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Old 01-03-2013, 04:04 PM   #1
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NP231J Grenaded

Was cruising down the snowy/icy highway yesterday in 4-Hi when the blast from what could only be described as the sound of all of a B52's engines suddenly erupted from the underside of my TJ. Fluid sprayed out both sides and has coated the underside and rear of my jeep, while chunks of aluminium rocketed in all directions. I believe this is a fine example of a grenaded transfer case. Fluid was regularly changed, internals were all replaced last summer, no noticeable signs of eminent destruction were provided. I guess the years of daily driver and Moab, CO, OH, and PA abuse finally caught-up to the casting in the front housing.
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Old 01-03-2013, 04:06 PM   #2
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Wow. Any sign of internal damage?

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Old 01-03-2013, 04:08 PM   #3
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Wow did it ever.
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Old 01-03-2013, 04:11 PM   #4
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this type of t-case failure is usually caused by lack of maintenance of front driveshaft u-joints/cv assembly.
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Old 01-03-2013, 04:26 PM   #5
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My driveshaft started making squeaking noises the other day. Took it off and have it at the shop getting rebuilt. My brother owned the jeep before me and that happened to him. Sorry man
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Old 01-03-2013, 04:40 PM   #6
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UnlimitedLJ04, I can assure you that my driveshafts and their u-joints and centering balls are regularly lubed, serviced and replaced when necessary. The front driveshaft had all three u-joints and the centering ball & saddle replaced just three months ago, and had it not been slammed around into my skid and various exploding shrapnel, it'd be bolted into the new T/C. Blanket statements like yours are the reasons I distrust forum advice, and for any newbies reading this post, I wish you'd qualify your comment.
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Old 01-03-2013, 04:45 PM   #7
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MarkNog, no verdict yet on the internals but I'm hoping the scratches on the chain are the extent, as I rebuilt this case in July using the JB Master Kit and other a la carte pieces (all new bearings, screen, seals, snap rings, slides / guides, cogs, shift rail & fork, etc). I'll disassemble it tomorrow to get a body count. I'll likely pull the SYE and all the good parts from this case, clean & inspect them, lube em, bag em and tag em for future replacements on my next T/C.
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Old 01-03-2013, 04:48 PM   #8
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Baker3, it sucks that the PO didn't keep up on the PM for your jeep. Good thing you're staying in top of it.
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Old 01-03-2013, 04:51 PM   #9
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I wouldn't be surprised if the failure was caused by a casting flaw in the aluminum case.
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Old 01-03-2013, 04:55 PM   #10
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Jerry, I agree - the main crack started at the base of the drain hole boss and extended all the way around, seemingly loosely following one of the spider veins in the casting. The edges of the tear don't look terrible, but I'm no metallurgy specialist. There don't appear to be excessive voids or anything, from what I see.
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Old 01-03-2013, 04:57 PM   #11
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Quote:
Originally Posted by PGH-TJ View Post
UnlimitedLJ04, I can assure you that my driveshafts and their u-joints and centering balls are regularly lubed, serviced and replaced when necessary. The front driveshaft had all three u-joints and the centering ball & saddle replaced just three months ago, and had it not been slammed around into my skid and various exploding shrapnel, it'd be bolted into the new T/C. Blanket statements like yours are the reasons I distrust forum advice, and for any newbies reading this post, I wish you'd qualify your comment.
qualify my comment how?

my statement is the truth, and every t-case i've seen do this was a driveshaft problem. my friend's t-case blew similar to that on the highway doing about 75mph.

