JK: Caster and T Cases

[TipsE-Z]

Okay, so most of you know that I'm not really a mechanical guy. Honestly, I'm a bit of a dumb arse when it comes to mechanical things above changing oil, tires, bolts, etc. My T Case recently blew up. Like chunks of T Case housing laying on the interstate. From everything I'm reading online it has to do with my Caster not being set properly and causing a driveline vibration that eventually cracks the T Case resulting in this catastrophic failure.

I took the Jeep to Chrysler to get it covered under warranty (bought it "Certified Pre Owned) but they of course immediately stated "it's been off road and has aftermarket components, we aren't covering it". But that is an entirely different discussion that I will save for when I have more time to thoughtfully complain about MOPAR.

My question is: How difficult is it to set up the caster to ensure my pinion is pointed properly at the T Case. Depending upon how insurance (from when I flopped it and got a warranty on that work) decides to handle this I'm either SOL and going to have to buy an Atlas myself (not cool with a baby coming) or I'm probably going to end up with a new Rubi T Case. I'd really like to ensure that I have everything set up properly on this thing to avoid this in the future.

Thanks in advance folks.

[Elusive]

It's just not that hard to set up the caster. with the weight on the wheels and the driveshaft removed i put a broomstick from the pinion to the T case yoke. Then I adjust the upper control arms till the pinion yoke aims right at the T case.
If you don't have adjustable uppers, you could adjust only the lowers but the axle will move a bit (which is uaually OK).
Now a couple other questions..
1. did you have a stock front driveshaft? how many miles? was it worn out?
my front driveshaft only lasted about 30000 miles with a 3.5" lift and then a low milage replacement lasted another 15000 miles. in both cases the slip portion got loose and I could feel the driveshaft beginning to vibrate. This last time I spent some coin on real driveshafts.
2. try a different dealer. these warranty claims are almost completely up to that specific dealer. While the laws change from state to state, in CA they have to prove that the modifications caused the failure.
Gook luck with all of it.

[TipsE-Z]

I have adjustable long arms and an aftermarket drive shaft. I just checked the lube on the slip section on Sunday and all was well there. Sadly I bought the Jeep from an awesome dealership in AZ that I know would cover this, but this one didn't even want submit it to Chrysler to give you an idea of where they were at on it. I called Chrysler Corp and basically got the same answer. Sad thing is that I'd just went out of my way about 2 hours prior to take a photo of my Jeep in front of the big rock JEEP sign at the plant in Toledo, OH.

And thank you for the info on setting it up. I kept reading things about needing to cut C's and weld, and such which is all WELL above my mechanical ability.

[jonah]

You are talking about two different things here.

Caster is the angle that the front knuckles are at (think of the forks on a bike, same idea). This helps the front tires track in a straight line. The pinion angle is what can induce vibration in the driveshaft if set up incorrectly. Unfortunately they are both connected by the axle housing. You can adjust the pinion angle by adjusting your links but it will throw off your caster and could adversely affect the handling. There is a little wiggle room there so it could be ok if a small adjustment needs to be made, I am not sure the spec on JKs but average caster is between 4-7 degrees. So with a lift you will want to increase the pinion angle to get it lined up with the t-case. This will reduce the caster and can make the jeep wander. If the driveshaft is not lined up correctly it can vibrate. The only way to get both perfect is set the pinion angle then cut and re-weld the inner Cs at the correct angle.

I would think that keeping the caster correct and buying a quality driveshaft that has been balanced to a high standard would probably get you by without adjusting the inner Cs.

On the rear axle you can usually adjust pinion angle without too much concern if that driveshaft is a double cardan (CV) set up as well.

The front output of the t-case is where the failure occurred?

[jonah]

I assumed but I should have asked if your front driveshaft is a double cardan (CV), or if it has a single u-joint on each end. The pinion angle is set up differently for each.

[aw12345]

Okay, so most of you know that I'm not really a mechanical guy. Honestly, I'm a bit of a dumb arse when it comes to mechanical things above changing oil, tires, bolts, etc. My T Case recently blew up. Like chunks of T Case housing laying on the interstate. From everything I'm reading online it has to do with my Caster not being set properly and causing a driveline vibration that eventually cracks the T Case resulting in this catastrophic failure.

I took the Jeep to Chrysler to get it covered under warranty (bought it "Certified Pre Owned) but they of course immediately stated "it's been off road and has aftermarket components, we aren't covering it". But that is an entirely different discussion that I will save for when I have more time to thoughtfully complain about MOPAR.

My question is: How difficult is it to set up the caster to ensure my pinion is pointed properly at the T Case. Depending upon how insurance (from when I flopped it and got a warranty on that work) decides to handle this I'm either SOL and going to have to buy an Atlas myself (not cool with a baby coming) or I'm probably going to end up with a new Rubi T Case. I'd really like to ensure that I have everything set up properly on this thing to avoid this in the future.

Thanks in advance folks.

If the transfercase broke at the front driveshaft end, your front driveshaft had a cv joint/ centering ball failure. Fairly common thing

[TipsE-Z]

I do have CVs front and rear. And Jonah, thank you for explaining that. Now I understand why people were talking about both. I initially though I could set pinion angle with the control arms but when I started reading about cutting Cs I figured I'd either ended up in a rap video or in welding school; either one not being a good option for me.

