Assembly: Main Case |
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My first step in assembling the transfer case was to insert the
underdrive/direct shift rod in the case. Make sure the direction
is correct with the shift lever notch outside of the case. While
sliding the rod into place slide it through the underdrive/direct
shift fork (the larger of the two forks.) The set screw hole should
face away from the intermediate shaft as pictured. After tightening
the set screw install the safety wire through the set screw. Some
models may not have a hole in the set screw for the safety wire - you
might consider using Loc-tite on the screw in this case. The white
'goo' you see in almost all of the pictures is an engine assembly lube
I purchased at the local NAPA store.
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The next step was to install the two gears that ride on the main
output shaft. After coating everything with the assembly lube I
fit the two gears together and then slid the big gear onto the shift
fork. Notice that the fork groove is towards the rear of the case.
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Before installing the output shaft into the case I first installed
the rear bearing cone. As recommended I used the inner race from the
old bearing set to drive the new bearing onto the shaft. A brass
hammer worked great for this. Turn the old race 'backward' with the
smaller end against the new bearing. Firmly strike the old race with
the hammer, working around the bearing (meaning don't just hit it on
one side) until it is completely seated on the shaft. A shop press
would work nice for this if you have access to one. Then just slide
the shaft into the rear of the case and through the gears until the
shoulder makes contact with the front output gear.
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There are 10 splines on the front end of the output shaft - two of the
'valleys' are longer than the other six and are opposite each other.
The notches of the output shaft thrust washer fit into these extended
notches as pictured. After installing the thrust washer a snap-ring
is installed. If you have the proper snap-ring tool life will be much
easier at this point. Since I don't have the proper tool I had to
improvise. I first got the snap-ring started onto the shaft by hand -
that didn't require much effort. Wedging a small screwdriver (a
screwdriver would be safer - I used my pocket knife) into the gap
helped spread it enough to slide it down to the next shoulder.
Here I used a small open-end wrench to lever the ring onto the next
'level'. Once there, the gap was large enough for my piston ring
installation tool to grab so I used it to help slide it the rest of the
way to its groove. Make sure the snap-ring is fully seated in its
groove. I had one spot in the groove that had a small burr that I was
unable to remove. This kept the snap-ring from seating at that point
so I had to make sure that the burr wound up in the gap of the
snap-ring. You'll thank yourself later if you will inspect this
groove prior to beginning assembly by running the snap-ring around
the groove first to detect any problems. The front output bearing
cone may then be installed - this may require supporting the other
end of the shaft and driving the cone on in a similar fashion to the
rear bearing cone. One last tip - the front output shaft bushing is
supposed to have an internal diameter of 0.627" (just over 5/8".)
If this bushing has an internal diameter over 0.630" it should be
replaced - which will require having the new bushing reamed. My new
front output shaft had a diameter of 0.624" so it looks like there
should be about 0.003" clearance for a proper fit.
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The next step was to install the front bearing race into the case.
Since the front bearing cap has a 'lip' that contacts this race it
will be recessed slightly into the case. I tapped the race in until
it was flush to the case. Install the cap, with gasket (without the
gasket you will be unable to properly set the shaft endplay.) Use a
crisscross bolt tightening process in order to keep the bearing race
from being forced crooked. No sealer was used on the gasket at this
time since the cap will have to be removed later to install its
components.
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My next step was to install the rear bearing cap - leaving the
speedometer components out for now. Be sure you have enough shims
installed - too few can result in damaged bearings! A simple way
to pre-determine the number of shims to use is to install the rear
bearing race and 'snug' it to the bearing cone. Place the rear
bearing cap onto the race (there is a groove in the cap for this
purpose) and then measure the gap between the case and the cap. Add
0.010" to this measurement and that should be your starting shim pack.
Install the cap and tighten the four bolts.
