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More driveline problems

Discussion in 'The Garage' started by PerdidoK5, Apr 11, 2004.

  1. PerdidoK5

    PerdidoK5 1/2 ton status

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    Just to recap, last week I got some good tech. support here and discovered the gears in my rear end (12 bolt) were in a thousand pieces. I changed those gears (spiders, and associated) with great anticipation of getting my truck going again. I got everything together, added fluids, and went for a drive. I didn't get a quarter mile before I heard something break, I went back to the house and looked under the truck: the front driveshaft to diff. u-joint had broken and the driveshaft was flopping around. I unbolted the front shaft from the flange and drove it again. This time I never even got off of my road, something else kinda popped and I lost power to the wheels. Any gear, any range. Not really knowing what to do, I got a new u-joint and hardware and re-installed the front shaft. (I don't know why I thought this would work but at the time it made sense). Now the truck still won't move. I have two questions come to mind. First, when I reinstalled both driveshafts during the week, my allignment marks had rubbed off, so niether shaft is probably in the way it came out. Second, when my front u-joint broke, could I have broken the chain in my NP203? I'm still trying to learn about the truck and have only had it a couple years. It's never been my daily driver, but I would like it to be. It needs a lot of attention. It's been neglected over it's 25 year life and I want to fix it right. Sorry so long, I always do that. Hope you may have some advise. Thanks.
     
  2. 84_Chevy_K10

    84_Chevy_K10 Banned

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    Make sure your transfer case is in gear.
     
  3. PerdidoK5

    PerdidoK5 1/2 ton status

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    I put the transfer case in every position, no luck. I can kinda "feel" the truck go in gear though, very softly. There is a little grinding noise when I put it back in park, not too bad.
     
  4. 84_Chevy_K10

    84_Chevy_K10 Banned

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    I think your shift linkage probably needs adjustment. It sounds to me that your transfer case is in neutral.

    The NP 203 is a major PITA to mess with. I've never owned one but I'm sure a member that has will post up and tell ya how to get it right so you can get your case back into gear.
     
  5. PerdidoK5

    PerdidoK5 1/2 ton status

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    Man,I hope it's not inside the case. /forums/images/graemlins/weld.gif
     
  6. 84_Chevy_K10

    84_Chevy_K10 Banned

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    If it is you should be able to find NP 203s for a TH 350 for $50 all day long.
     
  7. PerdidoK5

    PerdidoK5 1/2 ton status

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    [ QUOTE ]
    If it is you should be able to find NP 203s for a TH 350 for $50 all day long.

    [/ QUOTE ]

    Really? I hope so!... So is that what I need to do, adjust the linkage? Anyone know how? /forums/images/graemlins/dunno.gif
     
  8. ilikemud

    ilikemud 1/2 ton status

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    when i lifted my truck 350/350/203 i had to get a new front driveshaft made, being it was my daily driver i thought i could just take the front shaft out til i got some cash for a new one, but when it was out i could feel it shift into gear but not go, (sounded like chain slipping...) but as soon as i put in the new shaft all was well again... dont know if this helps, but good luck
     
  9. v-3500

    v-3500 Registered Member

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    Sounds to me like the rear diff, you just had rebuilt, blew out on you again. Forget the transfer case (through it in 2H) and remove front drive shaft for now, and concentrate on getting your rear diff, drive shaft and transmission working.

    It is hard to find a competent person to rebuild differentials. Getting the feel for setting backlash and properly loading the side bearings takes time and experience to get.
     
  10. PerdidoK5

    PerdidoK5 1/2 ton status

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    So, I have one for the shift linkage at the transfer case and one for the rear diff. being messed up again. What are the marks for when removing the drive shafts? Balance? I didn't hire anyone to put the gears in my diff. I put them in myself, first time, Wasn't hard but I know nothing about adjusting the tolerances.
     
  11. PerdidoK5

    PerdidoK5 1/2 ton status

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    Mine does the same thing, no front shaft, no drive at all. Thanks, I thought that might be a part of the problem, perhaps it's normal. I just want to drive my truck! /forums/images/graemlins/angryfire.gif
     
  12. v-3500

    v-3500 Registered Member

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    Sooooo, you put together a differential without setting the pinion depth, backlash, and side bearing loads? That explains a lot!
     
  13. PerdidoK5

    PerdidoK5 1/2 ton status

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    Well, I'm glad it explains something . Do I need to start over, disassemble the diff., set the tolerances. Or is that beyond my humble abilities? /forums/images/graemlins/dunno.gif
     
  14. v-3500

    v-3500 Registered Member

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    Tow your truck to a professional...throw the transfer case in 2H, and remove the front drive shaft before you do it. Tell them to rebuild your rear differential. It is going to be a while before you are going four-wheeling, but at least after they rebuild your rear diff it will be drivable on the street in two-wheel drive only.
     
  15. tRustyK5

    tRustyK5 Big meanie Staff Member Super Moderator GMOTM Winner Author

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    OK let's recap.

    You have an NP203 T-case which sounds like it hasn't been converted to part time.

    You swapped new gears and 'stuff' into your 12 bolt.

    First off, regarding the 12 bolt, depending on exactly what you replaced you may have wasted time and money on that. Each component has to be adjusted into a very narrow tolerance range to work correctly. Pinion depth, pinion bearing pre-load, backlash, and correct meshing pattern...all of those things have to be measured carefully and be within a very narrow range of tolerances.

    I suspect your work inside the diff self destructed when you went for a drive. When a major driveline parts breaks on an all wheel drive vehicle it can cause breakage elsewhere, and in your case it sounds like the front U-joint was the weak point.

    Once you remove the front shaft on an unconverted 203 all the power will go to the front output and the truck will not move.

    So, what exactly did you replace in the 12 bolt? If it was just spider gears it shouldn't have been a big deal. If it was a new ring and pinion and bearings you could have a diff full of shrapnel again.

    I'd guess your T-case works just fine, and the linkage is probably fine too.

    Rene
     
  16. 84_Chevy_K10

    84_Chevy_K10 Banned

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    There is no such thing as 2 high with an NP 203.
     
  17. v-3500

    v-3500 Registered Member

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    My bad! I did not get the part about the older full-time NP 203 transfer case and hubs. Nix the "remove front drive shaft" idea...
     
  18. PerdidoK5

    PerdidoK5 1/2 ton status

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    I replaced the spider gears and the gears that slip on to the axle shafts to form the rectangle as you look into the diff.(4 gears) they are not new, I got them from another 12 bolt. I did not replace the ring and pinion. I didn't mess with them at all. /forums/images/graemlins/thinking.gif
     
  19. PerdidoK5

    PerdidoK5 1/2 ton status

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