Transfer Case Swap Info NP249->NP231 & NP242 - Page 17 - JeepForum.com
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Unread 01-20-2011, 10:33 AM   #241
jlipka98zj
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Straight from post #1 on this thread (you should be ashamed, lol):

Quote:
There are 3 different input shafts, .750", .840", and 1.55", as well as both 21 and 23 spline shafts. All ZJ transfer cases have a 23 spline input shaft, and all 92-01 XJ's have a 23 spline input shaft. 91 and older XJ's have the 21 spline input.

Your best bet is to find a transfer case with the same input shaft. If not, you can swap input shafts, but be aware of the annulus gear cut change that occurred in mid 94.

It's best to go by the build date on the transfer case, not the year of the Jeep when determining the gear pitch. Rule of thumb is cases with a build date of pre 94.5 will have the old style gear cut, and cases with a build date of post 94.5 will have the new style gear cut.

My personal experience is that a 249 with a build date of 3/94 still used the old style gear cut.

If you're swapping a 242, you can do what is referred to as a front case swap if you're in a bind with two different gear cuts (no pun intended.) The 242 and 249 both share the same front case half, meaning you use all the parts from the 242, with the exception of the 249 input, 249 planetary set, and 249 front case half.
Read further on down in that post for instructions on how to actually do it. I highlighted a few tidbits that are pertinent to your individual case.

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Unread 01-20-2011, 10:36 AM   #242
squazz
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some one was telling me that in th 4.0L I6 you dont have to worry about gear cut
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Unread 01-20-2011, 10:41 AM   #243
jlipka98zj
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Quote:
Originally Posted by squazz View Post
some one was telling me that in th 4.0L I6 you dont have to worry about gear cut
He didn't specify engine types on either the donor or recipient vehicles. And it's actually somewhat irrelevant.

Because pre-92 XJ's have a 21-spline input and his ZJ has a 23-spline, he is going to have to change input gears AT A MINIMUM. Once he pulls the input out, he can check and make sure the gear cut is the same and proceed with putting the 249 input in the 242 planetary.

Or, verifying the correct gear cut can be avoided altogether by transplanting the entire planetary assembly from the 249 into the XJ 242. That process is outlined in its entirety in post #1 of this thread, as well as countless other sources on the internet.

If you go to the tech section of the Kevin's Offroad site, he has links to three separate 249 to 242 swaps for Grand Cherokee's.

I just got lucky in that the case I got my hands on was a direct bolt-in swap for mine.
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Unread 01-20-2011, 11:23 AM   #244
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Quote:
Originally Posted by jlipka98zj View Post
He didn't specify engine types on either the donor or recipient vehicles. And it's actually somewhat irrelevant.

Because pre-92 XJ's have a 21-spline input and his ZJ has a 23-spline, he is going to have to change input gears AT A MINIMUM. Once he pulls the input out, he can check and make sure the gear cut is the same and proceed with putting the 249 input in the 242 planetary.

Or, verifying the correct gear cut can be avoided altogether by transplanting the entire planetary assembly from the 249 into the XJ 242. That process is outlined in its entirety in post #1 of this thread, as well as countless other sources on the internet.

If you go to the tech section of the Kevin's Offroad site, he has links to three separate 249 to 242 swaps for Grand Cherokee's.

I just got lucky in that the case I got my hands on was a direct bolt-in swap for mine.
This is correct, EXCEPT that it's not as simple as just using the 242 planetary if the gear cuts are different. Part of a planetary gear unit is the annulus gear. Obviously the sun gear (input shaft), planetaries, and annulus all have to mesh together to function, so while the sun gear and planetary gears would mesh, the assembly would bind up inside the case.

I have heard of guys pulling the annulus gear out of the front half of the case and swapping them, but I've never done it nor would I attempt it if I were the average guy doing this out of his garage.
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Unread 01-20-2011, 11:52 AM   #245
jlipka98zj
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Quote:
Originally Posted by JrMechanic View Post
This is correct, EXCEPT that it's not as simple as just using the 242 planetary if the gear cuts are different. Part of a planetary gear unit is the annulus gear. Obviously the sun gear (input shaft), planetaries, and annulus all have to mesh together to function, so while the sun gear and planetary gears would mesh, the assembly would bind up inside the case.

