Bad NP 231

hbc2

Well-Known Member
Joined
Mar 23, 2007
Location
Siler City North Carolina
I'm having trouble with my NP 231 transfer case. Are there any heavier duty swaps rather than rebuilding the 231? I'm running 35's with 4:56 gears on a TJ. I read about he rubicon's NP 241's, but I can imagine they're hard to find.
 
Anything good is hard to find. A Dana 300 with a flip kit is a good option. Some people have bad things to say about the D300, but if your NP231 is holding up, the D300 will be fine. It is a cast iron, gear driven case.
 
What trouble are you having with your np231. For what your running I cant imagine having much trouble. An np231 is actually a fairly decent case for what it is.
 
You can put a heavier/wider chain in them, and beef the output. As posted what problems are you having? The 4:1 kits replace the front 1/2 with a beefy(er) casting.

With the tires/gears your running I don't think your doing anything to the case anyone else isn't already... If your case has high mileage you might just try a rebuild, any other used case is likly going to need a few parts to get it trail ready.
 
NP231

Going down Daniel (at a slow crawl) at Uwharrie, it popped out of low range, and would not go back in at all. 2WH and 4WH were working fine. I thought the shift linkage had slipped. We tried every possible position on the linkage, then 4WH quit working. It would just grind like 2WLow, and not engage. We disengaged the shift linkage completely and tried to engage 4WH and 4WLow manually, with no luck. It only has 76k miles. We have not cracked into it yet.
 
I just fixed a wrangler for a guy that had the exact same problem. Turned out that he had been rearended and the drive shaft pushed into the tail housing. It went far enough in that it pressed the output bearing in about 3/8 of an inch. So now with the bearing in too far the snapring was not holding the main shaft back, when you shift from low to high the shift fork moved the whole mainshaft back and forth instead of moving the the shift collar on it. In your case you could have the same problem if the snapring against the output bearing is broken or missing. Its something simple to check so it might be worth looking into.
 
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