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Discussion Starter #1
I brought this issue up a while back, but no one had any ideas. Im hoping the pics and update will help someone, help me.

Jeep XJ with 700r4/350, 35", 9" lift, NP242 w/SYE tom woods,
D44 turned up.
I originally built the jeep in 1995 with 33" and 5.5" lift. I ran this combo for a long time with no issues.
About a year ago I lifted it to 9" lift, got a SYE/CV kit rebuilt the T-Case, changed the Tranny and motor mounts to soft style and added 35" tires. Since then I have cracked two tranny cases within 500miles. Internals are fine, and it only happens at highway speeds. It ran without vibes for a few hundred miles, then started vibrating badly, shortly after the first tranny cracked. When I put a new one in, it was still vibrating. It always cracks at the same place(towards the back right) and this time around it popped off the speedometer block off thingy. 700r4 has a AA kit mated to a NP242. I hate to put another tranny in without having an idea why it cracks. AA, Novak and every so called expert in town hasnt had a clue. If anyone has any ideas or knows of a shop that can help, it would be greatly appreciated
thanks
\\Hoot
http://www.commguru.net/~owl/
 

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damn that sucks

man thats shitty,

mabe its time for a nv4500(ohh yeah baby!!)? thats weird how a case splits like that, usually if the drivling are too short on the slip yoke, the tcase can actually crack/break, but i never hear of a tranny splitting unless it tries to fight a rock. mabe the case was already cracked and you didnt know it and it decided to crack more? i had a d35 traclock do that to me, the whole f ing carrier broke in half runnin a 4cyl auto carbed with 31" bfg bald terrains!
goodluck man

your xj sounds sweet! :eek:
 

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are there any signs of something striking it due to drivetrain flex (i.e. the soft motor mounts)

stiffer mounts (like poly/harder rubber compound) will give you more NVH, but It's probably worth it to keep this from happening.

You sure there's not runout somewhere, or an issue with your front or rear shafts being too long? Is there anything that takes a little extra effort to fit once it's all bolted together?
 

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OWL....
this is just conjecture, so youll have to bear with me...

if i remember correctly from reading your posts on NAXJA you run a SBC w. about 400 to the wheels, is that right?

what i wonder is what your setup is in the engine bay in terms of mounting the engine is...are oyu suing just the std AA motor mounts for XJ V8 or what?
ill cut right to the chase...
i think its a possibility that with the kind of power your mill pumps out it might distort/twist the engine bay section of the unibody a decent amount. then in turn the tranny/tcase is anchored in on the crossmember fairly securely.
my theory is that force might be enough to crack the tranny with alot of power.
let me know what you think and if this could indeed be possible.
~John
 

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Discussion Starter #6
My rear driveshaft is actually a "tug" to get it to line up. Last time it cracked, I didnt reinstall the front driveshaft.

as for the motor mount issue, yes I run a SBC with around 400hp. it only cracks at highway speed 65+. The first time it cracked I had Solid Motor Mounts and Soft Tranny Mount. I did run it for years with hard/hard mounts, though.
After it cracked I thought the same thing you did, so I put rubber Motor Mounts so that it would flex and move together.

There doesnt seem to be anything that could hit it. the way it looks to me, it seems like a hydraulic pressure crack, but Im running dual B&M supercoolers.
Anyone else have Big Lift and SBC/700R4 in there XJs?
I know people with 37s and AW4!!!!! Maybe I should get a KIA

Could the Transfer case with 4to1 Tera that was inporperly rebuilt cause this? im starting to think mebbe it needs a New rebuild by someone besides me
Thanks for the replies it is appreciated
\\hoot
 
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