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NP 242 options for the Newbie

R

RedFive

NAXJA Forum User
Location
San Jose, CA
Veteran XJers,

I bought an 87 Limited off of my brother over a year ago. The vehicle has an automatic tranny mated to an NP242. It's my daily driver and will never be intended for hard wheeling. It has about 5.75" of lift on it (4" springs and polyurethane spacers)...

...and of course, the driveshaft vibrates at highway speeds.

I've searched the forums and it appears that there are not a lot of options for the 242...I can either HnT it, or I can fab up my own slip yoke from a Corvette/Hummer/GM version of the yoke. I'm not a fan of the HnT kits, and I don't have the means to fab up my own custom yoke, plus I don't really need an HD SYE setup as the Jeep is just used to get to work, get up to Lake Tahoe, carry my Mtn. Bike. So...

...it seems obvious to me, but since the drive shaft is too short, the slip yoke has slipped out a bit, and the U-joint is binding/vibrating at highway speeds, couldn't I just take my Rig down to the local driveline shop, have a CV-joint put in place of the U-joint, and have the drive shaft lengthened so that the slip yoke is back in it's original position (see picture) ?


352a.jpg


Is the solution this obviouis, or am I completely missing something?

Tony in San Jose
 
cal said:
http://www.4xshaft.com/double_cardan.html

"This type of conversion is not recommended for the New Process 231 or 242 transfer case. In these application we suggest one of the tail shaft conversions."

I'm sure there is a good reason for it.
Click to expand...

But what would that reason be? That Tom Woods wants to sell his setup? Again, I don't need a HD SYE kit...

Seriously, unless there's some data or evidence out there that suggests that the option I'm suggesting would fail, I personally can't see why one would not want to do it? Perhaps cost? I'm not convinced that reliability is an issue. Or am I missing the point?
 
Go have a chat with South Bay Driveline, near the Arena. At least that way, you'll be dealing directly with the person doing the work.

Also, if you're interested, I can come up with an early NP231 that should replace your NP242 neatly, it came out of an 88. Swap you even - but you should probably verify input shaft "stick-out" before you take the thing, since I seem to recall there were two or three versions. Should be in good shape, but (me being me,) I'd rebuild it anyhow. In fact, that's what it's sitting around waiting for - rebuilding as a spare.

If nothing else, I can have a look at it and give you a second opinion late next week (after finals.) Let me know, OK?

5-90
 
RedFive said:
But what would that reason be? That Tom Woods wants to sell his setup? Again, I don't need a HD SYE kit...

Seriously, unless there's some data or evidence out there that suggests that the option I'm suggesting would fail, I personally can't see why one would not want to do it? Perhaps cost? I'm not convinced that reliability is an issue. Or am I missing the point?
Click to expand...

I suggest calling and talking to the man himself. Tom will not blow smoke up your rear. I'm not going into detail, but I spoke with him on the phone some time back and he explained it to me. He then sent me a very detailed e-mail explaining everything as well. Call him, a phone call is cheap.

As far as the H&T, you should be in the green. If all your XJ is going to do is pound pavement you should not have a care in the world about durability IMHO. There are many who wheel their rigs hard with a 242 and the H&T with no issues. So, I can't see how your mall crawler should have any either.

X2 on the TC drop and shims. Have you tried those options yet?

BTW, what is the purpose of a sky high XJ that does nothing but mall crawln'?
I never understood that.

Not busting balz, just curious.
 
5-90: Thanks for the reference on the shop. I'll check it out. Have you heard of Bay Shore Truck? Just got that reference a moment ago. I'll let you know if I need the other DS. Good luck on Finals.

cLAYH: I did not consider a TCase drop. Actually, I wasn't really sure if that would be enough to fix the problem. I'll look into it and ask about it when I talk to a shop.

Haleyes: The Jeep really isn't that tall. I'm just running 31s. You gotta' remember that the stock suspension had the Jeep slammed like a staion wagon and so the lift it has now is not really turning it into a sky scraper. Like I said in my original post, I use the Jeep to get around in the snow, do some light trails when I go out fishing...sorry if that makes me a target for "busting balz." I'll give a Tom Woods a call when I find some time, thanks for the suggestion.

TnSJ
 
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I run a H&T with a HAD shaft and its been perfectly fine even with 33s.
 
TC drops are band aids. I put one on for a year, but don't run it permanently. I don't know what your aversion is to H-n-ts if you don't need anything heavy duty. I made my own yoke, but you still have to cut the shaft and bolt on the yoke. It is a perfectly fine solution for most wheelers, and you say you will only be doing light duty stuff. To have a shop put a CV on your shaft will run you about as much as buying a new shaft. Just get the HnT and a new CV shaft and you will be set. You could do it for cheap and get an adapter and run a front shaft in the rear. You are sort of going for a complicated solution to a real easy problem. Hope this helps.
 