here's more examples:
Broken T-case pics - JeepForum.com

The fact that the front shaft was rebuilt recently and the t-case blew up actually makes one wonder if something was done wrong...or maybe the rear needed addressing. cases' don't just blow up for no reason. is there any wear on the bottom edge where the chain may have rubbed?
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Old 01-03-2013, 04:57 PM   #12
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Jerry, here are some better-focused shots of the metal's edge:
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Old 01-03-2013, 05:04 PM   #13
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UnlimitedLJ04, the rear is a TW unit and I inspected it closely after pulling it - all the joints are good and tight. Also, the SYE shaft is nice and tight and the yoke has no play. Though I did torque-spec each bolt on the rebuild, I suspect the case failed due to stress of the casting itself - even the tail bearing for the front output shaft is still intact and pristine. It's a mystery. I looked at both ends trying to find the source of the failure and all I can find is the crack starting on the rear case half at a weak point (base of a boss) and extending to the front.
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Old 01-03-2013, 05:09 PM   #14
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If this had happened to mine, I would seriously be thinking ATLAS!
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Old 01-03-2013, 05:10 PM   #15
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The original T-case on my jeep looked very similar. It was the front shaft that failed on mine. Is everything else intact? Reason I ask is when mine was blown to smitherines there were numerous wires shredded too. Might be a good idea to check and make sure. Also there is a company I ordered my rebuilt T-case for 450 shipped. Good luck man I feel your pain.
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Old 01-03-2013, 05:10 PM   #16
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As far as internal scar from chain rubbing, I don't expect to find any, since I just replaced the old stretched-out chain this past summer, but I'll post the internal findings after I split the case halves and take inventory.
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Old 01-03-2013, 05:13 PM   #17
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Mwashburn, I also had that thought. But at $2746.19 for an Atlas 2 (just built one online as a TJ replacement with 3.8:1 gearing) I'm thinking this beast lasted 10 years, and for 1/5 of the price I can replace it with another 231, I'm leaning toward another 231.
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Old 01-03-2013, 05:20 PM   #18
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Baker3, the wires are all fine, I keep them zip tied up and out of harm's way. My Novak Cable Shifter was snapped off, the center support tunnel of the skid took a major whooping, and the leading edge is slightly deformed from the impacts. I just Simple Green'd the entire underside and washed it down. After it dries tomorrow, I'll look closer at everything because I hate getting dripped upon, lol.
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Old 01-03-2013, 05:38 PM   #19
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Im not a metal expert but I have seen cast alum fail in different machinery and that is what it looks like happened in the picture you have provided. It can micro fracture and spread like a tree root in the ground, until it cant hold and then it fails. I was also thinking it might be a good time for an atlas tc however you have made a very good point on prices. I think I would still get an atlas in the end but thats just me.
Good luck brother, can wait to see the real damage.
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Old 01-03-2013, 08:12 PM   #20
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Originally Posted by UnlimitedLJ04 View Post
qualify my comment how?

my statement is the truth, and every t-case i've seen do this was a driveshaft problem. my friend's t-case blew similar to that on the highway doing about 75mph.

here's more examples:
Broken T-case pics - JeepForum.com

The fact that the front shaft was rebuilt recently and the t-case blew up actually makes one wonder if something was done wrong...or maybe the rear needed addressing. cases' don't just blow up for no reason. is there any wear on the bottom edge where the chain may have rubbed?
I'm with you and I don't really care how long ago anything was built or rebuilt. You and I combined have probably seen this exact carnage over the years at least 20 times and it's always the same thing.

I will always admit there is an exception to everything, but I'd still be very curious as to the current state of the front DC joint in regard to viability.

The other telling circumstance is the front output side of the case being blown off the side of the case. Any other damage would not result in that type of failure. Certainly the rear output failing isn't going to shear off the front output, neither is chain failure, or much else other than the DC locking up or a front end impact that shoves the driveshaft back.
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Old 01-03-2013, 09:38 PM   #21
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Quote:
Originally Posted by UnlimitedLJ04 View Post
this type of t-case failure is usually caused by lack of maintenance of front driveshaft u-joints/cv assembly.
I came in to say this very thing.

Quote:
Originally Posted by PGH-TJ View Post
The front driveshaft had all three u-joints and the centering ball & saddle replaced just three months ago
This is no guarantee of exoneration for your driveshaft.

To wit: I decided to have my current TJ's front driveshaft rebuilt a couple of months ago at a local reputable shop. Within a couple weeks of installation, I began to get a chirping noise from under the Jeep during decel. After some experimenting, the noise went away when I removed my newly-rebuilt driveshaft... so I took it back to the shop. It checked out okay, they said, so they greased all the zirks again (?) "just on general principle." When I reinstalled it, the noise was now gone.

