherwise go with 3.27 or 3.73s.

    Acceleration wise I feel no difference between the two gear sets.
    #8
  9. Tim2002GT

    Tim2002GT Founding Member

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    Idk man, my gps is right on with my speedo. @ 2500 rpm I am doing just under 75 mph.


    edit: The tranny in my car is from an 04 Mach 1 with the 0.62 5th gear ratio. The GT 3650 5th gear is 0.67 I believe. That is why mine is turning less rpm @ 70 mph than yours.
    #9
  10. 04DarkShadowGT

    04DarkShadowGT Member

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    I'm not sure you can do a direct correlation to say that 500rpm more is 25% less gas consumption. I don't imagine you would go from 25mpg highway to 18.75mpg highway by going to 4.10 gears.

    Hell I can pull 18-19mpg highway with my blown gt, with an auto, 4.10s, 3500 stall.
    #10
  11. twogts4us

    twogts4us Advanced Member

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    The difference between 3.73 and 4.10 is huge. My wife's 01 had 4.10s and I thought they were a bit much so I went with 3.73s for my 02 - BIG MISTAKE.
    #11
  12. streethorse

    streethorse Active Member

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    25% is probably a bit exaggerated on my part. :D While rpms does affect
    mpg somewhat, how hard you accelerate probably plays a bigger part.
    But anyway the 3.27 gears are really a benifit for highway driving.
    #12
  13. 98COBRA281

    98COBRA281 Active Member

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    now were talking!! i love my 4.56's!
    #13
  14. BiminiBlueLX

    BiminiBlueLX New Member

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    I know you're on the subject of 4.6s, but 5.0s can run high 11s with 3.73s. :nice:

    See for yourself
    #14
  15. Tim2002GT

    Tim2002GT Founding Member

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    Throttle position plays a big role as well. With 4.10's you don't need as much peddle as you would with 3.73's to accelerate at the same rate. Driving style plays the biggest part of getting good mileage.
    #15
  16. Tim2002GT

    Tim2002GT Founding Member

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    True, but typically the 5.0's make a little more low-rpm torque so they don't need as much gearing as a 4.6.
    #16
  17. merc123

    merc123 Active Member

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    Very true Tim. I'm still getting used to the throttle and clutch. I'm really jerky on starts at occasion because I can just about slip the clutch without any gas at all.
    #17
  18. Nightfire

    Nightfire Mustang Master

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    WTF? 4.6's can run high 11's with 3.73's too, even with stock 3.27's. Thanks for the pointless post :nice:
    #18
  19. mazen189

    mazen189 Member

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    I Love my 3.73's. Its a great combination for street, highway use, my daily commute and confortability. If i wanna spin my tires outta third, i have a nozzle I can easily open. On the other hand, I believe the 4v's love the 4.10's more than the 2v's. I might be a bit bias, but, as you stated first, I dont wanna be in 5th gear going 40mph.
    #19
  20. 03_TrueBlue_GT

    03_TrueBlue_GT Active Member

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    I love my 3.73's as well but I think it depends a lot on how far you drive every day, I usually drive 45 miles a day to and back from school/work and mostly city driving. Funny things is the 3.73s actually increased my mileage from 17.5 to 19.5mpg with mixed city and highway driving and thats shifting around 2400rpms to hear the flows:D, and yes I love how the rearend gets loose now when you punch it in a corner..:rolleyes:
    #20

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