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View Full Version : Transfercase Swap and Rubicon Express Hack 'n Tap SYE Install



2000XJ
10-13-2009, 01:00 AM
Alright, so I finally have some time to sit down and do a write-up on the transfercase swap, and Rubicon Express HnT Install. It's really simple, and some of you guys may already know how to do this with your eyes closed, but I wanted to post this up for those who may have never done something like this.

This write-up can be applied to both the NP242 and NP231, as they mount up in the exact same way. The Hack 'n Tap process is a bit different for pre-'96 XJ's, but is the same for either the NP231 or NP242 for '97+ model years.

Essentially, it's a breeze. This is the first time that I've swapped a tcase on an XJ, but I've removed and reinstalled them various times on TJ's, so this was not very different.

I tried to get as many pictures as possible, but it was just pretty hard to do as I did this job on my own so my hands were pretty occupied, and half the time my girlfriend had the camera. I did try to get photos of the most important parts though to give you guys the best idea.

Ok, now on to the write-up....

CAUTION: When you remove the tcase, there is NOTHING that holds the Jeep in place. Keeping the transmission in park will not do anything because there is nothing for it to hold in place as the tcase and the drive line is gone. I highly recommend doing this on level ground, and making sure the tires are chocked. Remember, you will be lying under the vehicle for this, so if you don't chock the wheels, and the Jeep is not on level ground, it will move and potentially hurt or kill you. Don't bet your life on a parking brake!

The first thing I did was to remove the tcase skid. Then I removed my engine/trans skid. Once those were out of the way I had a complete view of the driveline.

Next I removed the linkage that connects the tcase to the shifter. I didn't want to forget to do this later, so I did it towards the top of the list.

After the removal of the skids, I removed both the front and rear driveshafts. For the front driveshaft, you will need a 5/16" wrench (or socket, if you can fit one) to remove the 4 bolts at the yoke at the axle, and the 4 bolts at the tcase output yoke.

For the rear driveshaft (in my case) you will need two sizes. For the four bolts at the axle yoke, you'll need a 5/16" wrench or socket. I found that using a 5/16" socket with a 3" extension on a 1/4" ratchet was the easiest way to do these four bolts, and then the same four bolts on the front driveshaft at the axle.

Since my busted NP242 already had the Rubicon Express HnT done on it, my driveshaft was connected to the flange with 4 grade 8 bolts. The heads on these bolts are 5/8", the nuts are also 5/8". You will need two 5/8" wrenches to remove these. First, you must remove the nuts. Once the nuts are removed you will need to remove the bolts from the flange. The flange is actually threaded also, so don't think that the bolts will just come out after the nuts are removed. This is a pretty tedious process, so take your time. It is best to unbolt the driveshaft from the axle prior to doing this so that you can raise the driveshaft up and have easier access to the four bolts.

Here is a picture of what I'm referring to:
http://i129.photobucket.com/albums/p215/dassc612/Jeep%20XJ%20Tcase%20Swap/d_shaft.jpg

Once the front and rear driveshafts are out, you will need to support the transmission because the next step is to drop the crossmember. I used a 12-ton bottle jack and a nice thick piece of wood to support the trans. You do not want to use the jack directly on the trans because you will run the risk of denting or breaking the trans pan. Place the piece of wood between the jack and the trans, then raise the jack so that the trans (and tcase) are fully supported by the jack.

Once this is done, unbolt the four nuts that hold the crossmember to the trans mount. There are four holes in the middle of your crossmember that allow you to access these nuts. If I remember correctly, you'll need a 9/16" socket for this. I also used a 3" extension to leave myself plenty of space to use the ratchet.

Once those four bolts are off, remove the two nuts and two bolts that hold the crossmember to the frame rails. I want to say that these were 15/16" but it's 12:30AM, and I'm working the overnight shift, so my mind isn't exactly on the ball.

At this point the tcase and trans are being supported ONLY by the jack, so be careful to not move the jack.

Next remove the trans mount from the trans. This needs to be removed to access the nut at the 6 o'clock position, this nut is one of the 6 that hold the tcase to the trans. The trans mount is held to the trans with two 18MM bolts. These have Blue Locktite on them, so use a breaker bar and 6-point socket to as to not round off the head. Be careful, the only thing supporting the trans and tcase at this point is the jack.

