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Difference between 4.10 and 4.56 gears

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by blzr4x4ngkid2, Oct 28, 2003.

  1. blzr4x4ngkid2

    blzr4x4ngkid2 Registered Member

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    I might need to rebuild the rear end. I wasn't sure about the gear ratio to put in it. I have a TH350 and I was thinking 4.56s to run 40" Boggers, the tires on the truck now. Am I going to notice a difference with 4.56s or should I go higher? I still want to drive on the highway to work, but I also want it to get up and move. I drive the hog on a daily basis. In other words, ALL THE DAMN TIME!!
     
  2. Zeus33rd

    Zeus33rd Smarter than you GMOTM Winner

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    Hmm...

    With 40's and the auto tranny, I'd think 4.88's or 5.13's. I think you'd be most happy with the 5.13's. If Zakk sees this thread, perhaps he'll comment. He's running the 5.13's & auto tranny. Do you drive it on the street much?
     
  3. shane74

    shane74 1/2 ton status

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    I am switching to 5:13's to run my 38's. According to Interco's tire calculator, 5:13's with 37" to 40" tires puts your rpms and gear ratio close to the stock gear/tire size ratio. Right now, I am running 3:73's. I hope to see a BIG difference in the way it drives. I know I'll have higher rpm's on the freeway, but as it is, I can't pull a slight hill and maintain speed w/out having to smash the skinny peddal. /forums/images/graemlins/tongue.gif A long steep grade is a whole 'nuther world of hurt! /forums/images/graemlins/tongue.gif
     
  4. Greg72

    Greg72 "Might As Well..." Staff Member Super Moderator

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    Going from 4.10 to 4.56 would seem like a meaningless change....

    You have to buy a new carrier for anything 4.56 and up, so it's going to cost more than just a gearset. I'm running 38's and 4.10s and even with a BBC, it's a dog.

    4.88 would be my suggestion if you HAVE to still drive it a lot....

    5.13 if you want it to MOVE...and are willing to spin a few extra RPM on the highway.
     
  5. jekbrown

    jekbrown I am CK5 Premium Member GMOTM Winner Author

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    i want 5.13s for my 350/700/205 setup, even with 35s. /forums/images/graemlins/grin.gif hardly ever get into OD as it is, and 5.13s would help when the 39.5s are on the beast. /forums/images/graemlins/thumb.gif

    j
     
  6. madmike

    madmike 1/2 ton status

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    I'm running a 489bbc, SM465, 4:10 gears, and 38's. My engine makes plenty of torque and power, but it is still not quick on the street. Off road, there seems to be plenty of power/gearing, but if I had to change gear ratios, or put a larger tire on, I'd definitely go at least 4:88's.
     
  7. rampage

    rampage 1/2 ton status

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    You don't need to change the carrier for 4.56, you can get thick gears. He would need a new carrier for 4.88 and up. /forums/images/graemlins/thumb.gif
     
  8. 84_Chevy_K10

    84_Chevy_K10 Banned

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    [ QUOTE ]
    You don't need to change the carrier for 4.56, you can get thick gears. He would need a new carrier for 4.88 and up. /forums/images/graemlins/thumb.gif

    [/ QUOTE ]

    Actually even 5.13 comes in thick gears.

    The '60 front would require a new carrier though if he has one.

    My truck has 4.10s and 38s and I don't think it's that bad. I had 35s on it before and it still pulls itself about the same. I think the 4 speed really makes up for it though.
     
  9. shane74

    shane74 1/2 ton status

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    [ QUOTE ]
    5.13 if you want it to MOVE...and are willing to spin a few extra RPM on the highway.


    [/ QUOTE ]

    Yup..exactly. /forums/images/graemlins/thumb.gif
     
  10. Silverado_K5

    Silverado_K5 1/2 ton status

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    I had 5.13's in a 68 SWB 4x4 with a 305/350trans/205TC and 38" Gumbo radials. It ran 58 mph down the highway at 3000 rpm. Just some data FYI.

    Doug
     

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