Any NP242 transfer case experts out there?

[schardein]

I picked this 242 out of a 1991 XJ.  Got to looking at the driver side near the linkage and there is a hole.  Not sure what it is for.  Indicated by the blue arrow in the photo.  Anyone know what that hole is for?

 

[PIKE]

There is  a small rubber plug that goes in there. You should be able to get one from a Dealer. Part # 00015105

 

http://www.moparpartsoverstock.com/p/JEEP_1991_CHEROKEE40L-I6-Power-Tech--5-Speed-Manual/PLUG-Transmission-Case-PLUG--PLUG--Oil-Access-Hole--Rt-Side-Rubber--PLUG--Rear-Case-52098899--52111083--From-91002--Thru-9902--With-Police--Without-Po/6637496/00015105.html

[schardein]

OK thanks.  

 

So, do you happen to know if 231 t-case has that also?  Guess I'll look under my XJ... if so I will source one from the junkyard.

 

Do you know if it is some sort of inspection port?

[cruiser54]

What year trans are you planning on using with it? 

[schardein]

I got it to eventually use in either my 91 Xj or the MJ as part of a 4wd conversion.    I've rebuilt Dana 300, Dana 20, Dana 18, NP203, and NP205 cases, but never messed with a 231/242.  So I plan to tear this one down just to become familiar with it.  I've been on the lookout for a 23 spline version for a while.  This one was still attached to the transmission and sitting in the back of the XJ, in other words already pulled out.  I took that as a sign and was in and out with it in 30 minutes.

[schardein]

I guess to better answer your question, whatever year transmission it is compatible with, and is also compatible with my 91 MJ as part of a 4wd conversion.  Do you know what years AW4 would be compatible with a 1991 MJ for a 4wd conversion?

 

The transmission was also in the junkyard XJ, but the snout of the torque converter was damaged and the truck had over 300,000 miles on it.  I plan on going through the transfer case anyway, but for a transmission, I'd rather find a known good used one.

[Doc.]

"Any NP242 transfer case experts out there?"

I'm no expert, but I know they're not very good. Most people take them out when they go bad a put in a 231.

[Rockfrog]

The 242 is a fine transfer case, If you have been through a gear driven case as you mentioned the 242 is child's play.

Generally 242's don't go bad anymore than a 231 does, and usually for the same reasons ... Poor maintenance/low fluid.

It has no weird gimmickery inside, it is a simple geared differential inside to allow for the full-time 4wd range.

They do tend to be a little finicky when shifting though but that's about the only real negative.

They are stronger in some aspects than the 231 (chain and front outputs), and equal in others.

[oldseddie]

I don't get on here as often but I have a lot of experience with them. I have one in my son's 91 mj and my 87/97 project mj. Mine is behind an ax15. Both are 97 or newer as they are much improved units over the earlier ones. Gotta keep a tight chain if you put one behind an ax15.

[schardein]

"Any NP242 transfer case experts out there?"

I'm no expert, but I know they're not very good. Most people take them out when they go bad a put in a 231.

I've had an XJ with a 242 before, but never did hardcore off road with it.  If it does go bad, I suspect 231s are a good choice as a replacement simply because they are easier to find. 

 

 

The 242 is a fine transfer case, If you have been through a gear driven case as you mentioned the 242 is child's play.

Generally 242's don't go bad anymore than a 231 does, and usually for the same reasons ... Poor maintenance/low fluid.

It has no weird gimmickery inside, it is a simple geared differential inside to allow for the full-time 4wd range.

They do tend to be a little finicky when shifting though but that's about the only real negative.

They are stronger in some aspects than the 231 (chain and front outputs), and equal in others.

I thought 242s had a viscous coupling?

 

 

I don't get on here as often but I have a lot of experience with them. I have one in my son's 91 mj and my 87/97 project mj. Mine is behind an ax15. Both are 97 or newer as they are much improved units over the earlier ones. Gotta keep a tight chain if you put one behind an ax15.

Can you elaborate on what the differences are on the later model 242s?

[Rockfrog]

The 249 has a viscous coupling, the 242 is a simple mechanical differential.

[oldseddie]

The 97+ shift in and out of all positions whereas the older ones can get stuck in 4 high and requires some forward and reverse technique to get it unstuck. Some of the later ones had a six spur gear which is stronger. There are some differences in input shaft spline count from 89- and shaft length but the 98 fit my sons original aw4. and the 99 fit my late ax15 with no problems.

