249 to 242 Swap, by Wes (Solitude)

in Technical Jeep Modification Articles


NP249 :
NP242 Conversion
Written By: Brian Wesley
Free
AKA: “SOLITUDE”

TOOLS NEEDED:
#1 Screw Extractor (It’s a type of “Easy Out”)
10″ Monkey Wrench
8mm Socket & Crescent Wrench
10mm Socket
13mm Socket
14mm Socket
15mm Socket
18mm Socket & Crescent Wrench
5/32 Punch
9/16 Crescent Wrench (Buy a cheap one, this will be hacked)
9/16 Deep-Well Socket
Crowbar
Flat Head Screw Driver
Phillips Head Screw Driver
Rubber Mallet
Hammer
RTV
Gasket Remover or Razor Blade
Bottle Jack
Jack Stand
NP242
Safety Glasses (Stuff WILL fall in your face & eyes)
Snap Ring Pliers (GOOD ones, Spend some money)
Vise Grips

My 1993 Jeep Grand Cherokee
V8 5.2

BEFORE YOU START:

Do your homework. I tried to make this write-up as conclusive as
possible, but there is probably something I left out. This is
not a factory service manual; do not treat it as such. This is
just from my personal experience. I am not an employee of any
off-road shop, parts distributor or parts manufacturer. I am a
simple off-road enthusiast. This was done in my driveway, by my
friends and me, your shade tree mechanics.

I swapped a NP242 from a 1991 Jeep Cherokee (XJ) into my Jeep
Grand Cherokee (ZJ) with a NP249. The goal of this swap is to
have the following capabilities: 2WD, 4 Part-Time, 4 Full-Time,
neutral, 4-Low. I also wanted to do this swap because the 93-95
NP249 does NOT lock 50/50 in 4-Low. If you have a NVP249 from a
96-98 ZJ it DOES lock 50/50 in 4-Low. To make everything mate
and mesh you have to remove the input gear from your NP249 and
put into your NP242.

STEP ONE:
Safety

Chock your wheels, chock your wheels, chock your wheels. This
means, put something in front and behind your wheels to keep
your Jeep from rolling and moving any direction. Disconnect the
Negative cable from the battery. Get in put it into neutral and
pull the handbrake.

STEP TWO:
Removing the front and rear driveshafts.

The rear is connected to the differential with four(4) 8mm
bolts. Unbolt these, and then slide the driveshaft out of the
tailshaft of the transfer case.




The front driveshaft is connected in two places. Start by
unbolting the four(4) 8mm bolts on the transfer case, then
remove the four(4) 8mm bolts on the differential. Compress the
front driveshaft, and slide it out.


STEP THREE:
Removing the crossmember and supporting the transmission.

Start by supporting the transmission. Using a bottle jack or
floor jack place the top of the jack right behind the
transmission pan.

Remove the four(4) bolts supporting the crossmember.

Remove the bolt running through the bushing that supports the
transmission on the crossmember. After removing the crossmember
support the transmission using the jackstand under the bushing
housing.

STEP FOUR:
Drain the transfer case. This is where your monkey wrench comes
in handy. Notice the plugs.

STEP FIVE:
Removing the transfer case.

Disconnect all the connections to the transfer case. The shifter
linkage (The rod with the plastic bushing. It pushes through)
and the electrical connectors, speedometer and VIC.

There are six(6) bolts holding the transfer case in place. You
can’t miss them. The first five(5) are easy to remove. The sixth
one is on the top passenger side, it is a complete PITA. This is
where your donor 9/16 crescent wrench comes in handy (And some
of my redneck engineering). There is not enough clearance for
you to put a full size 9/16 or even to use a socket. I had to
cut the open end off of the wrench and notch the end to attach a
piece of rope (The wrench ended up being a little longer than
4″. Napa – $3.50 for wrench, $5.00 for some guy to cut it up).
Loop the rope over the case and pull from the driver’s side. It
took both my friend and I to break this nut. (My knots: bowline
on the crescent wrench end and two half hitches on the pipe
wrench end. I didn’t feel like busting it on account of my
knots.)