Art, the T Case did bust at the front output shaft, this is sort of making me really want a different front axle/housing with manual hubs to take some parts of the equation out. Here's a few photos I took on the side of the interstate.



Picked this up off of the interstate.




And now that I'm looking at the photos it looks as if I was mistaken... I don't have an aftermarket DS up front. It looks to me like it is stock, but I'm pretty sure that anything above 3" on the JK requires a new front and rear.... Hmmm... I may have to look into this.

[1 Bad F N Z]

Boy that sucks, Kevin.

[TipsE-Z]

That it does. I just went over to look at things and I was initially correct in that I had aftermarket CV shafts front and rear. How does this change how you set things up? I'm being told that I may be able to get an aftermarket T Case to have put in instead of a factory T Case, anyone have any stories of bullet proof options? I'm leaning towards an Atlas 2, maybe a 4 if I can afford it.

[Russ Chung]

Chris,

I don't believe that the vibrations from the front driveshaft could cause a catastrophic failure of the T-case. If the pinion angle was wrong, I would think that you would have felt the vibrations long before it would have caused the T-case to crack. If the centering ball on the double cardan u-joint was failing, you would have heard a chirping sound known as "angry birds" and you would have definitely felt an abnormal vibration; it happened to my Jeep when I had a stock front driveshaft. I drove it from Los Angeles to Phoenix before I had a chance to crawl under the Jeep and troubleshoot the problem, so I'm pretty sure that you would have had plenty of warning if pinion alignment or worn u-joints were causing driveshaft vibrations.

I can't tell from the picture but I'm guessing that the catastrophic failure of the T-case was due to a failure of the front bearing, probably caused by lack of oil or contaminated oil.

Have you seen this article on Tom Woods' website that explains the difference in pinion alignment between single and double cardan driveshafts?
http://4xshaft.com/JR7_TW_Driveshaft.pdf

Russ

[aw12345]

Chris pretty sure your front driveshaft cv joint failed. If you take the front driveshaft out you will see that the CV joint is seized, bet ya money on it, Centering ball welded it self to it's cup. Seen it before, not all that uncommon, it.s about the only thing that will cause the transfecase to break like that

[TipsE-Z]

Chris,

I don't believe that the vibrations from the front driveshaft could cause a catastrophic failure of the T-case. If the pinion angle was wrong, I would think that you would have felt the vibrations long before it would have caused the T-case to crack. If the centering ball on the double cardan u-joint was failing, you would have heard a chirping sound known as "angry birds" and you would have definitely felt an abnormal vibration; it happened to my Jeep when I had a stock front driveshaft. I drove it from Los Angeles to Phoenix before I had a chance to crawl under the Jeep and troubleshoot the problem, so I'm pretty sure that you would have had plenty of warning if pinion alignment or worn u-joints were causing driveshaft vibrations.

I can't tell from the picture but I'm guessing that the catastrophic failure of the T-case was due to a failure of the front bearing, probably caused by lack of oil or contaminated oil.

Have you seen this article on Tom Woods' website that explains the difference in pinion alignment between single and double cardan driveshafts?
http://4xshaft.com/JR7_TW_Driveshaft.pdf

Russ

Russ, good to know info there. Thank you for sharing the article, that's written in a manner my nerd brain can comprehend. I guess this is part of the problem with cheating and buying a Jeep that was already built; but thankfully I knew the original owner and all the shops that did the work on it as it was all "professionally built". I found it pretty hard to believe that the front drive shaft caused a vibration bad enough to cause this type of failure, specially without me noticing. The Jeep dealership that first looked at determined that the 1/4" thick skid plate (a good bit beefier than factory) had been mashed into the Transfer Case and caused it to crack... I found this hard to believe, but I'm by no means a mechanical guy.

Chris pretty sure your front driveshaft cv joint failed. If you take the front driveshaft out you will see that the CV joint is seized, bet ya money on it, Centering ball welded it self to it's cup. Seen it before, not all that uncommon, it.s about the only thing that will cause the transfecase to break like that

Art, I didn't even think to try to playing with my shaft yesterday. I should have wiggled around the the double cardan a bit to test it out. I may run back over to the Nissan dealership USAA had the Jeep brought to and check out the front shaft a bit closer. I need to go discuss with them the options of putting an Atlas in the Jeep anyways. MOPAR wants ~$3050 for a new factory T Case, 500 of which is a core charge that I'm told will most likely not be given since the case is in chunks. This is good news for me when I'm wanting to beef it up with an Atlas so I don't have to worry so much in the future.

[aw12345]

No decent 4x4 place in your neck of the woods to do the install? Having a dealership do this is kinda iffy. They have no clue about fabrication and what not

[TipsE-Z]

There is but the work is being handled under a warranty from all the post flop work. There is a shop my dad had do all the work on his but I don't think I can go anywhere else due to the warranty issue. All this is assuming they cover it since MOPAR denied it already.

[Zoobi]

One other thing to consider. If the front drive-shaft was too long, It will bottom out and crack the case housing. If they replaced the drive-shaft after the repair, its possible they got a longer one due to the lift and screwed up the measurement. I use to see that when we would get lowered trucks in the shop where they didn't have the rear shaft shortened. It would break the trans tail shaft off when hitting bumps.


Scott