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NP203 to part time

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by langsoffroad, Aug 22, 2002.

  1. langsoffroad

    langsoffroad Registered Member

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    How can i tell if the 203 i picked up used has already been converted to part time. i'd like to know before i install. chrslang@gte.net
     
  2. R72K5

    R72K5 Banned

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    id like to know sure fire way to tell also, i tried in 2 hi range and with hubs disengaged and the front d-shaft wil turn about 1/2" either direction and thats it, clunk* clunk*

    auto trans in park when doing this*


    thanks for anything, i appreciate anything at all.
     
  3. shane74

    shane74 1/2 ton status

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    Then yours is not converted. If it was, then the front drive shaft should spin like the t-case was in neutral anytime it's not locked in. I'm not sure how to tell by just looking at one though. I think you'd have to take the cover off and look for the conversion kit inside?? Not sure though.
     
  4. Grim-Reaper

    Grim-Reaper 3/4 ton status Author

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    Yeah that's the best test. Spin the front shaft. In park CHOCK THE WHEELS if you don't trust your parking brake. If that case is not converted and you have it in High or Low it could roll if the front hubs are unlocked.
    Now with tranny in park and the case in High or Low (not LOCK) the front drive shaft should be able to spin by hand. If it won't spin then the case is still full time.
    Factory these truck came With a Drive flang/ Slug. It was a solid hub installed like the inner part of a locking hub. Where the dial of a locking hub would be it just has a little chrome hub cap.
    To test one out of the truck the tse would be hold the INPUT shaft. Spin the rear output shaft. If it's part time the your going to fight yourself on the input shaft . If it's full time the front output will start spinning but you will be able to preven the input from spinning.
     
  5. R72K5

    R72K5 Banned

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    i have no clue either, dunno what parts are added or remove din a part time 203 conversion kit,

    im gonna try again at manually turning shaft with 203 in hi or lo and see..

    i dont see how truck can ever roll with the th350 in park, unless case in neutral ??

    this is too damn complicated.... lol

    thanks
     
  6. R72K5

    R72K5 Banned

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    ok front d-shaft will turn by hand in lo but not in hi

    i dont know what it will do in either loc position, havent tried


    th350 in park and hubs disengaged

    explain that ?

    thanks
     
  7. Grim-Reaper

    Grim-Reaper 3/4 ton status Author

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    Well if it turns in low then your part tiem. The reason it would roll if the tranny was in park and it was still part time is the case has a Diff in it. Just like a axle. If you lift one tire off the ground the open diff will let the tire with traction spin because the other tire can spin. Well if the front axle is dissconnected then yes the transmission is still in park but that front driveshaft can spin so the rear drive shaft can also spin through the diff.
    That make sense?
    As for why you can't get HI without LOC. Try pulling the shifter all the way back into High Loc. Then just bump it forward a notch and then try it. I find mine tends to get into the right possition better that way.
    The shifter tends to collect a lot of dirt over the years. It makes them hang and do funny things. They can be opened and cleaned. Just pay close attention how it came appart. There is about 10-12 parts in there counting shims and washers.
     
  8. R72K5

    R72K5 Banned

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    "The reason it would roll if the tranny was in park and it was still part time is the case has a Diff in it"

    that sentence lost me..
    not sure what you mean by stil part time, its apparently part time now cuz someone put in a kit, but wasnt before that. what does the kit do to the diff parts ? lock them together? but loc positions do that though, hmm..
    thanks
     
  9. monypit

    monypit Registered Member

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    Inside the 203 there is a set of gears just like a mini differential to split power between the front and rear in 4hi and 4lo. when you put it in hiloc or loloc it connects the front to rear directly. The draw back is that without the tcase locked you actually have one wheel drive with open diffs just like in 2wd with an open diff. The added bnefit to converting the 203 is you get a 2lo position but the main d=rawback is that you really need to operate it in 4wd about once a month or you will burn it up. It uses the chain for lubrication and in 2wd conversions that lubing isn't that good.
     
  10. Grim-Reaper

    Grim-Reaper 3/4 ton status Author

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    mony hit it. It's just like a axle with a open diff. Just look at the transfer case as a differential and the drive shafts as axle shafts. If you take a car with an open diff. When the axle is on jacks stands you can spin both wheels even though the transmission is in park. For park to work on a open diff both wheels have to be on the ground. If one wheel has no traction the other wheel can turn. Well a partime 203 is no different because it has a differential just like a axle. If one driveshaft has no resistance (hub unlocked so it's disconnected from the front wheels) then the other driveshaft can turn.
     
  11. Muddytazz

    Muddytazz 1 ton status

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    So it sounds like the fulltime was designed more for traction on everyday road use versus wheelin use. Or am i all wet? Would a part time actually be better for wheelin?
     
  12. Grim-Reaper

    Grim-Reaper 3/4 ton status Author

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    It was designed to let you use it on the street. The diff kept the drive line from binding. I have driven mine on ice and I was quite impressed how stable it was in full time. All my buds were sliding all over the place and mine pulled a straight line. Its great in the snow. Now if you need positive drive to both axles it will do it no problem.
    It has an undeserved bad rep. The majority of problems people have with the case they cause with things like miss matched tires. You have to keep them rotated and you have to replace all four as a set. Part tim conversions and not putting the case in lock to keep it lubricated. The rear out put bearings will run dry if you don't get it in lock.
    THe last being wear. The chain is spinning ALL the time. You can get about 150k out of a chain and hten it needs to be replaced or you can put in a chain saver kit to take the slack out and buy about 60k. Chain is $100 bucks or so plus gaskets and seals. There is no other transfer case that ran such a big chain. That chain is about double the width of a 208. The only case any stronger than it that was offered is the 205.
     
  13. Muddytazz

    Muddytazz 1 ton status

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    Reason i was asking is cause the 203 is in my burb and its my DD, I don't do much wheelin, but when i do, i really do or at least try LOL. When i bought it about 9 months ago, the odometer said 75K and the PO said its well over 200K everything is original, including the tired motor, (hoping its just the carb like yours LOL). I knew about if converted to part time having to run in Loc once a month to keep lubed.
     
  14. Grim-Reaper

    Grim-Reaper 3/4 ton status Author

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    Yeah it's probably due for a chain ($120 or so with seals). If it's still full time the easy way to check the chain is get it on a hill. Put it in low (not lock) Floor it. If the chain is loose you will here a bang as the chain jumps a tooth. Really I thought about swapping to a 205 but once I cleand up the shifter and replaced the chain I have not had any issues with mine. I'm about to swap to the better part time kit that replaces the shaft. The front and rear lockes has put a lot of stress on the part time kit. If you want to conver there is a replacement shaft for sale in the for sale section. Killer deal too.
     
  15. Muddytazz

    Muddytazz 1 ton status

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    I'm not looking to convert anytime soon. Kinda like the fact that all i have to do is move the stick and go. I will look into a chain replacement though, although i've never had any problems with this one....yet.
     

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