The transfer case on my 87 Jeep Cherokee
http://www.hobbyguild.com/jeep I tried to locate a replacement Selectrack NP-242 transfer
case, but could not find one locally, and did not want to part with 800 bucks,
so I decided to try a swap to a NP-231 Commandtrak which I know I could get used
for $150.00
Some details:
The NP-242 is full time 4WD with the
following ranges
2W High
4W High Differentiated
N
4W High Lock
4W
Low Lock
The NP-231 is a part time 4WD unit with the following
ranges:
2W High
4W High Locked
N
4W Low Locked
The NP-242 failed
because the oil tube coming from the pickup sump to the pump fell out and got
into the chain. With out lubrication, it burned itself up.
I will post some
autopsy pictures when I get around to it.
The NP-231 has a different
input spline than the NP-242, so I needed to swap the original input shaft from
the old 242 into the 231.
Also the front output had a different yoke on
it, I am currently running with only a rear drive shaft, I will take the yoke
and front shaft to my local drive shaft shop and have him fix it. The rear drive
shaft fit no problem.
Linkage: The shift pattern is different
(Obviously), but I didn't expect it to be reversed. Yep when running in 2WD the
selector lever in the cab needs to be in the up (pulled back and up) position.
All the way forward is 4WD Low Lock. I'm sure I could correct this minor glitch
if I felt like it, Maybe somday I will.
First you split the case open
This image shows what a pump, pickup tube and sump screen should
look like.
This is the inside of the front half. On the right side is the
planetary assembly that contains the input shaft. You need to remove it to get
to the shaft.
This shows the two different planetary assemblys, on the left is
the original NP-242 input and on the right is the one that came with the
NP-231.
The inputs have a different number of splines too. The 242 had a 21
count spline, the 231 had a 23 spline.
Close up of the input coupler after being removed from the
planetary gears.
This is the input side of the NP-231 with the NP-242 input shaft
installed in it.
And the output side just for reference. (The tail shaft covers
are not installed.)
If you liked this page, or it helped you out, I'd
like to know. E-mail me below.