Transfer Case Issues

Last summer I installed a RE 3.5" super flex kit on my 99 xj, and did a tcase drop and all the normal stuff to when u first lift it. But when i was wheelin it just after thanksgiving the front output side of my tcase broke off. I had a tcase and front drive shaft installed that i got off a junkyard 99 xj with 55k on them. Every thing was fine till this past week when leaving work i started getting the same vibs i had the last time it blew up. I towed it to a shop in my town and they said vibs were most likely coming from the tcase and also that my front axle yoke was being streched to the max and causeing that seal to start leaking, and my rear axle yoke is being compressed. need help trying to figure out why this is happening and what to do to fix it.

Hmm.. assuming what the shop people told you is right, thats pretty odd to my familiarity of the XJ's construction. Im just going to rattle off a few things that may be contributing factors... Engine mounts, make sure they are not worn. To my understanding the tcase/transmission/engine are basically one solid item, all held inplace by the engine mounts, and your t-case drops. Make sure they are all tight.

A friend of mine is running a 3.5" lift with a 1 inch t-case drop. These drops are a cheap alternative to a slip-yoke-eliminator (SYE) at this lift hieght. Anything over this height of lift, you pretty much have to do SYE. But, the problem you describe, I don't think an SYE would help. Sure can't hurt by putting on one though, and getting rid of your t-case drops.

Lastly, usually when that portion of the t-case breaks off, its called "gernading" the case. If you are in 4x4, making a sharp turn, and on rock/pavement, this is where the drive line unloads (typically). Were you in a situation like this when you broke your case?

Hopefully you get more responce... Like I said, all I have said are suggestions... I am not a XJ doctor haha but, there are a lot of people on here that are very knowlegable. They could probably give you better advice. Best of luck to you!

Make sure your driveshaft is not too long. As the XJ suspension extends, the driveshaft gets shorter. If the driveshaft binds it tries to shove the driveshaft into the transfer case resulting in catastrophic failure of the t-case.

I was driving down the high way when the t-case went. And they're the stock drive shafts

You don't use 4WD on the road do you?

no only use it on the roads when 2wd cant get me though the snow.

I don't see how at 3.5"s of lift your rear axle yoke could be to far compressed. Should be going the other way. Either something very odd is going on or they fed you a line. Do you have the rig at home or the shop? Take a look or get them to show you what they are talking about.

I would think that you would feel if the yoke was bottoming out.

Wait a minute. The yoke is in the middle of the drive shaft in the front. How would it leak oil?

no its the seal where the drive shaft and the axle link up that is leaking. and not sure if its fully compressed but at least thats what i was told. still have to get iy towed home to investgate myself

So here's what i think, but i may be wrong. Your 99 has a low pinion D30 correct? Then it will have a harsher pinion angle when lifted than a high pinion will. And when you did the t-case drop that will help with rear pinion angle, but actually worsen the front pinion angle. Because as you angle the back of the assembly down the front of it will have to angle up, because as mentioned before the engine, tranny, and t-case are all one piece when assembled.

The t-case drop will also put more stress on the engine mounts because of the same reason i mentioned before. Add on top of that poorly designed and problem prone stock mounts, i'd give them a looking at.

Also check the rubber mount that sits between the cross member and the tranny, i haven't seen it happen really, but it is possible that has gone sloppy allowing movement of the whole drive train. Which would only be made worse if your motor mounts are toast.

This is interesting, cause a 3.5" lift shouldn't really give you that much trouble as far as vibes and really bad pinion angles...

I don't trust mechanics, just because i've been fed a lot of crap by them trying to get me to pay them to fix a nonexistent problem, so i'd defiantly give it a good look over when you get it back. Or if you're not sure about what your angles should be, i'm sure a member near you could donate a half hour or so to eyeball your setup.

halvey88 said:

no its the seal where the drive shaft and the axle link up that is leaking. and not sure if its fully compressed but at least thats what i was told. still have to get iy towed home to investgate myself

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Are you talking about the pinion seal in the front drive shaft? Most all the ones I've seen leak. As long as it's not dumping fluid I'd just give the level a check now and again to make sure it doesn't run dry. Changing the seal out isn't rocket science either if you go that rout.

What nochance9 said is good stuff too. And like he mentioned 3 1/2" lift shouldn't be causing you that much trouble. I have no doubt that you have issues but I think you need to look elsewhere from the lift.

Did they have Dana 35 axles under the 99's? With ABS right? The driveshafts are different lengths for the 35 or the Chrysler 8 1/4. Is it possible you got the wrong one at the junk yard?

nochance9 said:

the t-case drop will also put more stress on the engine mounts because of the same reason i mentioned before. Add on top of that poorly designed and problem prone stock mounts, i'd give them a looking at.

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they replaced the motor mounts just prior to me getting the jeep in 08.

jonnyghost said:

Did they have Dana 35 axles under the 99's? With ABS right? The driveshafts are different lengths for the 35 or the Chrysler 8 1/4. Is it possible you got the wrong one at the junk yard?

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im not sure if they did or not but ive got a d30 up front and a 8 1/4 in the rear. dont have abs either

nochance9 said:

So here's what i think, but i may be wrong. Your 99 has a low pinion D30 correct?

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99's have HP30's...

dgrigorenko said:

99's have HP30's...

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Hmmm..... my bad. Thought that 99 was the year they decided to go to the LP D30. :anon:

This is a tough one and i'm running out of ideas as to it's possible cause.

im not sure if they did or not but ive got a d30 up front and a 8 1/4 in the rear. dont have abs either

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I'm wondering because I believe the dana 35 found in the rear of some jeeps has a longer drive shaft. If you'r parts vehicle had a dana 35 and you have an 8 1/4 then that could explain why your slip yoke is bottoming out.

when it blew the first time i only replaced the front driveshaft because it was getting noisy. and also since it was the front output that broke off.

wow...somewhat confusing. Now, if I've understood all the posts so far, your current issue is that you're getting vibrations, and the shop guys said it was your transfer case, and that your driveshafts are 'bottoming out'.

Now, a lift will tend to extend driveshafts, which would make stock shafts very unlikely to 'bottom out'. If they meant 'bottom out' in the sense that they're at their maximum extension of the slip yoke, then I might understand. And, if that is the case, vibrations could be the result of worn slip-splines. If the splines are worn, you will get high speed vibes, and the more a shaft is extended, the more effect the worn splines will have.

Now, if your front differential pinon seal is leaking, the front pinon bearing may be going south, causing the pinon shaft to 'wobble', which will be felt like a vibration, and which will take the seal out with it. If you pull the front driveshaft and the vibration goes away...then you've narrowed down the problem. I'd suggest pulling the front shaft and examine (feel) if there's side-to-side slop in the slip yoke, and while it's out, grab and see if there's movement on the axle pinon. Then drive to see if vibration is gone.

ok so at this point i have been unable to find the exact location of the problem any everything seems to be right minus the over extrention and compression. would it be a save bet to say that just need new driveshafts that are the correct length? well that and a tcase since the other one is shot. will deffinatly be looking SYE route this time too. how do i measure for drive shaft length?

halvey88 said:

how do i measure for drive shaft length?

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http://www.4xshaft.com/index.html