This is the transmount, and one of the two bolts that needs to be removed in order to pull the transmount off:
http://i129.photobucket.com/albums/p215/dassc612/Jeep%20XJ%20Tcase%20Swap/Oct2009-JeepXJTcaseSwap014.jpg

Once the crossmember is out of the way, you have full access to all the nuts and studs that connect the tcase to the trans. The nuts are 9/16", and I recommend using a stubby 9/16" wrench to remove these nuts. There are six nuts that need to be removed. I started with the most difficult to reach, which are the ones on the top half of the tcase. The stubby 9/16" wrench is best for these since there is minimal space. I found it best to lower the jack (slowly) to let the trans and tcase come down some to give myself more space.

This is what everything will look like without the crossmember there:
http://i129.photobucket.com/albums/p215/dassc612/Jeep%20XJ%20Tcase%20Swap/Oct2009-JeepXJTcaseSwap012.jpg

The finger on the right is pointing to the trans, and the finger on the left is pointing at the tcase:
http://i129.photobucket.com/albums/p215/dassc612/Jeep%20XJ%20Tcase%20Swap/Oct2009-JeepXJTcaseSwap008.jpg

This is the nut at the 6 o'clock position on the tcase (bottom of the tcase):
http://i129.photobucket.com/albums/p215/dassc612/Jeep%20XJ%20Tcase%20Swap/Oct2009-JeepXJTcaseSwap009.jpg

This is the nut at the 4 o'clock position on the tcase (when looking at it from rear of XJ to front of XJ):
http://i129.photobucket.com/albums/p215/dassc612/Jeep%20XJ%20Tcase%20Swap/Oct2009-JeepXJTcaseSwap010.jpg

The other nuts are found in equally tight spaces, but they were too hard to picture. Once all 6 nuts are removed, the tcase won't really move (in my experience) unless you move it. So what I did was lay on my creeper, support the tcase with both hands, and pull it straight backwards (towards the rear of the Jeep). Once the studs were out of the holes on the trans, I lowered it. The NP242 weighs about 68 pounds, so it's not too bad.

Once the tcase was out, I got to work on doing the HnT on the "new" NP242 that was going on the rig. I swapped the SYE from one tcase to the other.

Here are the two tcases side-by-side:
http://i129.photobucket.com/albums/p215/dassc612/Jeep%20XJ%20Tcase%20Swap/Oct2009-JeepXJTcaseSwap001.jpg

Here you can see the original NP242 without the SYE on it, and you'll notice how much shorter the output shaft is (the old is in the background, and the new is up closer):
http://i129.photobucket.com/albums/p215/dassc612/Jeep%20XJ%20Tcase%20Swap/Oct2009-JeepXJTcaseSwap002.jpg

Well to start the HnT process, I made sure the "new" tcase was level on the work bench, took out my 4.5" angle grinder with a cut-off wheel on it, and cut the output shaft. I taped off the output shaft so I'd know where to make the cut:
http://i129.photobucket.com/albums/p215/dassc612/Jeep%20XJ%20Tcase%20Swap/Oct2009-JeepXJTcaseSwap004.jpg

Cut:
http://i129.photobucket.com/albums/p215/dassc612/Jeep%20XJ%20Tcase%20Swap/Oct2009-JeepXJTcaseSwap005.jpg

After cutting, I hit the output shaft with a flap disc to make sure it was nice and square. My original cut was pretty good, so it just need a minor touch up. Then I took a file and cleaned up the splines a bit near where I made the cut so that the SYE would slide right on... like a glove:
http://i129.photobucket.com/albums/p215/dassc612/Jeep%20XJ%20Tcase%20Swap/Oct2009-JeepXJTcaseSwap007.jpg

http://i129.photobucket.com/albums/p215/dassc612/Jeep%20XJ%20Tcase%20Swap/Oct2009-JeepXJTcaseSwap006.jpg

I then took a punch and marked where I'd be drilling the hole, that I'd then tap for the bolt that holds the SYE to the output shaft.

Take your time when drilling the hole, and make sure that you use a good set of drill bits. The hole has to be nice and square, and straight. The hole has to be 21/64" in order to use a 3/8" tap. My best advice is to start with a small drill bit and work your way up in increments, finishing with the size that you need. This is how I was taught to drill, and it works well.

You need to drill the hole about 1" deep into the output shaft. Once it's drilled, use a 3/8" tap and tap the full length of the hole. Take your time with this as well. Use plenty of WD-40 or oil to keep the process smooth.

Once the hole is tapped, slide the SYE back on, and torque it. I also used some Blue Locktite on the bolt.

