Driveline Vibration

[GB.XJ.MI]

So my 97 XJ with 203,XXX has developed a pretty bad drive line vibration at anything over 65 MPH. The XJ is bone stock with the upcountry package and some 31 BFG ATs. I have a front and rear JCR bumper with a homemade tire swing and a winch. The driveline vibrates so much i tear the rear pinion seal and leak fluid at anything over 65 MPH for about 5 miles or more. Since this is my DD and i use it to tow with and what not i have air shocks in the back to level out the sagging leafs. my pinion angle doesnt seem to be off at all. The u joints have about 22,XXX miles on them. ive put 3 seals in the rear axle (D35) and want to get the vibe taken care of so i can travel long distances on the highway. trans mount? drive shaft out of balance? or is my D35 a pos like any other and crapping out?

help, suggestions, and tips would be great!

[Mudderoy]

So my 97 XJ with 203,XXX has developed a pretty bad drive line vibration at anything over 65 MPH. The XJ is bone stock with the upcountry package and some 31 BFG ATs. I have a front and rear JCR bumper with a homemade tire swing and a winch. The driveline vibrates so much i tear the rear pinion seal and leak fluid at anything over 65 MPH for about 5 miles or more. Since this is my DD and i use it to tow with and what not i have air shocks in the back to level out the sagging leafs. my pinion angle doesnt seem to be off at all. The u joints have about 22,XXX miles on them. ive put 3 seals in the rear axle (D35) and want to get the vibe taken care of so i can travel long distances on the highway. trans mount? drive shaft out of balance? or is my D35 a pos like any other and crapping out?

help, suggestions, and tips would be great!

If you balance and rotate the tires, does the vibration improve?
If you get under the Jeep and push and turn on the drive shafts do you have any play in the u-joints?
Is there ANY gap between the u-joint cap and the yoke?

3304

See that little gap? That was enough to make the center console rattle, since I have replaced the yoke and have a tight fit with the u-joint, it's a much smoother, quieter ride.

You mentioned leaf spring sag, I don't think so but if the pinion angle is out more than 3 or 4 degrees difference than the transfer case then you'll get vibrations.

Oh and I think motor mounts and transmission mount can play into the vibration issue.

[NW99XJ]

DANG, THIS IS A TOUGH ONE.....
So it sounds like you have no lift....
If assuming thats true, then what we're looking at in one of three things.
1.) you have extremely bad luck with U-joints, and they need to be replaced again (all of them)
2.) your pinion yoke is toast...meaning the races that hold the U-joints in place are worn, and not keeping things tight when they should.
3. you DO have a driveline that is out of balance.

I may consider taking the driveline off, and taking it to a driveline shop to have it tested/rebalanced.
I may also consider swapping that rear pinion yoke with one from a junk yard, just for the sake of elimination....see if that fixes things. That should be less than $10 ...and an hour or two of your time.

I would ordinarily suggest taking of the rear driveline and going for a quick test drive to see if the issue is isolated..... I THINK that the rear of the late model Cherokee T-cases are sealed..... cant remember now, been a while since I tore into one.

[GB.XJ.MI]

hmm.... good to know that little gap created all that vibration! and thanks for the quick reply. The tires are all balanced and just rotated last oil change. doesnt seem to worsen or help the issue. i will for sure check the other things. im hoping its something simple but never usually is. I have the factory upcountry package and am running air shocks in the rear just to level the jeep out.

[Mudderoy]

hmm.... good to know that little gap created all that vibration! and thanks for the quick reply. The tires are all balanced and just rotated last oil change. doesnt seem to worsen or help the issue. i will for sure check the other things. im hoping its something simple but never usually is.

When was the last time you changed the rear diff fluid? Was there any metal shavings in the oil? Did you notice any unusual wear on the ring gear? Are you hearing any noise from the rear diff?

Yeah I guess it could be a pinion bearing.

[GB.XJ.MI]

Gosh it's gotta be getting close to changing. But it's always full and looks alright. Shavings not really. But let's say worse case the pinion bearing is bad. I have a Chrysler 8.25 laying around for this vehicle as a precaution lol. Has anyone swapped a d35 out to a Chrysler 8.25 with a np242 t case? Do i need a custom length drive shaft? I have one out of a 231 Chrysler 8.25 I could use.

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[NW99XJ]

The 8.25 has a slightly longer pinion than the 35..... but the driveline conifg is different depending on the transmission I think... the case size is basically the same between the 241 and the 231.
But I would say it's time to get that 35 out from under there, and get that 8.25 in regardless. (just so long as the gears in it match whats up front)

[GB.XJ.MI]

True. Sorry 241***

Thanks for the quick responses. I'll try to get at it this week and find the problem and report back. At the cost of seals, I suppose a axle swap is cheaper in the long run.

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[TheDude]

This gave me some good ideas of things to check for on mine!

[GB.XJ.MI]

So I crawled under the XJ today and my pinion bearings feel fine. U joints look good. However where the splined end slips on the tail to the t case there is some slop there. And with the rear axle floating the t case makes some pretty bad sounds but is fine when there is load. So I'm kind of at a loss and don't want to take it to m driveline shop locally and spend a ton of money. To me there is so much slop on the spline end, but who knows... Any suggestions?

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[Mudderoy]

So I crawled under the XJ today and my pinion bearings feel fine. U joints look good. However where the splined end slips on the tail to the t case there is some slop there. And with the rear axle floating the t case makes some pretty bad sounds but is fine when there is load. So I'm kind of at a loss and don't want to take it to m driveline shop locally and spend a ton of money. To me there is so much slop on the spline end, but who knows... Any suggestions?

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Did we ever get you to check drive line angles? The pinion angle vs. t-case angle? Also have you tried removing the front driveshaft then driving it? Could be the vibration isn't coming from the rear.

[GB.XJ.MI]

I've removed the front awhile ago for the same reason and it didn't go away. Its a stock jeep other than the air shocks but pinion angles looks straight. I wonder if the splines on the output shaft on the t case has worn out or the splines on the drive shaft. I can move it up and down there. And Btw I have a np242. Its the full time option.

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[4.3LXJ]

Try greasing the splines. Sometimes that takes the play out of them

[NW99XJ]

Any chance you could get a video of this play?
Make sure the lighting is good, and the camera is focused well on the area in question.
Post it up to youtube, and link it to here.
Might give some of us a better idea of what we're trying to troubleshoot.

[GB.XJ.MI]

Well i took a video and the audio quality is horrendous when the actual noise happens. I guess it's at a frequency where my phone mic won't pic it up. This is when I had the vehicle on jack stands and in gear. Now I can take a different video with me under the Jeep wiggling the drive shaft if you'd like.

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[NW99XJ]

Yea I think I'd be more interested in SEEING what has play and how much, as trying to listen to what a noise is.... and you're right, cell phone mics down often times pick up some of the sounds that really make up what is causing the issue. Nothing beats first hand, but a visual inspection via video I think is about as good as we can get right now.
(unless you want to fly me out there and back real quick...) :D

[GB.XJ.MI]

So it's been quite awhile since an update. So I replaced the trans mount and fought my crossmember off because I bent it from a wheeling trip. Ended up pulling one out of a junkyard and installing that. I get less vibrations but they're still there at 60mph and above. U joints? Rear axle?

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