RedFive said:
5-90: Thanks for the reference on the shop. I'll check it out. Have you heard of Bay Shore Truck? Just got that reference a moment ago. I'll let you know if I need the other DS. Good luck on Finals.

cLAYH: I did not consider a TCase drop. Actually, I wasn't really sure if that would be enough to fix the problem. I'll look into it and ask about it when I talk to a shop.

Haleyes: The Jeep really isn't that tall. I'm just running 31s. You gotta' remember that the stock suspension had the Jeep slammed like a staion wagon and so the lift it has now is not really turning it into a sky scraper. Like I said in my original post, I use the Jeep to get around in the snow, do some light trails when I go out fishing...sorry if that makes me a target for "busting balz." I'll give a Tom Woods a call when I find some time, thanks for the suggestion.

TnSJ
Click to expand...


Bay Shore Truck sounds vaguely familiar, but I've dealt with SBD more.

I wasn't offering up a driveshaft (I've got a couple spares, but they're OEMR) but a transfer case swap. If you need more options for the rear output, getting the NP231 will help you.

5-90
 
5-90 said:
Go have a chat with South Bay Driveline, near the Arena. At least that way, you'll be dealing directly with the person doing the work.

Also, if you're interested, I can come up with an early NP231 that should replace your NP242 neatly, it came out of an 88. Swap you even - but you should probably verify input shaft "stick-out" before you take the thing, since I seem to recall there were two or three versions. Should be in good shape, but (me being me,) I'd rebuild it anyhow. In fact, that's what it's sitting around waiting for - rebuilding as a spare.

If nothing else, I can have a look at it and give you a second opinion late next week (after finals.) Let me know, OK?

5-90
Click to expand...

there is no option in the matter, 231 shifts way better than the 242...
i did the same swap (years and everything) and it matches up fine. you don't have to rebuild anything unless you think its been abused very badly....
i have 6 inch re long arm and did a one inch drop on the xmember longer yoke and haven't had a problem yet... but the only differences between the 2 i have noticed is the shifting and the 231 doesn't have 4 wheel part time...thats where the 242 messed up for me.
 
gwilliamson said:
there is no option in the matter, 231 shifts way better than the 242...
i did the same swap (years and everything) and it matches up fine. you don't have to rebuild anything unless you think its been abused very badly....
i have 6 inch re long arm and did a one inch drop on the xmember longer yoke and haven't had a problem yet... but the only differences between the 2 i have noticed is the shifting and the 231 doesn't have 4 wheel part time...thats where the 242 messed up for me.
Click to expand...

Er - the NP242 doesn't have "Full Time" 4wd - you might have gotten your modes confused there.

I could use the NP242 anyhow - I need another one. I've got one in line for rebuilding when I restomod my wife's 89 Limited, and I'd like another for when I build up our "travel rig" (we tend to drive cross-country, rather than fly. More fun, and I just HATE airports. I enjoy flying, I just hate airports. Zimbu the Monkey working security doesn't do much for my peace of mind, and having to leave all equalisers behind when I travel doesn't do much for it either...)

I'm not sure what shape the NP231 I've got is in - and if you're going to flog it, I'm fairly sure you'll at least want a new chain and mode fork pads. If you're going to tear it that far down, might as well overhaul the thing. I've got a loose one that was behind a Peugeot gearbox, and I'm about to pry loose another one (the one behind the AX15 is going to go in my 88 when I get the swap done - after I finish the front end on the second 89 to-morrow...)

So, like I said, I'll swap you straight up if you are interested - since I'm going to overhaul the 242 anyhow (if I get it...) I don't mind so much. The spline count on the input should be correct for you - I just don't know about the stickout on your case - the AW4 had two possibilities as I recall - "flush" and somewhere around 1" to 1-3/8", I think. Information can be found on the two possibilities (and a rare third!) at Advance Adapters (Google them - I don't recall the URL.)

5-90
 
5-90 said:
Er - the NP242 doesn't have "Full Time" 4wd - you might have gotten your modes confused there.

I could use the NP242 anyhow - I need another one. I've got one in line for rebuilding when I restomod my wife's 89 Limited, and I'd like another for when I build up our "travel rig" (we tend to drive cross-country, rather than fly. More fun, and I just HATE airports. I enjoy flying, I just hate airports. Zimbu the Monkey working security doesn't do much for my peace of mind, and having to leave all equalisers behind when I travel doesn't do much for it either...)

I'm not sure what shape the NP231 I've got is in - and if you're going to flog it, I'm fairly sure you'll at least want a new chain and mode fork pads. If you're going to tear it that far down, might as well overhaul the thing. I've got a loose one that was behind a Peugeot gearbox, and I'm about to pry loose another one (the one behind the AX15 is going to go in my 88 when I get the swap done - after I finish the front end on the second 89 to-morrow...)

So, like I said, I'll swap you straight up if you are interested - since I'm going to overhaul the 242 anyhow (if I get it...) I don't mind so much. The spline count on the input should be correct for you - I just don't know about the stickout on your case - the AW4 had two possibilities as I recall - "flush" and somewhere around 1" to 1-3/8", I think. Information can be found on the two possibilities (and a rare third!) at Advance Adapters (Google them - I don't recall the URL.)

