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38's and what gears???

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by blazen_md, Oct 27, 2002.

  1. blazen_md

    blazen_md 1/2 ton status

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    38\'s and what gears???

    I recently purchased a 77 1 ton 4x4 60 in the front 14ff in the rear. It has 4.10's in it now. I am swapping these axles to my 90 k5. I will be running 38's with 6 sus. and 3 bod. I have a 350tbi in the truck with 700r4. People are telling me to keep the 4.10's and when my 700r4 goes put a th350 and 205 case in and my setup should be just right with the 4.10's. What I am wondering is if this sounds good enough or if I should go with 4.56's or if anyone runs this combo. I will also be running a detroit in the back and a powerloc in the front. Any help would be appreciated. Thanks.
     
  2. thatK30guy

    thatK30guy 1 ton status Premium Member

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    Re: 38\'s and what gears???

    If you do a lot of freeway driving, leave the 4.10's in it.

    But if you want some power and drive more in town, get the 4.56's as the overdrive will compensate for the freeway RPM's.
     
  3. mudhog

    mudhog THEGAME Staff Member Super Moderator

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    Re: 38\'s and what gears???

    with the overdrive get 4:88's i have the sm465np205 combo with 4:10's and 38's and i wish i had at least 4:56's
     
  4. Shaggy

    Shaggy 3/4 ton status

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    Re: 38\'s and what gears???

    <font color="green"> I think you should go with 4.56s right away. I ran 4.10s with 38s and a SM465, and the gears were not really bad, but 70mph in 4th gear I was only turning like 2400rpm. You could go to 4.56s and still be able to get to highways speeds very easily. </font color>
     
  5. HarryH3

    HarryH3 1 ton status Author

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    Re: 38\'s and what gears???

    With 4.10's you wont' hardly ever be able to use overdrive. /forums/images/graemlins/frown.gif The engine would only be turning 1,500 RPM at 60 MPH. In direct drive it would be turning 2,150 RPM.

    4.56's would only bring it up to 1,670 RPM in overdrive and 2,390 RPM in direct drive.
    4.88's would bring it to 1,790 RPM in overdrive and 2,550 RPM in direct drive.
    5.13's would bring it to 1,880 RPM in overdrive and 2,690 RPM in direct drive.

    If you think you'll keep the 700R4, then I'd go with 5.13's to have a really driveable truck. /forums/images/graemlins/shocked.gif If you think you'll go to a Turbo 400 at some point, then just install the axles with the 4.10's in them and drive with the 700R4 in drive instead of overdrive to get an idea of what it would be like with the 400. Keep in mind that the 400 doesn't have a lockup converter, so the engine will turn a couple hundred RPM higher due to converter slippage in the 400. The 400 also has a much higher first gear, so it will make the truck slower off the line, but at highway speeds the 700R4 in drive will be fairly close to what the Turbo 400 will be like. /forums/images/graemlins/cool.gif
     
  6. thatK30guy

    thatK30guy 1 ton status Premium Member

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    Re: 38\'s and what gears???

    Damn you! Now you got me thinking about the 4L80E now!! /forums/images/graemlins/rotfl.gif /forums/images/graemlins/thumb.gif
     
  7. HarryH3

    HarryH3 1 ton status Author

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    Re: 38\'s and what gears???

    It's only money Wes, it's only money... /forums/images/graemlins/wink.gif
     
  8. tRustyK5

    tRustyK5 Big meanie Staff Member Super Moderator GMOTM Winner Author

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    Re: 38\'s and what gears???

    Maybe he could sell his goat? /forums/images/graemlins/eek.gif /forums/images/graemlins/grin.gif

    Rene
     
  9. thatK30guy

    thatK30guy 1 ton status Premium Member

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    Re: 38\'s and what gears???

    Ok, I think I'm ready to sell you my goat.....the one you've been bugging me about! /forums/images/graemlins/shocked.gif /forums/images/graemlins/thumb.gif /forums/images/graemlins/rotfl.gif
     
  10. thatK30guy

    thatK30guy 1 ton status Premium Member

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    Re: 38\'s and what gears???

    If only we had your money, Harry....... /forums/images/graemlins/wink.gif /forums/images/graemlins/thumb.gif
     
  11. tRustyK5

    tRustyK5 Big meanie Staff Member Super Moderator GMOTM Winner Author

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    Re: 38\'s and what gears???

    What...and give up my sheep? /forums/images/graemlins/rotfl.gif /forums/images/graemlins/rotfl.gif

    Rene
     
  12. HarryH3

    HarryH3 1 ton status Author

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    Re: 38\'s and what gears???

    Sorry! I gotta keep mine for me (well, it seems that the wife and kids use up most of it!!. /forums/images/graemlins/wink.gif
     
  13. thatK30guy

    thatK30guy 1 ton status Premium Member

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    Re: 38\'s and what gears???

    Oh, you have some sheep? /forums/images/graemlins/eek.gif You can keep them! /forums/images/graemlins/thumb.gif
     
  14. thatK30guy

    thatK30guy 1 ton status Premium Member

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    Re: 38\'s and what gears???

    Then adopt me, Harry! /forums/images/graemlins/deal.gif /forums/images/graemlins/thumb.gif
     
  15. Tweetysuarus

    Tweetysuarus 1/2 ton status

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    Re: 38\'s and what gears???

    I am runnin 4:56 detroit lockers Fr &amp; Rr w 38.5's, I am plannin on upgrading my gear set to 5:13's! right now I can cruise the freeway at 75mph so I figure with 5:13's I should be able to pull at least 60mph easy and have more power on the trails! JMO!
    Bill
     

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