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gearing for my suburban... got some ???s

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by muddysub, May 6, 2002.

  1. muddysub

    muddysub 1 ton suburban status Staff Member Moderator GMOTM Winner

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    okay, my suburban is my daily driver so i want some mileage, i get about 8-9/forums/images/icons/tongue.gif in town now and i'm afraid that with 4.56s that'd go WAY down to like 5-6./forums/images/icons/mad.gif so i'm knida thinking about 4.33s. BUT... i have 36" TSLs now and plan on going to 38" TSLs next and then like 42"s, so 36"s are the smallest tire i'll ever run (hopefully). that means i would want to go with like 4.56 or 4.88s but it's still a daily driver. so what do i do?

    does anyone in here run 4.56s and 36" TSLs on their daily driver? what kinda mpg do you get?

    <FORM METHOD=POST ACTION="http://coloradok5.com/forums/dopoll.php"><INPUT TYPE=HIDDEN NAME="pollname" VALUE="1020750938muddysub">


    gearing for the sub
    <INPUT TYPE=RADIO NAME=option VALUE="1">go with 4.56s
    <INPUT TYPE=RADIO NAME=option VALUE="2">go with 4.33s
    <INPUT TYPE=Submit NAME=Submit VALUE="Submit vote" class="buttons"></form>
     
  2. Hossbaby50

    Hossbaby50 3/4 ton status

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    I think you need 4.56's /forums/images/icons/wink.gif No but seriously, DesertDueler ran 4.56's on his Jimmy with 35's. He got decent mileage ( i think around 10mpg or better) but his Jimmy was missing hardtop and other stuff so it was lighter then your Burb by a few pounds. Also his truck was freakish, and got like 15 mpg on the highway with a carb. The best I ever got was 13 on the highway with 3.73's &amp; 32's.

    Count your lucky stars, I am going to be running 4.56's &amp; 32's for awhile after my axle swap is complete this summer./forums/images/icons/frown.gif
     
  3. gokartergo

    gokartergo 3/4 ton status Staff Member Moderator

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    With 4.56's your gas milage goes up around town..Your not smashing on the skinny pedal as hard to get up to speed.Mine went up around town..But got worse on the freeway....Dan
     
  4. Blazinaire

    Blazinaire 1/2 ton status

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    I'm pretty sure that nobody makes a set of 4.33 gears do they? I have 4.56's with 35''s and they work great, I get 11mpg and that is the same as I got when I had 3.42's with 32''s. What are your gears right now? Sometime when you go to lower gears you will get better mileage because your motor doesn't have to work as hard.
     
  5. MudbogAD

    MudbogAD 1/2 ton status

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    Scott, I told you you should run 4.56's. The Jimmy has 4.56's with smaller tires than yours and it gets around 9 in town. If you go to 4.33's you won't be better off. You might even get better mileage around town with 4.56's. Anyway, what would you rather have in your heavy ol' 3/4 ton suburban with 36" TSL's? I think 4.56's dude./forums/images/icons/wink.gif
     
  6. funkycold

    funkycold 1/2 ton status

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    I have an '89 1/2 ton with 36's and am running 4.56 gears. I drive to and from work everyday and get about 400 miles on 36 gallons.
    Go with the 4.56 it will work best for you.
     
  7. DesertDueler

    DesertDueler 1/2 ton status

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    I get 15 mpg on the freeway or in the city. It doesnt matter. I dont know why, but my truck has always go tthe same gas milage. Even when it was all stock with 3.73s and 31s. I am sure the 700r4 helped out on the freeway. But 4.56 gears put you at about the same rpm range as the 3.73 and 31 combo, so go 4.56

    Dan
     
  8. if you're going to go bigger than 38s i'd go for 4.88s. don't want to have to do two gear swaps. mileage? who dives FS chevs for their mileage?! /forums/images/icons/smile.gif
     
  9. 84_Chevy_K10

    84_Chevy_K10 Banned

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    What do you have now? 3.73s or 4.10s, I'd think. If you have 4.10s I'd leave them, 2500 or so RPM on the highway is plenty to pull it down the road.

    If you're going to change, go to 4.56 or you'll regret it.

    That said, I've got to run 4.10s and 31s on my C30 without overdrive. It's ROUGH!! 3000 RPM @ 65 sucks.

    But....It gets 13 mpg on the highway. It has a 350 TBI just like yours.
     
  10. dyeager535

    dyeager535 1 ton status Premium Member

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    With as tires as large as you are contemplating, I'd say that no matter what gear you put in there, city mileage will not suffer.

    Dads truck, 350 or 454, same truck (4.10 gears) averages the same in the city, freeway is where the mileage difference comes up. Still think about 2500RPM for a stock/mild 350 @60mph is what people should be shooting for.
     
  11. ChevBlazin

    ChevBlazin 1/2 ton status

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    A friend of mine just swapped in axles with 4.88's in his 87 Jimmy. He's running 35" bfg's and luckily has overdrive. He doesnt know what RPM he runs on the freeway, but says it sounds high. I think he still gets around 10 mpg
     
  12. muddysub

    muddysub 1 ton suburban status Staff Member Moderator GMOTM Winner

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    i have 3.73s now, i'm thinking about the 4.56s now that i've read all these. thanks! but keep em coming!
     
  13. JIM88K5

    JIM88K5 1/2 ton status

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    So you want to have your cake and eat it too ?
    I've got 35's &amp; 4.56's and I'm happy...
    Jim
     
  14. dysphemism

    dysphemism 1/2 ton status

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    I run 4.56s and 38s. The gearing is nice in town but has absolutely no guts on the freeway. I would say that freeway milage will drop considerably. I keep the pedal to the floor on slight inclines when on the freeway just to maintain my speed. If you can live with going 55-60 itll work for ya but 65 and over is a major strain unless you get some more ponies working for ya.
     
  15. muddysub

    muddysub 1 ton suburban status Staff Member Moderator GMOTM Winner

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    yeah, i've got an engine in my backyard ready to be rebuilt now so the ponies will come some day. mudbogad and i are rebuilding it into a 383 stroker and it will probably end up in the suburban.
     
  16. muddysub

    muddysub 1 ton suburban status Staff Member Moderator GMOTM Winner

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    thanks a lot guys! i'm going with the 4.56s now /forums/images/icons/smile.gif/forums/images/icons/wink.gif
     
  17. Mr7dblzero

    Mr7dblzero Registered Member

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    Aloha. Well next week I will be purchasing a 8" lift all springs and will be getting the 16x16.5x 38 TSL and I was wondering the same ? about what kind of gearing to get. I have a 85 K20 Suburban and was looking at getting at least 4.88 at the least. I also will be using my ride as a daily driver. I also was wodering about locker's. Limited in the front in my Dana44 and Lockers in my 14bolt rear. Dam this is a expensive hobby. but gearing and lockers are going to have to wait 4 awhile until I can save up enough green stamps. When I get pictures I'll send them your way. Aloha From Honolulu Hawaii.
     
  18. scotty1

    scotty1 1/2 ton status

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    The ratios work out for the 35" and 36" at 4:56, this should keep the engine RPMs in the good range for optimum power and mileage.
     
  19. muddysub

    muddysub 1 ton suburban status Staff Member Moderator GMOTM Winner

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    with 38"s i'd go with 4.88s. i plan on going to 38s next but i don't know what rim size. i want 15s cuz of the inner safety bead but i already have the 16.5s.
     

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