We chose the
MileMarker NP203 Shaft Kit for our case. MileMarker also offers a
light duty crown gear conversion kit, but we do not recommend it.
The case you will see pictures of in this article is actually being
converted from the crown gear style to the shaft style. Our 1975
Chevy Blazer had developed a clunk from the rear end when putting
it in gear. At first we suspected it was a u-joint. After checking
them we discovered it was from the transfer case. Closer inspection
revealed the crown gears had worn down, and were allowing about
1/8" to 1/4" of movement. Rather than replace the gears, we decided
to remove them completely.
The shaft kit is a one
piece unit which elimnates the spiders gears (or crown gears in our
case), the ring gear, and the tail shaft. This extreme duty unit,
if kept lubricated (as instructed above) correctly, it will easily
outlast the rest of your truck. I guarantee something else will
break before it does if you subject your truck to extreme
wheeling.
Start by
unbolting and removeing the tail cones. On most trucks you will
need a 1-5/16" socket to remove the yoke and a 9/16" socket to
remove the 14 tail cone bolts. Remove the outer tail cone first,
followed by the intermediate housing. You will then need to remove
the differential gear assembly. Don't panic! Needle bearings are
going to fall out. Don't let them fall into the transfer case!
Discard these bearings, as they are NOT reused. Refer to the
picture at the right. This is what your case should look like when
you get everything removed.
This picture
illustrates the difference between the assembled crown gear kit,
and the shaft kit. No screws, bolts, or moving parts to break on
the shaft kit. Both kits vary slightly for Dodge and Ford, as minor
differences in the t-case exist between manufactures, but the
basics are the same. Be sure to check the instructions in your kit
before you begin. I also recommend lightly oiling the shaft bearing
surfaces before installing it into the case.
Place the shaft
over the slpined shaft and gear on the t-case. Install the gasket
(lightly coat with RTV silcon sealer), and replace the intermediate
housing. Tighten all bolts, but do not overtighten, the tailhousing
is aluminum, and overtighting can crack it. Install the plastic oil
pump gear (you do have one on hand right?), the speedometer gear
and all ofthe factory shims. Replace the tail cone and install 2
oposing bolts and tighten. Do not yet install the rest of the
bolts.
Grab the rear of
the MileMarker shaft and push & pull on it. You should feel
some movement. This is called endplay. The instructions do
not specifically say how much, but it should move a perceptable
amount. Remove or add shims till you feel endplay. When done,
install the remaining bolts and tighten.
Here is the
completed unit. All that is needed now is to install the
driveshaft. Now is a good time to service those u-joints you've
been neglecting too! The transfer case shift pattern has now been
changed from HI-LOC, HI, NEUTRAL, LO, LO-LOC to 4HI, 2HI, N, 2LO,
4LO. The first thing we suggest you do is to lock your hubs and
drive about 10 miles. This will refill the oil catch at the back of
the t-case. Remeber to do this every few hundred miles!| Off-Road Products | Off-Road Motorsports | The Off-Road World | Off-Road News |
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