I have heard of guys pulling the annulus gear out of the front half of the case and swapping them, but I've never done it nor would I attempt it if I were the average guy doing this out of his garage.
Forgot about the annulus gear. So is this a case where you would want to do a full front case half swap?
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Unread 01-20-2011, 05:29 PM   #246
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Its so much easier to just find a case out of the proper year vehicle than try and take both apart and make one that works out of them. Just look for the right case and spend 2-3 hours doing the swap and be done with it. It really is as simple as that.
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Unread 01-20-2011, 05:39 PM   #247
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Quote:
Originally Posted by PlatinumNiner View Post
Ther only year ZJ that came with the 231 option was 1993 as far as i know. You are right the XJ can use anything it has no VIC.
The 231 was available from 93-95.

As far as the '89 XJ case into a '96 ZJ, it is doable with the 249 front case half. Depending on the Jeep it's going in, this may be worth it to retain the internal slip yoke.

I already prefer the ISY to the ESY, but the ISY is better for lifted rigs as it adds about 1.5" of rear drive shaft length over the ESY. The farther the rear output is from the rear differential the lesser the chance of drive line vibes when lifted and the easier it is to dial in the pinion angle.
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Unread 01-20-2011, 06:42 PM   #248
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Your right it was the AW4 that was only an option on the 93 ZJ
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Unread 01-21-2011, 07:37 AM   #249
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I have a 95 ZJ the transfer case has a date of 2-10-95. I have located a 231 transfer case with a date of 8-94 out of a 95 ZJ. Will this have the same gear cut?

Also i have a cv front drive shaft. Will a 95 U-Joint drive shaft bolt right in?
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Unread 01-21-2011, 11:56 AM   #250
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Quote:
Originally Posted by JeepZJ95 View Post
I have a 95 ZJ the transfer case has a date of 2-10-95. I have located a 231 transfer case with a date of 8-94 out of a 95 ZJ. Will this have the same gear cut?

Also i have a cv front drive shaft. Will a 95 U-Joint drive shaft bolt right in?
The cuts should be the same, but 8/94 is really iffy. According to my experience and research, that should be after New Process retooled, but stranger things have happened.

You will need a 1310 U joint yoke from a Dana 30 to replace the CV yoke on your front axle. Tread lightly, swapping yokes isn't as easy as you would think (in the long run, that is).
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Unread 01-21-2011, 12:30 PM   #251
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What do you mean by "in the long run"?. Would i be better off getting the whole front end from a u-joint style truck rather than changing my existing yoke? I'm going to be adding a 3.5" lift and i've heard to ditch the cv style.
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Unread 01-21-2011, 06:16 PM   #252
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Quote:
Originally Posted by JeepZJ95 View Post
What do you mean by "in the long run"?. Would i be better off getting the whole front end from a u-joint style truck rather than changing my existing yoke? I'm going to be adding a 3.5" lift and i've heard to ditch the cv style.
He means long run because it will probably work for a few miles, but eventually your pinion bearing will take a dump.

If you are going to swap an entire u joint style front end, get an HP dana 30 out of an XJ. Otherwise it isnt worth the effort

The rezeppa or CV style front driveshaft my jeep came with lasted about 3 months after i lifted 3.5". I replaced it with the u joint style and havent had problems since
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Unread 01-22-2011, 09:32 AM   #253
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Just to share and show the difference of a 93-95 242 transfer case and a 96-98 242

93-95



96-98




96-98 on left 93-95 on right

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Unread 01-22-2011, 05:56 PM   #254
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Do yourself a favor if your going from a 249 on a 96-98 zj to a 242 case from a 96-98 zj and maybe some othgers, cut 1" off the yoke on the driveshaft. The 242 case is longer and you only have about 1/2 of play before you bottom out if you dont cut the yoke. If you are lifted i wouldnt worry but if your stock it's very close.
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Unread 01-22-2011, 08:22 PM   #255
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'93 242 swap into a

Fantasitc thread. Just spent the last hour reading it. This may be in the all the replies already so sorry if this has been asked already. I have a '97 Grand Cherokee with the I6 engine, 42re tranny and 249 transfer case. The VC has gone bad. I found a 93' Grand Cherokee in the wrecking yard today with the I6, (not sure what auto tranny, looks different than mine) and a 242 transfer case. Both transfer cases are external slip yokes. I read all about the different input shaft lenghts, gear cuts changing in '94, etc... Will the '93 242 be a direct swap for my '97 249? I'm wondering will the input shafts be the same length since they are both 6 cylinder engines and in Grand Cheerokees? If not, can I use the front half of the 249 on the 242 since changing the input shaft will not work (different cuts in the gears).

Last edited by Grandplans; 01-23-2011 at 07:51 AM.. Reason: clarified a couple of things. last sentence
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