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37s with 4:10s???

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by sapper, Sep 1, 2001.

  1. sapper

    sapper 1/2 ton status GMOTM Winner

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    Well i just put in new axles (really The General did and i made the coffee) and they have 4:10s which work great with the 35s but of course now i want even bigger. With some handy trimming i figure i can put in some 37s and want to know from people running this set up how well it does or if it doesnt. The engine is a TBI 350 with 700R4 NP241 and 14ff on the back. Thanks

    <a target="_blank" href=http://coloradoK5.com/gallery/Pauls89K5>http://coloradoK5.com/gallery/Pauls89K5</a>
     
  2. DesertDueler

    DesertDueler 1/2 ton status

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    You should be fine. I have a 350, 700r4, and NP208, and I run 35s with 3.08s. I have this way for 30,000 miles. Me buddy has a 89 Jimmy with 350, 700r4, and NP241, and he runs 35s with 2.73s. He driven this way for 100,000 miles. His tranny is original, and mine was replaced the same time the 35s went on. Hope this helps

    86 Jimmy 4"lift 35"MTRs Other cars 69Firebird w/525 hp,and 70GTO live in PHX,AZ<a target="_blank" href=http://www.geocities.com/modifierperformance>My vehicles</a>
     
  3. RESTORE89

    RESTORE89 1/2 ton status

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    with those gears and tires it kinda negates the purpose of the 700 i would think.
    is it possiblr to even use th OD
    sounds like the rpm's would be way to low

    It needs a bigger motor.
    what's in it now?
    doen't matter it NEEDS A BIGGER MOTOR
    89 350tbi/700r4h/np208/4.11's
     
  4. 2Dogs

    2Dogs 1/2 ton status Premium Member

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    I agree with restore - maybe too low for OD. Check an RPM calculator.
    Strain in OD is the quickest way to ruin the 700R4. Is the truck a daily driver? If not, you should be fine. And maybe not using OD......

    Dave

    Horn Broken... Watch For Finger.
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  5. DesertDueler

    DesertDueler 1/2 ton status

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    You can use over drive on the freeway, but no in the city. Using over drive in the city is the biggest killer on trannys. I use over drive on the freeway because my truck can still do 90 mph real easy. My buddies on the other hand can only do 65 mph, so he doesnt use over drive. Just make sure you have a tranny cooler. The stock one works fine, if you have one.

    86 Jimmy 4"lift 35"MTRs Other cars 69Firebird w/525 hp,and 70GTO live in PHX,AZ<a target="_blank" href=http://www.geocities.com/modifierperformance>My vehicles</a>
     
  6. 2Dogs

    2Dogs 1/2 ton status Premium Member

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    Yes - 90 would be fine for OD. But if you try to stay in a speed limit of 55 - 65, I think that would be too much load for OD.

    Dave

    Horn Broken... Watch For Finger.
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  7. michaelm

    michaelm 1/2 ton status

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    when you load it into the calculator you should use actual MEASURED size not the 35 or 37 from the side wall. some 35s measure a lot closer to 33 and some 37s measure a lot closer to 35. the most accurate would be to measure the tire circumference, maybe by a chalk line on the tire and rolling it one revolution. if you measure the rollout it would be handy for others if you post the findings.
     
  8. tRustyK5

    tRustyK5 Big meanie Staff Member Super Moderator GMOTM Winner Author

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    Actually loaded radius is the most critical dimension needed...and that can be found by measuring to the center of the axle tube.

    Rene

    <font color=green>Dyslexics of the world...UNTIE!</font color=green>
     
  9. michaelm

    michaelm 1/2 ton status

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    circumference is what you are after. think about it. you will take your loaded radius # and put it in a formula that calculates a circumference #... which i bet is wrong.
    seeing as the tire isnt a perfect circle(the contact patch flattens to the ground but doesnt shorten the actual distance of the tread) the loaded radius thing seems incorrect.
    i think of the tire more as a track on a dozer, fixed length(measured rollout), as i doubt the steel belts that make the shape of the tire are going to expand or contract much with a few pounds air pressure.
    that is just my opinion you are welcome to your own
     
  10. CaptCrunch

    CaptCrunch 1/2 ton status

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    Well I have the current 35" MT's w/ 4.10's and a 700R4 and I'm currently at a crossroads. I think the 4.10's and 35" MT's work, but I think for a true 35", 36", or 37" swamper you are gonna need more gear. I would actually like 4.56's w/ my current setup and am debating about 4.56's or 4.88's for 36-37" swampers. I also want to be able to still tow in 3rd yeah even w/ 37's... what the heck [​IMG] So along the same question lines anyone got either combo and their thoughts on it?

    -Mikey
    1987 Chevy K5 Blazer- 350 TBI
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  11. 84_Chevy_K10

    84_Chevy_K10 Banned

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    I too have 4.10s and 35" BFG M/Ts. If I wasn't swapping to a 4 speed, I'd have at least 4.56 gears for the 35s. Since I'm planning on 37s, I was planning on 4.88 gears. Maybe that wouldn't even be enough.

    I can't imagine wanting to drive a truck with 4.10s and 37s all the time. I ache for more gear every time I get on the highway.

    Tim
    '84 Chevy K10, lifted, loud, fast, and 3/4 ton axles
     

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