Can a 96-98 'Lo Lock' 249 transfer case go in a 94? - JeepForum.com
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post #1 of 25 Old 08-07-2020, 02:27 PM Thread Starter
speedbrake
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Can a 96-98 'Lo Lock' 249 transfer case go in a 94?

First: I’ve read JrMechanic’s stickied write up on the 249 to 231/242 swap. A million views, pretty impressive. Probably 100+ of those views are mine, since I read the whole thing. Learned a lot. Second: I’m aware of potential VC problems with the 249. I own two 249s, one with 265K and one with 140K. Both VC’s still working! Third: I like the 249. Yeah, it’s big and heavy. But it works for me with the high % of street driving I do, and it’s fantastic in Denver snow. So please, thanks in advance for skipping the “swap in a 242” replies. That said, my question is: Is it possible to put a 96-98 249 transfer case (one with Lo Lock) in place of my ’94 249 transfer case? Details: My ’94 has the V8, 46RH transmission, and the “old” (pre-May ’94) gear cut in its current 249 case. JrMechanic tells us that 93-95 V8 ZJs with 46RH tranny have a 1.55” 23 spline input shaft. And 96-98 ZJs have an .840” 23 spline input shaft. Apparently, all ZJ transfer cases have a 23 spline input shaft. But the spline # isn’t the problem. Will my 46RH play nice with the .840 input shaft instead of the 1.55” input shaft? It seems like it wouldn't work since there’s a 0.71” difference in input shaft length. Measured my spare 249 and it shows that the 46RH trans output double lip seal wear marks are 11/16” (0.6875”) down the shaft. If I’m picturing this correctly in my head, a .840 input shaft would engage the tranny output shaft 0.71” less than it currently does. Plus, the tranny output seal would be approx at the end of the .840 shaft and thus not sealing very well, if at all. So please weigh in with opinions/experience. And if a direct swap won’t work, is there a workaround?

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post #2 of 25 Old 08-07-2020, 02:31 PM
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You really want to use the 1.55" input shaft with the 46rh or you'll have seal issues.

That said it's reasonably easy to do an input or front case swap on a second gen 249 to get the low lock and different power distribution.


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post #3 of 25 Old 08-07-2020, 02:56 PM Thread Starter
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So I could swap in a 1.55" input shaft into the second gen 249, but it would have to be from a post 5/94 (or so) thru 95 249? I couldn't do it with the 1.55" input shafts I have now bc they're old gear cut, right?
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post #4 of 25 Old 08-07-2020, 03:52 PM
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Correct, with the gear cuts you have you'd need to use the front case half of the first gen 249 and back case and guts of the second gen.


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post #5 of 25 Old 08-07-2020, 04:40 PM Thread Starter
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Could I use the front case half of my current 94 249 (old gear cut) with the back case and guts of a second gen 96-98 249? Or would the front half in that swap HAVE TO be from a "new gear cut" 249? New gear cut meaning Mid 94 thru end of 95s (with, of course, a 1.55" input bearing).
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post #6 of 25 Old 08-07-2020, 04:56 PM
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The gear cut difference is in the planetary, which interfaces with the front of the case. So you'd be using your current front case and planetary, and second gen everything else.


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post #7 of 25 Old 08-07-2020, 06:38 PM Thread Starter
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Ok. That's outstanding! Thought I was going to have to find a front case from a 95 with the new gear cut. But if I understand you correctly, I can use my current front case and planetary mated to a rear case from the '97 249 and also the mainshaft/guts/etc from the '97 249. That about right?
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post #8 of 25 Old 08-07-2020, 07:26 PM
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As kg6mov mentioned, if you have the different gear cut you use the front case half + input gear + front planetary from your current vehicle, and everything else from the donor TC.
I installed a 1990 242 into my 1998 5.9 using the front case half + planetary + input gear (and electric speed sensor) from my 1998 249, and everything else from the 1990 242.

1998 Grand Cherokee 5.9 LX daily driver, 1.75" BB, 32" KM2s, HPD30 Eaton e-locker/D44a stock LSD, 4.56 gears, custom- fabbed tube bumpers and tube fenders,...