[Rockfrog]

They follow the same pattern as the 231, pre 91 and 4cyl had 21 spline inputs, 91+ 6cyl were all 23 spline. The often talked about medium input was primarily in the early 21 spline cases, and the ZJ V8vs had the long spline inputs. Most XJ's were all the same length.

Around 97 they 23* series and 24* (and I suspect most NP/NVG 'cases) were changed internally, the main shaft needle bearings were eliminated in favour of an oil film bearing, and the internal brass synchro was changed and made a stationary guide as a part of the main shaft. The reason early 231/242's hung so bad was simple synchro wear.

The 242 shares many parts with the 231, such as the entire input and planetary assemblies.

[schardein]

Thanks to everyone for the good info.  I'm looking forward to digging into this thing and seeing what's what.  Not sure when I'll get to it, as I have some projects in front of it.  5.3 engine swap in the -7, ground up resto/build on the -5, rusty brake line replacement on the Silverado.  So many projects so little time.

[mikekaz1]

"Any NP242 transfer case experts out there?"

I'm no expert, but I know they're not very good. Most people take them out when they go bad a put in a 231.

 this is false...   if you look up new processes id chart the second character is strength, thus a 242 is technically stronger then a 231. I think most people replace them with a 231 just because of availibility

[mikekaz1]

to buddy this question,   the 231 cases differ in that the early ones (with vacuum disconnect) don't have a true neutral.  is this also true with the 242? and did they use a vacuum disconnect or did they have full solid shafts?

[Minuit]

No idea on your first question, but I'm pretty sure the 242 was always paired with solid axle shafts.

[schardein]

I once owned a 1989 XJ Wagonner with the woodgrain and 4 headlight grill.  It had the 242 and the front Dana 30 was a non-disconnect.  In my search for a 242, I've seen several pre-91 at the junkyards, but wanted to hold out for a 23 spline application.  All the pre-91 I have seen used a non-disconnect front axle.

[Doc.]

All I can say is that's interesting. I've replaced several 242's that went bad for guys and never a 231. We've always put a 231 in because of availability and their research says the 231 is stronger. Guess I've been misinformed. Sorry.

[oldseddie]

I think the reason that the 242 boxes get such a bad rap is that those of us that have them use them all the time, whereas the part time boxes only get used when it is slick everywhere. My Comanche handles better in curves and is safer in the rain.

[mikekaz1]

I really want to convert to a 242. I have the earlier 21 spline input. And trying to find other case differences between type sets. On if I should try and find a 21 spline or convert a 23 spline to 21.

[mikekaz1]

http://www.socalultimate4x4.com/index.php?topic=4786.0

 

Here's a NP numeric breakdown list

[schardein]

 

I think the reason that the 242 boxes get such a bad rap is that those of us that have them use them all the time, whereas the part time boxes only get used when it is slick everywhere. My Comanche handles better in curves and is safer in the rain.

I have a curvy 25 mile one way drive to work every day.  This would be a plus for me.

 

 

http://www.socalultimate4x4.com/index.php?topic=4786.0

 

Here's a NP numeric breakdown list

 

Interesting info.

 

I bought my MJ with intentions of converting it to 4wd.  Since buying it I have had second thoughts of just enjoying it the way it is.  If I do convert it, I figure I might as well use a 242, my previous experience with them is that they are perfect for winter driving with patchy ice and snow on the roads.

 

[oldseddie]

I have an early 242j with 21 spline input. Too bad you are so far north as I would let it go for $100.

[gogmorgo]

I think the reason that the 242 boxes get such a bad rap is that those of us that have them use them all the time, whereas the part time boxes only get used when it is slick everywhere. My Comanche handles better in curves and is safer in the rain.

That. All of it. On a gravel road I can carry 10-15% more speed through the corners and get back on the power much earlier in full-time than in part-time.

I also use the 4x4 much more than I did with the 231. Higher failure rates due to greater component wear wouldn't surprise me at all. I'd say 80% of the last 1500 miles has been in full-time, whereas with the 231 I might have been in 4x4 for maybe 5-10% of that. I drive most of the same places for work as I do on my own time and hardly ever touch the 4x4 lever in my work truck which only has part-time, but my MJ is in full-time everywhere except the highway.