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NP203 Linkage Adjustment

Discussion in 'The Garage' started by PerdidoK5, Apr 12, 2004.

  1. PerdidoK5

    PerdidoK5 1/2 ton status

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    I have an NP203 (not converted) in a '79 K5 going to GM 12 bolt axles (Full time FWD). I hear a grinding noise when putting the TH350 in Park, and am not able to get any gear to engage Forward (L1,L2,D) or Reverse. I get no change in behavior no matter where the range selector is positioned, and I can feel a slight "thump" when I select a gear. Now, before I go dropping the Transfer Case or opening up my differential, does anyone know how to check the linkage for proper adjustment on the NP203? /forums/images/graemlins/dunno.gif
     
  2. PerdidoK5

    PerdidoK5 1/2 ton status

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    No one has any ideas? /forums/images/graemlins/frown.gif
     
  3. Muddytazz

    Muddytazz 1 ton status

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    Look at the bottom side of the shift(where the rail connect to). You have to line up the two holes by putting a nail or drill bit in them, then adjust the shifter rails /forums/images/graemlins/thumb.gif
     
  4. bouncytruck

    bouncytruck 1/2 ton status

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    I have a TH350/NP203 (part-time). I had a grinding noise when I would put it in park too, sometimes going into other gears and when switching the transfer case. I thought it might be the t-case chain. It turned out to be the reverse sprag in the tranny exploding and all the little bearings grinding their way around inside the case. It only happened a few times before I pulled it apart, but it was enough to do some serious damage, including cracking the transmission case.
     
  5. PerdidoK5

    PerdidoK5 1/2 ton status

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    Would I be able to tell anything by dropping the transmision pan? Would debris be in there if that is the problem? How much does a TH350 rebuild generally cost?
     
  6. southernspeed

    southernspeed 1/2 ton status GMOTM Winner

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    I'd check your t/case first before getting in deep. Check the adjustment. Also try jacking up the rear axle, put the t/case in lock and turn the rear prop. With the front wheels on the ground you shouldn't be able to turn it. If it's turning(and your t/case is adjusted right I reckon you've either blown the centre diff or the chain. You can drain the oil and remove the round rear facing cover on the t/case to check the chain and look for diff bits. Post what you find...I'd be interested to know as I run the same set up. Good luck, /forums/images/graemlins/thumb.gif
     
  7. PerdidoK5

    PerdidoK5 1/2 ton status

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    That sounds like a good place to start. I'll jack it up and perform the test you mentioned. (I was wondering how to tell if the chain is busted or not without opening the case). If the wheels DONT turn, I will assume the driveline is sound and the transmission is the problem? Is your setup converted to part time?
     
  8. southernspeed

    southernspeed 1/2 ton status GMOTM Winner

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    No, I've kept mine full time as I really like being able to run it with the t/case NOT in lock when I'm on really slippery clay and mud and on snow. My '91 is part time and when I HAVE to lock it up on clat etc it really pushes the front. Lot of people don't like 203's in full time but they have their advantages. All depends what you're going to be doing with it I guess! /forums/images/graemlins/thumb.gif
     

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