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Discussion Starter #1
Okay, I have searched all everywhere and can not find any answers. I hope someone can help.
I have a 2001 WJ lifted 6 inches, with 32's. I have the 247 T case, which has a slip yoke. I have had the drive shaft lengthened.
The front shaft still has plenty of length.
Now what is happening is, when I get on the freeway I have no vibes at all when on the gas or when coasting, but when floating between gas and coast there is a strange vibration (noise) that sounds like metal on metal.
The first thing I did was I replaced my rear upper control arm and because it was close enough that I thought it may be hitting. Then I replaced the driver motor mount, because I noticed it had more travel than it should. This whole time I have laid under the Jeep for hours trying to find the problem. I replaces the fluid in the rear and the front pinions, I have checked the T case fluid. The only other thing I can guess could be is the front upper control arms have (connected to the long arm and the axle) some slack in the bushing at the axle. It is a floating gap bushing and I think it should be a no-gap bushing.
Again this only happens between 60 and 80 ish, and only when floating the gas It sound like it is coming from the rear, but I can not tell for sure because if it was coming from the front the vibe could radiate through the LCA’s to the unibody.
If you have any Ideas I’d love to hear from you.

Thanks,

Ron
 

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sounds like a drive shaft angle problem , even tho i never liked shims but you may have to put one in the rear ,also getting rid of that slip yoke may do it but alittle costly but first try to rotate your axle a few degrees
a pic of your drive shaft will help with seeing whats up with the problem
 

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Sounds like a simple u-joint. How is there condition? You have a d44 in the rear of that too right? Maybe the yoke tabs have spread and you need a new yoke. Buy the one with the u-bolt straps. It's only like $30 bucks
 

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Discussion Starter #4 (Edited)
I thought it was a drive shaft issue, and I did play around with the Drive shaft angles which makes no difference. Right now the tcase is at 7 degrees and the axle is at 8 degrees which is OMHO 2 degrees too high. but like I said it really did not make much of a difference.
I did not think about a U joint. How can I tell if it they are bad? They appear to be tight in the rear yoke and they are a bit loose in the slip yoke. Maybe that is it?
I'll give u joints a shot, adn I'll post a shot of the DS here in a bit.
Thanks
 

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Discussion Starter #5
Here is the photo of the Driveline
 

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Discussion Starter #6
The sound as far as I can tell sounds like it is comming from directly over the rear end, but it is a unibody so it is very hard to tell. I changed the rear Universal joint last night and no change this morning. While the drive shaft was off I checked the pinion by hand and and it does have some play but it does not seem excessive from what I can tell. What gets me is that it is only when floating the pedal between gas and coast. I have gone through and tightend every suspension bolt I could. The only hting that comes to mind about the time this started was the addco rear sway bar. Maybe i'll remove it and see if that makes a difference.
 

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I have a 94 wrangler with spring over and 2.5 springs and some shackles. About 9 inches of suspension lift and 38.5 tsl's. I still have a slip yoke and i know that is against everyones jeep rules but it works just fine for me. And yes it is a daily driver. I have the pinion set pointing directly at the t-case did this when i lifted the jeep the first time becuase i was planning on a new driveshaft and slip yoke eliminator. But it worked well enough with just slight vibrations. Will cruise just fine at 70-75 on the highway. Anyways has worked fine for about 2 months now no problems what so ever. I dunno may work for you.
 

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from what your saying if i would say you have something loose in the drive line because if you can get to 60 without a bad vibration i would think the driveline angle is ok. grab your drive shaft and try to move it without the tires moving if you can twist it than its the u joints. if you can move it up and down than its either the pinion bearing or the output bearing on the t case .
 

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Ron4x4 said:
Here is the photo of the Driveline
looks like you need to point the pinion towards your t/c ,you have two conflicting angles on your driveline, also a cv drive shaft will cure your noise
from the vibration
 

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Discussion Starter #10
Hendo said:
looks like you need to point the pinion towards your t/c ,you have two conflicting angles on your driveline, also a cv drive shaft will cure your noise
from the vibration
I thought you were only suppost to point the pinion to the TC if you have a CV drive shaft?
 

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Discussion Starter #12
Okay after reading through those links and tons of threads. I should have my transfer case and pinion parallel, since I do not have a CV joint. Which right now the pinion is 1.5 degree high. I also I need to take care of that and then if the cosign of the operating angle is more that 15 Degrees I would need a CV joint on the Drive shaft. Right now the TC is 7* and the pinion is 9* so that is 16 Degrees.I need to take the pinion down to 7* or 6* to make the over all 13-14 degrees. According to the Tom woods link I will get rid of the "fluttering" Noise.
Does my thinking sound right to you all?
 

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Discussion Starter #13
Drive line guys does this sound right?
 
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