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NP203 and Manual Hubs Question

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by 79Cheyenne, Mar 19, 2000.

  1. 79Cheyenne

    79Cheyenne 1/2 ton status

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    My 79 was bought used(duh) and came with the stock driveline, I think. It has the NP203 with manual hubs. The hubs are aftermarket WARN. My question is: if I use the manual hubs with the NP203 do I need the part time conversion kit? and how would I check to see if it already has one? My main concern is that all of the part time kits say that you have to run with hubs locked one day a month to keep everything lubed, so if I don't have the kit am I OK with the manual hubs or do I need to run with them locked every now and then?


    P.S. thanks for the help with the missing engine(it was the vaccum advance hose)[​IMG]

    <font color=orange>1979 BLAZER Cheyenne[​IMG]
     
  2. Eric78K5

    Eric78K5 1/2 ton status

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    My 78 came the same way, and I don't have the part-time conversion kit. I lock my hubs at least once a month just to make sure the front axles get lubed, just to be safe. I don't know about checking for the part-time kit. Maybe jack up the front, put the transfer case in either 4-Hi or 4-Lo, and try turning the wheels. Like I said, I'm not sure. Hope this helps.
     
  3. Jason73K5

    Jason73K5 1/2 ton status

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    You don't need the part time kit for your setup. I run my '73 the same way. It is always good to engage everything and ensure that the system still works every once in a while if you don't go four wheeling regularly.
     
  4. Todd78/87

    Todd78/87 1/2 ton status

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    I thought you didn't need the kit when going from AUTO locking hubs,, but you did need it when going from FULL TIME hubs. I had the MileMarker conversion kit put in mine when I had the 203 rebuilt. If you don't use the conversion kit, wouldn't your front drive line still be engaged all the time? Granted, the wheels won't be driving unless you have your hubs locked in, but wouldn't the drive shaft?
    Someone clarify please.............................

    Todd 78/87[​IMG]
    [​IMG]
     
  5. Waxer

    Waxer 1/2 ton status Author

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    Yes, without the part time kit the entire front driveline will be turning, except the wheels. That means the gears will be moving, the axleshafts, the driveshaft. So you will still have some excess wear and it will take a little power from ya. Now, to tell if you have the kit or not, simply unlock the hubs and put her in 2HI and have a buddy look to see if the front driveshaft is turning when you drive down the street say at about 5mph. Try it in all teh shift positions actually, if the kit is installed then the driveshaft will only turn in 2 out of the 4 positions.
     
  6. Todd78/87

    Todd78/87 1/2 ton status

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    Thanks,, I thought that's how it worked.[​IMG]

    Todd 78/87[​IMG]
    [​IMG]
     
  7. EDdaTREE

    EDdaTREE 1/2 ton status

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    Okay, heres how you check for a p.t. kit-Put it in 4-HI or 4-LO with hubs unlocked, if truck moves, you have p.t. kit. If truck sits and spins frt. driveshaft,your case is still full-time,so you'll have to put it in 4-HI-LOC to run with hubs unlocked.This will spin everything except the frt. wheels so your rear t-case bearings and front axle gears WILL be lubed by the rotation of the chain and gears.Actually, this is not recommended by GM but me and other Ohio guys have run ours this way for years with no problems.We run full-time in winter weather(lock hubs and 4-HI for slick roads and 4-HI-LOC for real bad snow) Just remember that theres a lockable differential in the t-case that will ALWAYS send power to wherever is the easiest to spin unless you are in a LOC position.
     
  8. BillR

    BillR 1/2 ton status

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    Ok, I'm confused! My '79 is set up the same way. If I'm in HI (not HI-LOC) and the hubs are not locked in, why would the front driveshaft turn?
    If it DOES turn, then what does HI-LOC do differently?
    Fill me in, guys! This is my first 203.

    Blazin' in Flagstaff
     
  9. EDdaTREE

    EDdaTREE 1/2 ton status

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    If your 203 is still setup for fulltime 4wd,it
    will send power to wherever is easiest to spin
    UNLESS you put it in LOC.There's a differential in
    the T-case that allows for the difference of
    travel between frt.-rear tires in turns,the diff.
    locks up in 4HI-LOC or 4LO-LOC, thats why you
    don't run it locked on the street unless you have
    hubs that you can unlock or have the front
    driveshaft out.When I rebuilt my front shaft I had
    to run 4HI-LOC or the truck would sit and spin the
    front yoke. Hope that cleared it up for you. If not, just repost and I'll clarify.
     
  10. BillR

    BillR 1/2 ton status

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    I think I'm getting it. So, what does the installation of manual hubs accomplish, if it doesn't keep the front shaft from turning in HI (not HI-LOC)

    Blazin' in Flagstaff
     
  11. EDdaTREE

    EDdaTREE 1/2 ton status

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    Lockout hubs will give you more choices-almost like those newer full-time,part-time systems the yuppie scum have on tahoes, etc.4HI-LOC and hubs unlocked for dry roads or to take the stress off of a weak front knuckle u-joint. Even though the joint would still be spinning, it is'nt under tension because the hub is un-locked.The LOC positions lock the front and rear drivelines together, that's why you use LOC when wheelin'. If you ran with hubs locked, and in 4HI-LOC on dry pavement your t-case would eventually explode from the bind between frt.-rear.
     
  12. BillR

    BillR 1/2 ton status

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    OK, another question... When I have my hubs unlocked and the case is in HI, why can I still go just fine? When I put it in HI-LOC with the hubs locked, I get the 4WD light. Does this mean that I have the part-time kit installed?
    Thanks for your help on this!!

    Blazin' in Flagstaff
     
  13. EDdaTREE

    EDdaTREE 1/2 ton status

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    Yeah, there must be a kit already in it.You would DEFINITELY not be moving at all in 4-HI with hubs un-locked unless you have P.T. kit. The diff. in the 203 works just like an open axle diff.-tries to dump off power the easiest way possible,so the un-locked frt. shaft would just spin.DONT use LOC on pavement or wherever the wheels can't slip though.
     

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