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1990 XJ Limited (4-door), 4.0 I6, AW4, NP242, ***rolled and totalled @ 165k miles***

***Under construction***
1990 XJ (4-door), 4.0 I6, AW4, NP242, PBR 42" tires, Unimog 404 portal axles, 110" WB, full cage + uniframe completely rebuilt, front 3-link + panhard / double triangulated 4-link rear,... ***SOLD***
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post #9 of 25 Old 08-07-2020, 08:02 PM Thread Starter
speedbrake
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Excellent! Thank you, gentlemen. Appreciate the help. Swap sounds straightforward, now that I know exactly which parts to use. Any other gotchas, quirks or 'oh, by the ways' I should be aware of for this swap?
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post #10 of 25 Old 08-07-2020, 08:39 PM
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Quote:
Originally Posted by speedbrake View Post
Excellent! Thank you, gentlemen. Appreciate the help. Swap sounds straightforward, now that I know exactly which parts to use. Any other gotchas, quirks or 'oh, by the ways' I should be aware of for this swap?
Just so you know, 93-95 249 react faster when slippage occurs. There is a slight delay with the 96-98 249 but it's predictable and you gain low lock and can remove the front shaft without any problems.

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post #11 of 25 Old 08-08-2020, 04:17 AM
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I actually preferred the feel of the newer 249 due to it being about 10/90 front/ rear biased before wheelslip occurs so it normally handles like you're driving an RWD.
If you get wheelslip in snow/ ice, it doesn't take long at all for the front to catch up, but you do get the rear to kick out a bit so you're actually turning on slippery corners, not going straight into a ditch.

As PolkaPower mentioned, the way the newer 249 acts is very predictable and easy to drive. I've tested a few older 5.2 ZJs with the first-gen 249 and didn't like how they handled on snowy/ icy roads.

1998 Grand Cherokee 5.9 LX daily driver, 1.75" BB, 32" KM2s, HPD30 Eaton e-locker/D44a stock LSD, 4.56 gears, custom- fabbed tube bumpers and tube fenders,...


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1990 XJ Limited (4-door), 4.0 I6, AW4, NP242, ***rolled and totalled @ 165k miles***

***Under construction***
1990 XJ (4-door), 4.0 I6, AW4, NP242, PBR 42" tires, Unimog 404 portal axles, 110" WB, full cage + uniframe completely rebuilt, front 3-link + panhard / double triangulated 4-link rear,... ***SOLD***
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post #12 of 25 Old 08-11-2020, 05:56 AM
Zilliver
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Im the guy who likes the ´93-95 feeling

If my ´98 249 fails, it will get the older style, its already waiting in the garage
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post #13 of 25 Old 08-12-2020, 05:15 PM
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Ive honestly never been able to tell a difference between my 5.9 and 94 4.0.

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post #14 of 25 Old 08-13-2020, 12:33 AM
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Ive honestly never been able to tell a difference between my 5.9 and 94 4.0.
IMO it's very noticeable on snow and ice, not so much in the rain, pavement or dirt roads.
When wheeling, I've witnessed multiple cases where a ZJ with the older 249 has been stuck due to lack of lo-lock, where 242/231/ newer-249- equipped have had no problems going through the same spot.

1998 Grand Cherokee 5.9 LX daily driver, 1.75" BB, 32" KM2s, HPD30 Eaton e-locker/D44a stock LSD, 4.56 gears, custom- fabbed tube bumpers and tube fenders,...


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1990 XJ Limited (4-door), 4.0 I6, AW4, NP242, ***rolled and totalled @ 165k miles***

***Under construction***
1990 XJ (4-door), 4.0 I6, AW4, NP242, PBR 42" tires, Unimog 404 portal axles, 110" WB, full cage + uniframe completely rebuilt, front 3-link + panhard / double triangulated 4-link rear,... ***SOLD***
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post #15 of 25 Old 08-19-2020, 10:09 PM Thread Starter
speedbrake
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Got the donor tcase with Lo Lock. May '97 build date. Crusty, but otherwise good shape. $50. Just out of curiosity, what's that V-shaped bracket secured by the bolt on the pax side of the rear extension housing? I don't have that on my '94. Also, I'll be replacing seals when I do the front case swap. I have all the seal part #s for my 94, but does the 97 use the same seal #s?
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