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np203 4WD QUESTION

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by hungryjpr, Mar 15, 2002.

  1. hungryjpr

    hungryjpr Registered Member

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    How does the t-case lock the front output when in 4lo? Also, does this ever wear/break?
    My problem is that I cannot get the front output/d-shaft locked. If I pull the rear d-shaft, no forward movement. I suspect that the locking mechanism is worn or broken. Is this common?
    I have eliminated the possibility of maladjusted linkage by disco'ng all the shifters - I am shifting straight outta the case.
    Matt B
     
  2. 1bigk10

    1bigk10 1/2 ton status

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    The np 203 uses a differential in the center of the case to transmitt power o both outputs as they need it.
    I suggest a part time kit. or swap to an np205.
     
  3. Leadfoot

    Leadfoot 1/2 ton status Premium Member

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    203 t-case are known for having the shifting linkage needing adjustment from time to time and especially after body lifts. I would check your adjustment first. Do a search the technique to adjust was just explained recently. I have also seen it on the web if you search too. Hope this helps
     
  4. hungryjpr

    hungryjpr Registered Member

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    Correct me if I am wrong here, but I was under the impression that the the t-case differential locks in 4lo. If not, then I understand what the problem is.
    I'm planning on using the 203 in a doubler install, but just want to do some test wheeling to work out a few other bugs before that phase of the build-up.
    Matt B
     
  5. Leadfoot

    Leadfoot 1/2 ton status Premium Member

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    It does lock in lo loc and hi loc. It could be misadjustment or the locking mechanism could have broken. I can't really help on the internals I have not taken one apart, maybe somebody else could shed some light.
     
  6. Big_B_Murphy

    Big_B_Murphy 1/2 ton status

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    When you say 4 lo do you mean low lock as with a 203 you have low (all the way forward), low lock(one notch back), neutral, high and high lock.
    Does it lock in hi lock? (all the way back).
     
  7. weisel

    weisel 1/2 ton status

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    I have had three of these cases apart and know what you are talking about. First, you said that you took the shifter off, and am shifting by those little levers on the side of the case...right? well, one of them controls the high/neutral/low selection. You can tell which one it is because it has three positions. The other one only has two positions and coltrols the locking of the differental inside of the case. This is the one that you should be moving into loc.
    Yes, the two gears that lock together do wear out (thats whats happened to two of mine), and that would cause no forward movement. No one I can find still makes these parts, but you might be able to find some used and rebuild the case, although my sugestion is to just get a used 203.
     
  8. TrcksR4ME

    TrcksR4ME 1/2 ton status

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    I know on mine, which has a part time kit, that it must lock or something in 4 wheel, because I have done some front wheel driving when I lost a u-joint on the rear shaft going down the road. And that was in 4 high. If you are gonna do a doubler, at least you have the satisfaction of being able to chuck that chain and differential from your 203 /forums/images/icons/smile.gif
     

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