Matt Gieselman | NP200 Transfer Case Rebuild

NP200 Transfer Case Rebuild

Here is an outline of my rebuild with notes. 

Special thanks to Damien Civiello who loaned me the spacer necessary for setting up the idler gear pre load and shared what he learned during his rebuild.  His forum post can be found here.

Parts and Supplies Required:

  • Power Train manual, I wouldn’t start without it (Hard copy available from Faxon Auto Literature, digital copy available from Military Manuals)
  • NP200 Rebuild Kit (TCK-200 from DC Trucks, $255 shipped.)
    If you want to buy parts ala cart here are the numbers:
    • Yoke seals - National 410308 x 4 (Double lip, double case heavy duty), Redi-Sleeve 99212 x 4
    • Shift shaft seals – National 6835S x 2, Redi-Sleeve 99076 x 2
    • Idler bearings – National 2793 & 2720
    • Output shaft bearings – National 3720, 2793, 3780 & 2720
    • Low gear roller bearing – National C1960Q
    • Output shaft pilot bearing - QBR23549
  • Shim Pack (McMaster-Carr, part number 3088A939, the shims included in the rebuild kit doesn’t have all the sizes needed.)
  • Anaerobic Gasket Maker (Permatex)
  • RTV Silicone Gasket Maker (Permatex, used on the shift shaft seals and to seal the yoke splines to prevent leakage around the shafts.)
  • Thread Sealer (Permatex, used on studs that go through to the inside of the transfer case.)
  • Mechanics wire, approximately 0.03" (Harbor Freight, stainless so it won't rust.)
  • Glyptol (If you plan on blasting the inside this is the sealant to use, $50 from Eastwood.)
  • Stainless steel shift shafts (M Series Rebuild, $100 each x 2)
  • Hardened hi/low thrust washer (M Series Rebuild, $100)

Tools Required:

  • 2 Jaw Puller for removing the yokes.
  • Press for bearing removal and bearing/race installation.
  • Bearing race and seal driver. (Harbor Freight, the kit doesn’t include a race driver for the larger race in the NP200 so I just ground down one of the old races and used that to seat them.)
  • Brass drift. (Harbor Freight, used to drive out the old races.)
  • Torque wrench in the 140-160 foot pounds range.
  • Torque wrench in the 15-30 inch pounds range. (I bought Park Tool TW-1 $35, cheap and accurate.)
  • 1 5/16” socket for removing the slotted yoke nuts.
  • Spanner Pin wrench for holding the yokes when tightening the yoke nuts.
  • Idler Gear Dummy Shaft (Quad 4x4 sells T2013, it’s useful for removal of the idler shaft but it’s too long to fit in the case when doing the installation, so a socket and extension will work just as well for removal.)
  • Spacer for setting idler gear bearing pre load.

NP200 schematic:

np200 diagram

Transfer Case - 03

 

Transfer Case - 05


Transfer Case - 08

The case had 55+ years of oil and dirt stuck to it, pressure washing only got it about half way clean.  A combination of a putty knife, parts washer and hot water with degreaser finished the job.

This took longer than expected, I’m not sure if there is a better way to remove the dirt and oil.
 Transfer Case - 21 2 jaw puller removing output shaft yoke.
Transfer Case - 23  
Transfer Case - 32  
Transfer Case - 35 Input shaft, shift fork and idler gear.
Transfer Case - 37 Shift shaft spring and poppet.
Transfer Case - 38 Shift fork, you can see the lock wire holding the set bolt in place.
Transfer Case - 39 Input shaft.
Transfer Case - 42 Shift fork.

Transfer Case - 47

Transfer Case - 49

The two speed clutch gear, inner and outer teeth were fairly chewed up which explained why the shift forks had gouges as the operator would push harder and harder to get the transfer case into hi/low.
       Transfer Case - 50               Eastwood’s 2 part epoxy primer applied to the cleaned, blasted and cleaned again parts.

The primer sprayed on easily and I was pleased with the results.
Transfer Case - 51  
Transfer Case - 52  
Transfer Case - 53  
Transfer Case - 54  
Transfer Case - 56 I used Eastwood’s 2K Chassis Black Satin for the top coat, so far it seems pretty durable.
Transfer Case - 67 Assembly begins with installation of the idler gear, then the input shaft as shown on the left.
Transfer Case - 68 Output shaft installed.
Transfer Case - 70 Removing the installation lip from a Redi-Sleeve, the yoke had a groove worn in it from the original seal, the Redi-Sleeve is stainless steel and provides a perfect sealing surface.

A little anaerobic gasket maker under the sleeve fills the groove so the Redi-Sleeve won’t deform.
Transfer Case - 71  
Transfer Case - 72  
Transfer Case - 76 The mostly finished product.
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