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203, what are my options besides MileMarker?

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by Steve_87K5, Nov 4, 2003.

  1. Steve_87K5

    Steve_87K5 1/2 ton status

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    I want to keep the original (lo-lok, lo, N, hi, hi-lok) operation. But I want to NOT engage the front axle all the time when on-road. Is there a way to do this? MileMarker locks the 203diff 100% of the time as I understand it.
     
  2. ankarback

    ankarback 1/2 ton status

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    What I know of, it´s no other way to do it but locking the 203diff. With the milemarker kit you can disconect the frontaxel and the driveshaft if you have freewheelinghubs in the frontaxel.
     
  3. HarryH3

    HarryH3 1 ton status Author

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    In the non-locked positions a 203 sends power to both driveshafts, through a differential. Unlocking the front hubs means that the rig won't move, as all the power will be transferred to the front driveshaft. It's just like when one tire of an open differential 2WD is sitting on ice. Even though the other tire can be on dry pavement, the vehicle won't move as all the power is being dumped to the tire that's spinning on the ice. When you shift a 203 to a locked position the differential gets locked, just as if you had an ARB locker in in. /forums/images/graemlins/cool.gif However, the 203 was never designed to have a 2WD output. It always sends power through that diff inside unless you covert it to a part-time case.

    There are some transfer cases on newer rigs that allow part time and full time operation, but they were designed that way from the ground up. /forums/images/graemlins/cool.gif
     
  4. Goober

    Goober 1/2 ton status

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    The NP203 transfer case has a differential inside that divides power between the front and rear axles. It is exactly the same (operationaly) as an open differential in your axles except that you have the option to 'loc' the case to send power to both axles even if both wheels are spinning on the front or rear.

    Installing the Milemarker kit (either the lugs or the shaft replacement) eliminates the differential in the NP203. When installed, you get 4WDlo-lok, 2WDlo, N, 2WDhi, 4WDhi-lok. Of course you also get the manual hubs that need to be engaged in order to have 4WD. Being able to disengage the front axle momentarily is a lifesaver if you have a locker in the front.


    With the Milemarker kit you generally drive around all day with it in 2WD Hi. When you leave the pavement, just lock you hubs and shift between 4WD and 2WD whenever you want.


    I've installed quite a few of both types of kits from Milemarker and really like them. They are an inexpensive way to get some added functionality for your NP203.


    BTW: You will hear alot of folks telling you that you will get much better gas mileage since you won't be turning your front axle all the time. I wouldn't count on it. The real benefit is the functionality and reduced wear on the front axle.



    Does that help?
     
  5. Steve_87K5

    Steve_87K5 1/2 ton status

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    Thanks for the info guys. Another way I coulda asked the
    question: does any company make a mini "ARB" for the 203 differential? Some Land Rovers have this feaure. It's a small knob you pull up on to lock the transfer case diff.
     
  6. HarryH3

    HarryH3 1 ton status Author

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    The 203 already has a selectable "locker" inside. It just doesn't give you a 2WD option unless you also lose the full-time 4WD option. /forums/images/graemlins/frown.gif
     
  7. imiceman44

    imiceman44 1 ton status

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    [ QUOTE ]
    Thanks for the info guys. Another way I coulda asked the
    question: does any company make a mini "ARB" for the 203 differential? Some Land Rovers have this feaure. It's a small knob you pull up on to lock the transfer case diff.

    [/ QUOTE ]

    You got all the answers here except, you mentioned the Range Rover and Land rover, you DO know they are also full time 4wd?
    I don't know about the newer late 90's and up but the earlier ones all had full time 4x4, and the loc was vacuum operated instead of hard lever like the 203 is.
    My friends actually converted their vacuum system to linkage because they had problems with it and they copied my 203 system to do so.
    Just some useless info /forums/images/graemlins/grin.gif
     
  8. Steve_87K5

    Steve_87K5 1/2 ton status

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    Iceman...yes, his Rover vacuum thing worked about half the time. Solid linkage the way to go.

    One more 203 (hypothetical) question:

    Say, there was another shifter that only did engage/disengage of the front axle, (my M37 had this).
    And I added locking hubs to my front axle.
    Then, for ON road highway driving :
    -set hubs to OPEN
    -set front axle to OFF (hypothetical feature)
    -set 203 to HI-LOK

    Would this work for ONroad? I'm thinking this would preserve the full-time 4WD capability of the 203, and also
    have the option of NOT running the front driveline when I didn't want to.
     

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