This will take some effort. You need some muscle for this, or a
really nice jack. I had the muscle and no jack. This takes two
people. Both you and a friend need to wiggle the transfer case
till you clear the bolts. If you have a creeper it will make
things easier for you and him. Remove the case and place it on
the creeper to pull it out from under the Jeep. I didn’t have a
creeper so my friend and I used a thick towel and placed the
case on it to slide it out from under. Have a bucket ready. When
you remove the case, a little transmission fluid will leak out
of the transmission, so be prepared.
THIS CASE WEIGHS ALMOST 100 POUNDS, BE CAREFUL! I bench 225,
this case is very big and awkward to maneuver so make sure you
have everything in place and a plan between you and a friend,
before you try to take it out.

The cases side by side. NP249 Left. NP242 Right. Note: I have
yet to clean up the NP242.


Take a look at the inputs’:
NP242




NP249


Before I cleaned up the NP242:


After:

Side-by-Side:

STEP SIX:
Breaking the case.

Start by removing the Speedometer gear so you don’t damage it.



Remove the input seal and housing. It is RTV’ed. Then remove the
snap ring on the input shaft. (Sorry bad picture. It is not the
big obvious snap ring. It’s the smaller one closer to the input
gear.)

Next remove the three(3) bolts holding the back half of the
tailshaft in place. This is also RTV’ed.


Next remove the snap ring completely from the mainshaft.

Remove the four(4) bolts holding the front half of the tailshaft
in place. It’s RTV’ed. Finally you get to pull the tailshaft
off.

The next few pictures are pretty self explanatory.


Now you get to remove the back case half. Remove all the bolts
holding it together. It is RTV’ed. Get out your flat head screw
driver or crowbar. There are two outlets built into this case to
help you break the RTV seal. One on both sides of the case.

Now remove the back case half.

(Take note to where everything is located so you can put it all
back together correctly.)

Remove the chain just like you would on your bike. It’s pretty
simple.

Remove the mainshaft. This is what it should look like to this
point.

Now to remove the shifter assembly (Inside the case). By the
shifter there is a small rubber plug. Remove this plug and use a
#1 screw type extractor to remove the low range shift fork
rollpin. Tap the extractor into the end of the rollpin, and with
vice grips on the extractor pull and twist in a
counterclockwise
direction to remove the rollpin. It may take 2 or three tries to
remove the rollpin. If you cannot get the screw extractor to
“bite”, I had to drill out the rollpin, essentially shredding
the rollpin inside the shaft. Then I punched what was left of it
through with the 5/32 punch. You’re going to have to go pick up
another rollpin if you go this route. Pay special attention to
the flats on the shaft when you remove it so you get it back in
the same way. When you put this back together you’ll need to
reinstall this rollpin.

Give the input a slight tap and:

STEP SEVEN:
Remove the input gear out of the NP249. It’s pretty much the
same process as described above. With a few exceptions.
The tailshaft is one(1) piece on the NP249. This is where to
access the snap ring. And you won’t have to remove the rollpin
on this one.

The input shaft I pulled from the NP242 on the left. Compared to
the input gear that came out of the NP249 which is going
into the NP242.

STEP EIGHT:
Put it all back together in the reverse process with your new
input gear in the NP242. Make sure to clean out the inside of
the NP242 before you put it back together. Clean all the
surfaces with your gasket remover or razor and be very liberal
with your RTV application (LOTS). Make sure to tighten
everything down. Make sure to add one(1) quart of ATF or
Differential Gear Lube to the case before you crank it up. I
chose to use some AMSOil. Good stuff. Adjust your shifter
linkage for the new case and you should be ready to roll!





Hope this helps anyone interested in performing the swap. If you
have any questions don’t hesitate to ask. If you do a swap using
my write-up as reference, please, email me and let me know.

[email protected]
. Good luck!

All
information provided herein ‘ 2010 KevinsOffroad.com. All rights reserved.

"Jeep" is a registered trademark of the Chrysler Company.

{ 1 comment… read it below or add one }

Kevin's Offroad May 31, 2012 at 3:00 am

249 to 242 Swap, by Wes (Solitude) http://t.co/KlscVBT5

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