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4 wheel shifter

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by zach78k5, Mar 23, 2001.

  1. zach78k5

    zach78k5 1/2 ton status

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    my question concerns the 4 wheel shifter.i have manual hubs on my blazer. my shifter has Low lock, high lock, high and low. i understand low and high lock are for 4wheel drive, and high is just 2 wheel drive so my driveline in front isnt spinning. what is low for. i assume this is 2 low. what for? if i put big ass tires on could i use 2 low all the time?
    NOW FOR MY REAL QUESTION
    my brother has a 75 with automatic hubs. he has full time 4 wheel drive. however he has the same shifter as me. low lock, low, high, high lock. what for. the truck is always in 4 wheel drive, as far as i can tell. i know for sure the hubs are always locked. why have a low lock and high lock, or low and high. there should only need to be 2 settings for him because the hubs are always locked. if someone could explain all this i would be very greatful. thanks
     
  2. thatK30guy

    thatK30guy 1 ton status Premium Member

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    Sounds like both of you guys have the NP 203 t-case. Also sounds like one of them has been converted to part-time with the little conversion kit you see at the parts stores. With a full-time 4x4 vehicle, the front gears and driveshaft will ALWAYS spin, no matter what, until you convert it over to part-time, and then it will stop spinning.
     
  3. muddin4fun

    muddin4fun 3/4 ton status

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    Well, hi is for driving around in 2wheel drive like in the city. hi-lock good for having 4wheel drive when you're on a trail and not needing a bunch of tork but you need the front spinning. The low lock is good for rock crawling, going up or down steep grades and for when you get stuck. lo, well i haven't found much use for that.

    [​IMG]


    <A target="_blank" HREF=http://muddin4fun.coloradok5.com>http://muddin4fun.coloradok5.com</A>
     
  4. zach78k5

    zach78k5 1/2 ton status

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    i understand how the full time and part time work. my setup is great. i am questioning my brothers full time 4 wheel drive with the 4 position shifter though. does it sound like his was converted to full time or what? thanks
     
  5. MudRebel350

    MudRebel350 1/2 ton status

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    It comes full time from the factory, it sounds like yours was converted to part time cause full time is just a waste of gas and front axle parts and such.

    JD
     
  6. thatK30guy

    thatK30guy 1 ton status Premium Member

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    MudRebel350 is pretty much on the money here. Take it from him, full time IS a waste of gas. AND, it causes the front parts to wear out FAST. I had a few full time vehicles and drove them for awhile before the front axle shaft splines stripped, causing the whole thing to sit like a dead duck and just spin the front shaft while in gear. Had to take the front shaft off, and lock it in 4 Hi just to get it around. When I did this, it was like driving a regular part time truck again. So, I fixed the worn parts by replacing and converting the t-case to part time and never had problems again.
     
  7. MudRebel350

    MudRebel350 1/2 ton status

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    I never owned a full time truck but my moms landcruiser which is full time needed to get some stuff replaced a while back casue of the full time 4wd part wear-out system. K5s get bad gas mileage as it is too, ya know.

    JD
     
  8. zach78k5

    zach78k5 1/2 ton status

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    i guess what i am really trying to figure is why the 4 position shifter for a truck with full time 4 wheel? it is always in lock and always in 4. i could see having low but the others seem useless. what do the other 2 positions do?
     
  9. Goose

    Goose 1/2 ton status

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    Okay, you and your brother both have the NP203 transfer case. This is a full time unit with a differential in it like a front or rear differential. Power is always split front and rear and will go to the drive shaft (and therefore axle) with the least traction just like an open differential in an axle. Like one tire spinning in wet grass. This is how the NP203 works in High or Low position. In High Lock and Low Lock there is no differentiation. It locks the front and rear drive shafts together so power is split 50/50. Just like adding a true locking "differential" to an axle. The front hubs will be what are called "drive axles". There isn't a mechanism to lock or unlock the hubs, manually or automatically.

    When the NP203 is converted to part time, the spider gears in the transfer case are replaced by a solid unit thereby doing away with the differential. Also, the drive axles or drive hubs are swapped for manual or automatic locking hubs.

    So...
    NP203: full time transfer case with differential when in high and low and no differential when in high lock or low lock

    NP203 converted: part time transfer case with a 2 wheel drive high and low and also a 4 wheel drive high and low (without differential)

    Manual hub: used with part time transfer case
    Locks the front axle to the hub which turns the tire (you have to manually turn the hub to lock it)
    Automatic hub: used with part time transfer case
    locks the front axle to the hub (hub will automatically lock in theory)
    Drive hub or drive axle: used with full time transfer case
    hub is constantly locked with the axle

    [​IMG]
     
  10. thatK30guy

    thatK30guy 1 ton status Premium Member

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    Well done, Bruce! Couldn't have said it any better.
     
  11. mudhog

    mudhog THEGAME Staff Member Super Moderator

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    very well put

    77blazer see it at<A target="_blank" HREF=http://community.webshots.com/user/ssmith6333>http://community.webshots.com/user/ssmith6333</A>[​IMG]
     
  12. Goose

    Goose 1/2 ton status

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    Thanks guys.

    [​IMG]
     
  13. mudhog

    mudhog THEGAME Staff Member Super Moderator

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    no problem that was an awesome explanation i think even my 6&7 year old boys could understand how that works now lol

    77blazer see it at<A target="_blank" HREF=http://community.webshots.com/user/ssmith6333>http://community.webshots.com/user/ssmith6333</A>[​IMG]
     

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