SeriousOffroad

I spent the better part of today on the transfer case. Even though I had previously installed a 4 planetary low range from the Chevy NP231, I really wanted the increased strength of a 6 planetary. I could have scrounged around the junk yard for donor 231HD od a 241HD, I really wasn't to thrilled about the idea of tearing a t-case apart in the JY just for the low range. After getting some info from Pirate4x4 (http://www.pirate4x4.com/forum/showthread.php?t=854320) I opted to build my own use the parts I had on hand. I also received my JB Conversions NP231C Short Shaft SYE on Friday so the timing was right to do them both. A little walk-thru for those that might be interested...

Remove the t-case from the rig and find a spot to work on it.


Remove the tail shaft housing.


Note the difference in the VSS location. Jeep tail cone is in the foreground.


The VSS needs to come out in order to get to the bolt hidden behind it.




After removing the tail cone you'll find the 40 tooth reluctor ring for the VSS. Use a good quality set of snap-ring pliers to remove the lock-rings and slide the reluctor off.






Remove the oil pump making sure you don't lose the o-ring for the pick-up tube.


Remove all of the bolts holding the front and rear halves of the t-case together and then separate using a putty knife. This is a good time to pull the oil-screen and magnet for a thorough cleaning. Since my -t-case hasn't even had fluid in it yet I didn't need to do that.





Remove the front output shaft yoke.


Now the main shaft, chain, and front output can be removed.


Remove the mode fork, range fork, and the rail.


Remove the bolts holding the forward seal housing in place and pry the housing up.

SeriousOffroad

Remove the snap-ring that retains the input shaft. Carefull! The input shaft and low range gear will fallout as soon as the snap-ring is removed.


Remove the large lock-ring in the low range housing in order to remove the input shaft.


At this point I had to use the pin and planetary gear as a makeshift jig so I could reinstall the two rows of needle bearings in the planetary. The two rows are seperated by a small washer.


After installing the planetary gears into the low range housing, use a cold chisel to stake the pins in place. Now you've got your own homebrew booty fab 6 planetary low range gear!



Comparison pic of the OEM Chevy 32 spline main shaft and the JB Conversions short main shaft.


Remove the snap ring that retains the drive sprocket and the mode hub. Slip them off the the old shaft and onto the new short shaft.


Reinstall the input shaft into the lowrange, and then install those into the forward case half followed by the snap ring.


Re-install the mode fork, range fork, and the rail, followed by the front output shaft, chain and main shaft.






Re-install the magnet.


Don't forget that the oil pump goes on the outside of the rear half.


Hopefully you've been using a brass wire wheel in a drill to clean all of the mating surfaces. DO NOT USE STEEL WIRE WHEEL!!
Once your surfaces are clean it's time to add a little gasket maker. I strongly recommend.....


Re-assemble the two case halves.

SeriousOffroad

Install a snap-ring once the oilpump is in the proper position.


Now install the reluctor ring and the second snap-ring.



The JB kit comes with a new sealed bearing the replaces the OEM bearing in the outputshaft housing. Drive the old bearing out from the inside toward the outside.

The new bearing is easy to install but it must be installed with the protruding inner race towards the inside of the case.






The new bearing will protrude from the tailcone after it's driven all the way in.


Apply a liberal coat of grease to the new seal and then install the new seal housing onto the tail cone.


Install the new rubber gasket on the mainshaft, followed by yhr new yoke.


Finally, I re-installed my clocking ring onto the case and then re-installed the case in my heep.

mobilecherokee4

great thread man, thats pretty intense

Ritter4.0

Thanks, awsome right up! Now I can add this to my list of to do.......

nhegel

So this does not change ratio, just adds strength?

SeriousOffroad

Correct.

trans_am7935

is there anyway besides ripping your transfercas apart if you have a 6 hole or 3 hole in your transfer case? i am gonna put my SYE kit from JB on next week and saw this thread. looks like a good idea. can you buy extra planetary gears new or only get them used?

SeriousOffroad

AFAIK, Jeep low range gears have 3 holes. The 6 hole low range (4 planetary) came out of a mid 90's Chevy Blaver (S10/S15).

As far as ordering/buying additional planetary gears is concerned, highly unlikely. But then again you might find a driveline shop that can order them for you, or you could ask your local Jeep dealer.

ki4dmh

Awesome info!!! Thanks!

zedpapa

would a 241C transfer case work as a donor? i would like to do this to my 242J while i am rebuilding it.

zedpapa

SeriousOffroad

Yes, 242c and j parts are also interchangeble.

4.3L XJ

Nice job Frank