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At this point in the assembly process it would be a good idea to
double-check the operation of the installed shift rod. Install a
poppet ball and spring into the appropriate location on the front
bearing cap. Only tighten the retaining plug just enough to hold
everything in place. If you go too far you won't be able to 'shift'
the rod by hand. I found that just one or two turns on the plug is
enough. This allows you to still 'feel' when the ball seats into
one of the three shift positions but still is easy to 'shift' with
your hand.
High Gear: Pull the shift rod forward (away from the case)
until the poppet ball 'clicks' into place. If everything is fine
things should look like the top picture at left. The sliding gear
should completely mesh with the 'chevrons' of the front output gear.
Rotate the shaft using the sliding gear and try holding the front
output gear stationary with your other hand. You shouldn't be able
to do this. Don't 'spin' the shaft unless you have lubricated the
bearings!
Neutral: Push the shift rod in until the poppet ball
'clicks' into the next location. At this point things should resemble
the second picture to the left. This time when you try to turn the
shaft with the sliding gear and holding the front output gear steady
it should. The sliding gear should have moved far enough back to
'release' the chevrons of the other gear allowing it to 'free-wheel'.
Low Gear: Push the shift rod in until the poppet ball
'clicks' into the last position. At this point things should resemble
the third picture to the left. The front output gear should still
'free-wheel' as it did in Neutral. A final check of this position
will need to be made after the installation of the intermediate gear.
If any of the above positions don't seem to work right stop and
verify that everything has been installed correctly before continuing.
Since the endplay of the output shaft has not been properly adjusted
at this point there is a remote chance that a gear may drag. If
no other problem can be found to cause such a dragging go ahead and
adjust the endplay - if there is still a problem even after adjusting
the endplay something is still wrong so stop and check things again.
I did the above checks before checking the endplay because if there
was a problem I didn't want to have to then fix the problem and then
go through the whole endplay adjustment again.
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Adjusting the endplay is fairly straightforward using a dial
indicator as pictured. Adjustment is made by adding (increases
endplay) or removing (decreases endplay) shims. The service manual
recommends an endplay of 0.004" to 0.008". Novak recommends 0.002"
to 0.006". I ended up with an endplay of 0.004" on this case.
After removing and replacing the rear bearing cap you may find it
necessary to re-seat the rear bearing. This can be done by tapping
on a wooden dowel on the front end of the output shaft. If 'tapped'
too hard it is possible to damage the rear bearing rollers. Novak
recommends in their rebuild instructions to tap on the rear bearing
cap. They claim the inertia generated by this will seat the bearing.
I haven't tried this as I didn't read those instructions until after
finishing the assembly. I'll give it a try on the next case...
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In installing the needle bearings for the 1.25" intermediate shaft I
found this procedure worked well. 1) Slide a punch through the small
lubricating holes in the gear as pictured. 2) Place one of the
spacer rings on top of the shaft and around a wooden dowel (dowel needs
to be sized slightly smaller than 1.25".) 3) Run a bead of assembly
lube in the gap between the dowel and gear. 4) Slide the needle
bearings into the gap. The dowel will keep the needle bearings from
completely falling over and the supported spacer will keep things
roughly level. After finishing installing the 24th needle bearing
place the second spacer on top of the bearings and turn the whole
thing over. Remove the punch and let the dowel slide the rest of the
way into the gear. Install the remaining 24 needle bearings as
above and top them off with the third and final spacer. The dowel
could be safely removed at this point but I left it in to guarantee
that the needle bearings would stay where they belong. If you choose
to leave the dowel in place be sure it is slightly shorter than the
gear.
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This is a photo of the intermediate shaft that I bought from Novak.
This shaft has a groove for an O-ring seal on each end of the shaft.
The complete kit has the shaft, two O-rings, thrust washers, output
shaft thrust washer, output shaft snap ring, 48 needle bearings, plus
instructions. For some reason I think the kit I received had the
front output shaft snap-ring as well as the poppet balls but I don't
remember now.
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Copyright © 2002 David Hoelzeman
Last Updated: January 24, 2002 |
