Dinghy transfer case exploded

CVD, that sounds like what happened to mine, The front shaft was replaced when it was repaired. on my old chevy the CV joint had a needle grease fitting and it was occasionally greased. never greased Dakota, there were no grease fittings or a place to put them unless it was ever replaced with a non factory item.

The NP 231 transfer case is vulnerable to catastrophic problems (explosion) when the front drive shaft CV ball freezes. This is the ball between the double u-joint at the transfer case end of the front drive shaft. They are usually good for many years, but when they start “chirping” or “singing”, it’s time to change those u-joints and centering ball.

I’ve not heard of this problem when towing the jeep, but is certainly is possible. As stated earlier in this thread, the front axle shafts, differential gears, and drive shaft are always spinning in most YJ’s and TJ’s (only aftermarket hub lockout can change this). If the driveshaft freezes at the point where it connects to the transfer case, it will rip the TC apart.

Here’s a thread on this subject: http://www.wranglerforum.com/f5/np-231-explosion-193097.html

enblethen wrote:
I am not sure about all Jeeps, but normally you would not be in fifth in a five speed transmission. Fifth may not stop gears from turning. That is over drive. Previously transmsion would be in fourth.

I have towed my Jeep several thousand miles with the tranny in 6th gear.
No problems.
My previous Jeep ('95 Wrangler SE) had a five speed, and I towed it in 5th gear.
Again, no problems.
Why do I put the Jeeps in "top gear"? Because, if the unthinkable and impossible SHOULD somehow happen, and the transfer case dropped into gear (or I forgot to put it 9in NEUTRAL), I don't want the engine turning at 10,000 RPM in some lower gear!
It is just "cheap insurance"!

The same thing happened to me on the way home from Arizona 150 miles from home. After towing my 93 Dakota 4x4v8 from Apache Junction to Kankakee.Il. my transfer case let go also. I had towed it to and back from Arizona the previous year and all over Michigan for 9 years so I knew how to set it up. The next exit was a Dodge dealer. The tow truck driver dropped it off there, this was on a Sunday. I picked it up the following Saturday after paying 2400 dollars. This was in 2004.

wilanddij wrote:

OP wrote:
It's a 1999 Jeep wrangler and he is towing it behind a class A. He was going down the road at 65 when bam the transfer case let go. He said transfer case was in neutral and the tranny was in 5th.

I have a hard time believing this is operator error. A Wrangler TJ ('97 - '06) is about the easiest of Jeeps to tow. Xfer case in neutral, tranny in gear (or Park), and key one click toward start.
If the xfer case was not in neutral to start with, I think something else would blow well before reaching 65mph.

The later JK's are even easier, as they don't have a steering lock and a plug and play wire harness is available from COOLTECH.

OP wrote:
It's a 1999 Jeep wrangler and he is towing it behind a class A. He was going down the road at 65 when bam the transfer case let go. He said transfer case was in neutral and the tranny was in 5th.

I have a hard time believing this is operator error. A Wrangler TJ ('97 - '06) is about the easiest of Jeeps to tow. Xfer case in neutral, tranny in gear (or Park), and key one click toward start.
If the xfer case was not in neutral to start with, I think something else would blow well before reaching 65mph.

X2. I'd agree the T-Case was probably not in Neutral.

havasu wrote:
I hate to say this but I would lay good odds on it being operator error - sorry.

I hate to say this but I would lay good odds on it being operator error - sorry.

I was adamant that I had unlocked the steering on my GC until the front tire exploded - I realized what I had done but never admitted it (until now LOL)

I am not sure about all Jeeps, but normally you would not be in fifth in a five speed transmission. Fifth may not stop gears from turning. That is over drive. Previously transmsion would be in fourth.

j-d wrote:
Does the Jeep have front locking hubs that should have been disengaged so the two axles were in neutral from each other, as well as the TC itself in neutral from the transmission?

Didn't some TCs use a drive chain, like a timing chain? I can see where a badly worn one could drop and make a real mess.

j-d,
Unless the owner changed the front hubs, the factory ones are not like the old style of "locking" hubs. They haven't had those since the demise of the "CJ". The YJ, TJ and JK units all don't have those locking hubs. The engagement of those axles is all done from in the cab and Jeep/Chrysler have altered the mechanism over those years.

As for the transfer case. If it's a bone stock unit, that transfer case in a TJ is what's known as the 231. That T/C HAS a built in oil pump just inside the rear output shaft housing. It's a very thin, rotary vein pump. The transfer case itself is aluminum and yes, it does utilize a CHAIN for the main drive in it. They do get loose but, usually not that loose that they can jump or skip teeth, like a timing chain can in an auto engine.

Without seeing that transfer case in a "Phorensic" autopsy, it's hard to give a good analyzation of just what the cause was for it's demise. If the person did in fact, place that transfer case in neutral, and placed the trans in 5th, then it's technically done correct.

As for the T/C being able to "self engage" into gear as you're towing it down the road, well, that's just about a million to one possibility. There's a few zillion Jeeps of all years and models being towed every day all over this country and the reported "self engaging" transfer case ordeal, you could count on less than one hand.

It would be interesting to hear what the cause was.
Scott