5-90
Click to expand...


Damn - I thought I'd gotten that backwards. See what happens when you hit your head really hard? I've been told it takes years to heal...

The NP231 lacks the "Full Time" mode - the front and rear outputs are locked together, which is why it ends up grenading when run for long periods on dry pavement. The NP242 has the "Full Time" mode - which is, effectively, "All Wheel Drive," and can be run on dry pavement without incident (although it is still not recommended - it's not truly AWD, but it's got a differential in the case that the NP231 lacks...)

5-90
 
Dirt Surfer said:
TC drops are band aids. I put one on for a year, but don't run it permanently. I don't know what your aversion is to H-n-ts if you don't need anything heavy duty. I made my own yoke, but you still have to cut the shaft and bolt on the yoke. It is a perfectly fine solution for most wheelers, and you say you will only be doing light duty stuff. To have a shop put a CV on your shaft will run you about as much as buying a new shaft. Just get the HnT and a new CV shaft and you will be set. You could do it for cheap and get an adapter and run a front shaft in the rear. You are sort of going for a complicated solution to a real easy problem. Hope this helps.
Click to expand...


I guess I would agree that the TCase drop is a band aid solution...it seems that since the prob is with the DS that's where the fix should be focused.

As far as my adversion to HnTs, I read in the forums about these things wobbling and coming loose once in a while. Probably pretty rare. I hear what you're saying on the cost of what I'm proposing equating to that of a HnT/CV conversion but my whole philosophy is all about reliability (recall: "daily driver") and so if there's a solution that's more reliable in the long run I'll go that way instead. It seems like lengthing the DS and adding a CV joint could be an option for what I need.


- Now that I've had the time to read everyone's responses it sounds like what I originally proposed would work. So I guess the question is not "would it work" but really, "how reliable would it be?" It seems that the closer I keep it all to stock, without cutting/modifying the output shaft the better, right? My problem is that I just can't see why more guys are not doing it this way. I really feel like I'm missing something...is it cost?

TnSJ
 
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5-90 said:
Bay Shore Truck sounds vaguely familiar, but I've dealt with SBD more.

I wasn't offering up a driveshaft (I've got a couple spares, but they're OEMR) but a transfer case swap. If you need more options for the rear output, getting the NP231 will help you.

5-90
Click to expand...

Sorry for the confusion, I thought we were talking about a DS swap. I'm going to hang onto the 242...the full-time 4wd is an option that I do use on occasion.

TnSJ
 
RedFive said:
Sorry for the confusion, I thought we were talking about a DS swap. I'm going to hang onto the 242...the full-time 4wd is an option that I do use on occasion.

TnSJ
Click to expand...

Damn. I like having the option available as well - given the way people drive out here, I like to have every advantage I can...

5-90
 
I've been running a 3/4" t-case drop for 3 years now and its been fine. The only reason I pan to upgrade is so that if I lose my rear shaft I can continue on without worrying about losing the t-case oil.

I don't see a problem with running a t-case drop long term.
 
cLAYH said:
I've been running a 3/4" t-case drop for 3 years now and its been fine. The only reason I pan to upgrade is so that if I lose my rear shaft I can continue on without worrying about losing the t-case oil.

I don't see a problem with running a t-case drop long term.
Click to expand...

I think you answered the question as to why more guys are not just replacing the Ujoint with a CVjoint and lengthing the DS on their rigs...a broken rear DS means the yoke slips out and you loose your TCase as well, doesn't it? The HnTs kits as well as the HD SYE kits help to eliminate this, don't they?

I really don't anticipate putting my Jeep in a sitch. that could result in a broken DS, but as I was just preaching about reliability I may have to rethink this a bit.

TnSJ
 
RedFive said:
I think you answered the question as to why more guys are not just replacing the Ujoint with a CVjoint and lengthing the DS on their rigs...a broken rear DS means the yoke slips out and you loose your TCase as well, doesn't it? The HnTs kits as well as the HD SYE kits help to eliminate this, don't they?

I really don't anticipate putting my Jeep in a sitch. that could result in a broken DS, but as I was just preaching about reliability I may have to rethink this a bit.

TnSJ
Click to expand...

There is more to it than that. We have been talking possiblities. Just because it is possible does not mean it is a good solution. Others have thought the same thing, but I have never seen anyone do it.
By removung the slip from the TC and putting it on the DS, it lengthens the distance to the pinion. That helps reduce angles a bit.
CV joint themselves are heavier, and put more of a strain on the TC output bearing. By removing the slip from the TC, you move the CV closer to the bearing and reduce the stress.
You have repeated you want reliability. I would be much more concerned about heavier CV joint at the end of a shorter DS hanging off the end of a slip yoke, than I would be by a HnT. You are right about there being problems w/ HnTs. Unfortunately, us 242 guys don't have many options. Plus, there are 1000s out there w/ no problems. I like my yoke. You could easily do it. I believe it to be stronger. You would still have to find a output seal as you know.
 
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