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my 78 k10 front Drive spins full time. Is that normal?

Discussion in 'GM Powertrain' started by jessafiddle, May 6, 2013.

  1. jessafiddle

    jessafiddle New Member

    Just got this 78 for 500 bucks, been sitting for 10 years, filled up the fluids and it fired right up, little sqeaky but ill get That worked out, can yall help me id the tranfer case, thanks, the front Drive spins full time and im wondering if thats normal

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    Last edited: May 6, 2013
  2. mfleetwood

    mfleetwood New Member ROTM Winner 1000 Posts

    Hi jessafiddle and welcome to the Club!! Congrats on your new ride too!

    I moved your thread to the Powertrain section of the forum as this will help in getting more opinions and responses.
  3. dsfloyd

    dsfloyd New Member ROTM Winner 1000 Posts

    Sorry I can't help with which tc it is but I know my front shaft spins full time. One way to see if there is a problem is to get all four tires off the ground and put it in drive. See if the front tires spin in 2wd (they shouldnt) and then again in 4wd.
  4. MrShorty

    MrShorty Moderator Staff Member 1000 Posts

    I could be wrong, but I thought there were basically 2 different transfer cases used in that time frame - NP 203 Full time 4wd or the NP205 part time 4wd. What are your shifter positions? traditional 2H-4H-4L-N or do you have Hloc-H-N-L-Lloc?

    From this site http://www.chuckschevytruckpages.com/drivetrains.html and looking at the position of the speedo cable and the fill hole, I would say you have the 203 full time case. It is normal for this case to spin the front driveshaft, as it sends power to the front and rear all the time.
  5. jessafiddle

    jessafiddle New Member




    'Seat' Hloc-H-N-L-Lloc 'dash'
  6. dsfloyd

    dsfloyd New Member ROTM Winner 1000 Posts

    Good call on the full time 4wd
  7. MrShorty

    MrShorty Moderator Staff Member 1000 Posts

    So it seems pretty sure that you have the full time 4wd NP 203 transfer case.

    Way back when I can recall helping my dad take our '75 203 apart to install the part time conversion kit. The 203 is big and heavy, but pretty simple in operation, too. In H and L, it is like having an open diff in the transfer case. power goes to both front and rear, but the differential in the t case allows the front and rear to spin at different speeds while turning. With open diffs, it also means that, when you have one wheel in the air, all the power goes to that wheel and you are stuck. In Hloc and Lloc, the center diff in the transfer case is locked, forcing both front and rear to spin at the same speeds.

    In many ways, I always like the basic idea of the full time 4wd like this. In particular, I thought it was nice to have the Low unlocked mode, which can be real useful for backing up trailers or other times when you want to gear reduction, but you don't necessarily need to lock the center diff.
  8. donl

    donl New Member

    It looks like someone has put on lockout hubs...or I am I just imagining that. There was a kit in the old days that used lockouts and pieces for the transfer case that turned the 203 in to a part time transfer case. The 203 was notorious for stretching the chain and then jumping in the case. Made a hell of a noise.

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