Now the tcase is ready for install. Install is essentially the direct opposite of how you removed the tcase. Line the studes back up with the holes on the trans, slide the tcase on (the splines on the tcase and trans will move enough so that that they engage properly). Once the tcase is on, put the 6 nuts back on the studs.

Then remount the trans mount to the trans. Followed by the crossmember. Once the cross member is mounted to the trans, raise the jack back up, and bolt the crossmember to the framerails.

Once the tcase is mounted up and the crossmember is mounted to the framerails you can remove the jack supporting the trans.

At this point, make sure you fill the tcase with fluid. It takes about 1.5 quarts or so of ATF.

The top hole is the fill plug, and the bottom is the drain plug:
http://i129.photobucket.com/albums/p215/dassc612/Jeep%20XJ%20Tcase%20Swap/Oct2009-JeepXJTcaseSwap016.jpg

Once you fill the tcase, reconnect the linkage, and then the driveshafts. Take it for a spin, shift through the tcase and make sure it's working properly.

COSXJFAN
10-13-2009, 08:51 AM
Nice write up Dave!!

Mudderoy
10-13-2009, 10:10 AM
Yes very nice, thank you. I don't care how many people there are that have done this 15,000 times, there are those of us (ME!) that haven't and spend lots of time looking for good "HOW TO's" before I tackle the job. :patriot:

2000XJ
10-13-2009, 08:53 PM
Thanks guys! My intention was to make the write-up easy enough for anyone to use. One thing that I ran into alot when I first got into this sport was the lack of good, newby-friendly write-ups, so now I'm just trying to pay it forward. I have honestly dropped the tcase on my friend's TJ probably 5 or 6 times this summer, so this was really just a really simple job. I hope the write-up helps out those who are first-timers because that is the intention.

Mudd - I love the "pop up" windows that you made for some of the abbreviations throughout the right-up!

xj4lifetwo
10-15-2009, 10:55 AM
Nice write up !! great job on the saftey tips , so many people get hurt not paying attention

xj4lifetwo
10-15-2009, 10:59 AM
This should be moved up and stickied I think Thanks again

4.3LXJ
10-15-2009, 11:03 AM
Yes, stickied is a good idea. Nice write :congrats:up

2000XJ
10-15-2009, 08:44 PM
Woohoo!! It got stickied! Thanks alot for the positive words guys! If you guys know of a better way of doing something, or a different approach to something regarding the swap or the SYE, please post it up, I won't get insulted!

Mudderoy
10-16-2009, 03:07 AM
Woohoo!! It got stickied! Thanks alot for the positive words guys! If you guys know of a better way of doing something, or a different approach to something regarding the swap or the SYE, please post it up, I won't get insulted!

I think having the thead copied to "Articles" was a bigger deal but if you like it sticky who am I to judge. :shocker:

BlueXJ
10-17-2009, 02:50 PM
I did mine with the t-case still in the Jeep. I also used the engine to run the t-case output shaft while cutting to make sure I got a square cut. Great write-up anyway. I have had mine out on the bench for rebuilds but never considered it for the HnT.

2000XJ
10-19-2009, 06:05 PM
I did mine with the t-case still in the Jeep. I also used the engine to run the t-case output shaft while cutting to make sure I got a square cut. Great write-up anyway. I have had mine out on the bench for rebuilds but never considered it for the HnT.

The first time I did the HnT on the original tcase, I did it with the tcase on the XJ as well. It was super convenient, especially because I was using my friend's lift. This time around, it was more convenient on the bench. I would've prefered to have done it with it on the XJ again, but hey, live and learn.

BlueXJ
10-19-2009, 07:13 PM
Yeah I used a lift too when I cut mine. You did a great job. My hand would not have been steady enough to get such a nice square cut like you did. Congratulations!!!

2000XJ
10-20-2009, 12:52 PM
Thanks! I was super paranoid about it, you know how you only get one chance with cuts like that. If I had messed that up I would've looked like this: :smiley-scared002:

alwaysxj
10-20-2009, 04:53 PM
nice write up. i need to do this so bad to my jeep some time in the near i will do it. (if the wife will let me have the money)

2000XJ
11-28-2009, 10:17 PM
Thanks! Keep your eyes open on Craigslist, your local JY's, and ebay. There are good deals to be had out there for tcases.

4.3LXJ
11-29-2009, 11:01 AM
Thanks! Keep your eyes open on Craigslist, your local JY's, and ebay. There are good deals to be had out there for tcases.

I have a Np231 with both input gears someone can have for free if they will pay shipping