NP231 Tcase splits

DonsYJbuild · 03-12-2010, 08:06 AM

My son's 91 XJ split it's transfer case while driving down the highway. It was not in 4WD. Has anyone ever seen a NP231 split in half? This XJ has a 6 inch lift and 35s. We have done a slip yoke eliminator kit on the output shaft of the tcase and replace that drive shaft. But we have never changed the front drive shaft. We also have a Tereflex long arm kit up front that has been adjusted to move the front axle back where it should be after moving from 4 inches of lift to 6 inches. My quess is we ran out of extension on the front drive shaft and that caused the tcase to split. Any ideas or suggestions are appreciated.

**elkfan2** · 03-12-2010, 08:52 AM

Or the CV joint in the front driveshaft seized up and when that happended it caused bad things to happen.

**Unlimited04** · 03-12-2010, 09:29 AM

Quote:

Originally Posted by elkfan2

Or the CV joint in the front driveshaft seized up and when that happended it caused bad things to happen.

yup, fairly uncommon...but it does happen.

http://www.jeepforum.com/forum/f9/broken-t-case-pics-979282/
http://www.jeepforum.com/forum/f9/transfer-case-broke-353516/

DonsYJbuild · 03-12-2010, 03:31 PM

Thanks for the replies. After thinking about the extra lift and resetting the front axle with the adjustable long arm kit, I bet I am out of extension on the driveshaft and that worn out the CV joint. I am going to have my son pull the front driveshaft tomorrow and we will find out.

Pillswoj · 03-13-2010, 06:41 AM

Quote:

Originally Posted by Unlimited04

yup, fairly uncommon...but it does happen.

http://www.jeepforum.com/forum/f9/broken-t-case-pics-979282/
http://www.jeepforum.com/forum/f9/transfer-case-broke-353516/

I would argue that it is extremely common for those that ignore their front driveshaft. I would bet that that 91 XJ had never had the centering ball rebuilt and after 19 years it seizing and splitting the TC is the expected result.

DonsYJbuild · 03-13-2010, 08:57 AM

I would have to agree with that assessment. After doing everything we have done I am embarrassed that we did not replace the front shaft. You drop the bucks for a long arm kit, new shocks/springs, SYE, new rear shaft, 35" tires, skid plates, bumpers, etc and yet we did ignore that front shaft. Well at least a got a good replacement NP231 for $125 and put the SYE into it. So other than the time and energy, not too much wasted. At least my kid and I got to spend time together working on Jeeps!

**Wheelin98TJ** · 03-13-2010, 10:37 AM

Did you guys rebuild the front driveshaft too?

DonsYJbuild · 03-13-2010, 11:35 AM

Nope. It is the original.

DonsYJbuild · 03-13-2010, 01:28 PM

Just got the old front driveshaft off and the centering ball is totally trashed. Time for a new shaft.

Thanks everyone for your input.