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What gears for 38"s??

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by 84silverK5, Dec 3, 2001.

  1. 84silverK5

    84silverK5 Registered Member

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    What gears for 38\"s??

    i need to get some gears im runnin 3.73 which is pretty worthless i know. What would be best ratio to get for wheeling, but still be able to drive on the highway without rappin out, i heard they dont make 4.88's for 14bff,
     
  2. big75jimmy

    big75jimmy Registered Member

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    Re: What gears for 38\"s??

    I would go for 4:56's. A buddy of mine ran these in his Ford with 38" Swampers. Yes, you can get 4:88's and even 5:14's for a 14 bolt. 4wheelparts wholesalers have them. If you have 4:10's or higher you will need the "thick" gears.
     
  3. 84silverK5

    84silverK5 Registered Member

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    Re: What gears for 38\"s??

    Thick? what you mean? so my 3.73's should be thick?
     
  4. 2Dogs

    2Dogs 1/2 ton status Premium Member

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    Re: What gears for 38\"s??

    4.56s if you have a strong engine. 4.88s if it is tired and you need to keep it......

    Dave

    Horn Broken... Watch For Finger.
    <a target="_blank" href=http://coloradok5.com/gallery/Daves-Pics>http://coloradok5.com/gallery/Daves-Pics</a>
     
  5. HarryH3

    HarryH3 1 ton status Author

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    Re: What gears for 38\"s??

    As the gear ratio gets lower, the pinion gear diameter gets smaller. One way to make up the difference is to use a different case, that moves the ring gear over a bit closer to the pinion gear. Another way is to use a gear set that has a thicker ring gear.

    <font color=black>HarryH3 - '75 K5</font color=black>
    <a target="_blank" href=http://www.angelfire.com/super/ThunderTruck>www.angelfire.com/super/ThunderTruck</a>
    It's a great day to be alive...
     
  6. 84silverK5

    84silverK5 Registered Member

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    Re: What gears for 38\"s??

    Ahh ok, thx ya'll
     
  7. CarolinaBogger

    CarolinaBogger Registered Member

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    Re: What gears for 38\"s??

    I just got done regearing with 4.88's for my 38's. I thought 4.88's would be way to low (high, numerically) but one of my friends does work for the Great Clips Busch series car and he said that for every true inch of tire you go up, it drips your RPM by about 250. And every step up in gear brings RPM up around 250 (give or take some). So we worked the math out and we decided on 4.88's b/c it brought the RPM's down into the torque curve where it would work best. I love the way it accelerates. I mean, my motor has 148K on it, and with these gears and 38's, it doesn't show it. However, i haven't had it on the highway so i don't know about high-speed gas mileage.

    <font color=green>"I'm old enough to know better, but I'm still to young to care!"</font color=green>
     
  8. Greg72

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

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    Re: What gears for 38\"s??

    84Silver,

    There's a thing called a "carrier-break" that occurs when you move up in the gear sizes....it's like Harry said. The pinion is getting smaller, so the ring gear has to get thicker to compensate.....However at some point, the carrier needs to be changed to allow for the really DEEP gears. On a 14BFF....the carrier break happens after 4.10s I believe....so if you are keeping the 14BFF you already have, you'll need a new carrier for anything over 4.10 anyway.

    I am running 35's with my 3.73's......no overdrive.

    I want to swap in an O.D. tranny (700R4) which will allow me to run 38's like you....with 5.13 gears (that's as DEEP as you can get on a 14BFF)....It would have LOADS of Ooomph off the line, but the coolest part.....it will actually turn LESS RPM's on the highway than my current setup!!! [​IMG]

    The overdrive tranny is a big part of why that works out so cool...if you don't have an O.D. (and don't want one) then you'll need to stick to a more traditional gearset.....4.10 would give you similar highway RPM to what you have now....if you wanted to get more aggressive....4.56s.......



    -Greg72

    '72 K5 Blazer - 427BB/TH350/NP205/6" Lift/35x12.50's
    <font color=blue>See it here: </font color=blue><a target="_blank" href=http://coloradok5.com/gallery/albun38>http://coloradok5.com/gallery/albun38</a>
     
  9. wayne

    wayne 3/4 ton status

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    Re: What gears for 38\"s??

    I have 4:56's now with 35's and plan to keep them when I go to 38's since I won't have the overdrive anymore.

    See <a target="_blank" href=http://coloradok5.com/gallery/Waynes-Toy>Project Mighty Mouse</a> here.
    <font color=blue>Wayne<font color=blue>
    <font color=blue>Happy Trails<font color=blue>
     
  10. CaptCrunch

    CaptCrunch 1/2 ton status

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    Re: What gears for 38\"s??

    4.56's or 4.88's like everyone has said. Keep in mind w/ the 700R4 you have a steeper first gear too. I think either one would work out nice... I want to go 4.88's w/ 38's and a 700 some day

    -Mikey
    1987 Chevy K5 Blazer- 350 TBI
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  11. riz

    riz 3/4 ton status

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    Re: What gears for 38\"s??

    <font color=purple> 4:88's should do you proud !

    L8r,
    . Riz . <a target="_blank" href=http://www.geocities.com/rizmonkey>www.geocities.com/rizmonkey</a>

    <font color=purple> BOW CHICKA BOW WOW !
     
  12. sapper

    sapper 1/2 ton status GMOTM Winner

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    Re: What gears for 38\"s??

    i called Randy R&amp;P a week ago pricing the same thing. my 14ff has 4:10s and to go to 4:88s you can either change the carrier or go with the Yukon gears i believe he said. They do not require the bigger carrier and they say the strengh does not drop to much. just another option.

    <a target="_blank" href=http://coloradoK5.com/gallery/Pauls89K5>http://coloradoK5.com/gallery/Pauls89K5</a>
     
  13. 1990K5

    1990K5 1/2 ton status

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    Re: What gears for 38\"s??

    my truck has a 700r4, 4:56's and 35's (34in actual dia.) it could not be moer dialed in gearing wise, its perfect. to maintain the same gearing with the 38's im putting on i will need to go 5:13's, it make the choice simple to me.
     

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