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from 3.42 to 4.10 in a 12 bolt

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by Blazinaire, Sep 16, 2002.

  1. Blazinaire

    Blazinaire 1/2 ton status

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    Is the carrier change to a 4 series at 3.42 or 3.73? Just need to know if Ducttape will need to buy the regular or thick gears. Also, what are your thoughts on running 37''s with 4.10 gears 6.2 diesel and th350? Will that be enough gear or should he go with 4.56's, remember low RPM's from the diesel and no OD.
     
  2. heavy4x4

    heavy4x4 1/2 ton status

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    Not positive about the "4 series" change thingy, but what I recall is that a carrier change isn't needed unless the ratio from the factory was numerically lower than 2.73. Hope I'm talking about the same thing you are, but maybe I'm way off. As far as the rpm's, I calculated that with that setup, (4.10's) he'll be turning 2420 rpm at 65 mph. Sounds a little high for a diesel to cruise comfortably. I definitely wouldn't go with 4.56's.
     
  3. mudhog

    mudhog THEGAME Staff Member Super Moderator

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    honestly i wouldnt go with 37's and a 12bolt i shaterd my 12bolt in the sand with 3:73's and 33's /forums/images/icons/shocked.gif
     
  4. monypit

    monypit Registered Member

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    Those pics are pretty cool but don't you think the shattered 12bolt has more to do with the air factor than the tire size. Cool jump though.
     
  5. mudhog

    mudhog THEGAME Staff Member Super Moderator

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    actually it broke a year later climbing one of the bowls at sand lake /forums/images/icons/shocked.gif
     
  6. zakk

    zakk 1/2 ton status

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    i personally would look for a 14B with 4.10's. you can usually get a 14B for $250 or so, and 4.10's are pretty common.

    this would be heavy duty, easily swap-able, and already have the gears installed, which is usually pricey unless you can do it yourself (which i cannot)

    Also, gears are an extra $120 or so at the cheapest place on earth.

    So for less than it would cost you to swap gears, you can have the 14B with correct gears.

    JMHO.
     
  7. RESTORE89

    RESTORE89 1/2 ton status

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    i agree look for a 14b
    i use 4.10 with 33's in my 10 bolts but i have od. seem like you should be about right with the diesel and no od with 37's may not quite have as much low end as you mioght want, but maybe the diesel will make up for that. not much experience with smokers.
     
  8. Blazinaire

    Blazinaire 1/2 ton status

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    The reason we are using a 12 bolt is almost entirely because of the "snag" factor of the 14 bolt. At Blazer Bash we saw countless people get hung up and high centered because of the low hanging (even after they were shaved) 14 bolts and trucks with 10 bolts could get through with relative ease. Also we will eventually be installing an ARB and there aren't (as of now) any selectable lockers for the 14 bolt. We already have the 12 bolt housing, new brakes, and several spare axleshafts. Gears and install kit are under $200 from gears 4 less and we do posses the skills to install them properly. Also, did any of you see the 73-75 blazer at BB on 44'' swampers with 4.10 gears a single 203 (?) and D44/12 bolt? He ran rusty nail with no breakage. For the amount of hardcore rocks around here we can get away with 37''s without much trouble. So back to the original question, are 4.10's a good choice and will we need the thick gears to use them on the 3.42 carrier?
     
  9. RESTORE89

    RESTORE89 1/2 ton status

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    regular gears should work since they are that close in number the thick gears are for like 273 or lower i think
    i bought mine from randys ring and pinion and pain like 135 for 410 but that was for 10 bolts
     
  10. Blazinaire

    Blazinaire 1/2 ton status

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    sounds good to me, thanks /forums/images/icons/cool.gif
     

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