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Blanket statements like yours are the reasons I distrust forum advice, and for any newbies reading this post, I wish you'd qualify your comment.
Ease up there, Hoss. These guys are sharing relevant experiences which directly relate to what you're seeing, experiences which align with what others (such as myself) have also witnessed--I bought my fourth TJ with a blown up transfer case, and it was caused by (you guessed it!) a seized front driveshaft.

Maybe your front driveshaft is to blame; maybe it isn't. Either way, I wish you wouldn't be so quick to attack them for making "blanket statements" and giving solid advice.
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Old 01-03-2013, 10:23 PM   #22
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I know I don't have the "number" of post to be rated as an expert or anything. But, I agree with you guys on this. Improper maintenance.

PGH-TJ Out of curiosity, how fast was you going in 4H and was there any recent work done to the front end? (new gears, bearings, etc)
Also, don't get mad over the crap people say on the forums. It's just the stupid internet.
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Old 01-04-2013, 08:31 AM   #23
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I know I don't have the "number" of post to be rated as an expert or anything. But, I agree with you guys on this. Improper maintenance.

PGH-TJ Out of curiosity, how fast was you going in 4H and was there any recent work done to the front end? (new gears, bearings, etc)
Also, don't get mad over the crap people say on the forums. It's just the stupid internet.
The speed in 4hi has very little to do with it. As near as I can tell, all of the previous ones that have been posted failed in 2 hi or just being towed behind a motorhome. The front axle still turns the front shaft no matter what unless you have hubs.

One in particular though did die right after some hard use getting out of a stuck using 4hi and then hopped on the highway. It blew up right after.
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Old 01-04-2013, 04:24 PM   #24
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Quote:
Originally Posted by Sherpa View Post
I came in to say this very thing.



This is no guarantee of exoneration for your driveshaft.

To wit: I decided to have my current TJ's front driveshaft rebuilt a couple of months ago at a local reputable shop. Within a couple weeks of installation, I began to get a chirping noise from under the Jeep during decel. After some experimenting, the noise went away when I removed my newly-rebuilt driveshaft... so I took it back to the shop. It checked out okay, they said, so they greased all the zirks again (?) "just on general principle." When I reinstalled it, the noise was now gone.



Ease up there, Hoss. These guys are sharing relevant experiences which directly relate to what you're seeing, experiences which align with what others (such as myself) have also witnessed--I bought my fourth TJ with a blown up transfer case, and it was caused by (you guessed it!) a seized front driveshaft.

Maybe your front driveshaft is to blame; maybe it isn't. Either way, I wish you wouldn't be so quick to attack them for making "blanket statements" and giving solid advice.
He may need to explain to his wife why the metallurgy just exploded or just a pride issue! Don't need to convince us!
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Old 01-06-2013, 06:36 AM   #25
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Thanks everyone for your help. I caught the flu the day after pulling the TC, so I haven't made it down to the garage to tear into it and confirm/refute your thoughts. Thanks for backing-up your statements with links and other instances, I think it helps everyone to see what you based your comments upon. And if your guess turns-out to be have been correct, I'll let you know.

How fast? 67ish
Explain to the wife? Nah, I don't have that burden, just a single guy with no one to answer to - except my wallet.
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Old 01-06-2013, 06:55 AM   #26
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Thanks everyone for your help. I caught the flu the day after pulling the TC, so I haven't made it down to the garage to tear into it and confirm/refute your thoughts. Thanks for backing-up your statements with links and other instances, I think it helps everyone to see what you based your comments upon. And if your guess turns-out to be have been correct, I'll let you know.

How fast? 67ish
Explain to the wife? Nah, I don't have that burden, just a single guy with no one to answer to - except my wallet.
FWIW I am not able to "side" one way or the other......Basically because RARELY does something like this happen with these TC...however when I think about the obvious experience of the OP and where it has been wheeled, it comes to mind that it is a machine/ and machines do break and wear out, it is a fact of life.

Is it POSSIBLE a mistake was made 6 months ago when it was repaired, yes but not likely...same as it is not likely that it just "let go" as it rarely happens.

So I am waiting for more info...and hope to learn from another Jeepers experience.

S'cribed.......

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