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Discussion Starter #1
Ok so I've been pulling my hair out trying to get rid of this vibration. I adjusted my pinion angle 6 times this week trying to get this vib to go away. I just got some advice from a speed shop and it kinda goes against what I have learned in the past about how my pinion angle should be set so here goes.


Current set up:

19 Degrees (The pinion angle)
0 Degrees (difference between the dshaft and the pinion)
19 Degrees (angle of the dshaft)
12 degrees is the difference between the dshaft and the output
7 degrees (angle of the out put)

12 - 0 = 12 degrees
Total Operating Angle is 12 Degrees currently. The fella said that is wacked and I need to change my angles around so that the total operating angle is less than or equal to 3. Below would be where I would start if this doesn't prove to be a crappy idea.

I guess I should up the angles to.

10 for the rear axle
9 difference
19 for the dshaft
12 different
7 for the output

12 - 9 = 3
Total operating angle would be 3 degrees here and technically should work based on what the dude said. He also said to check and see if the rear axle is in line with the tcase. This is something I am going to check also. I'm going to drop some plumb lines to the garage floor and measure it up to see if I need to adjust my rear track bar.

See I think if I put the rear pinion angle down to 10 degrees that at full droop I may have issues with the ujoint binding up. What do you guys think.
 

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Discussion Starter #3 (Edited)
SYE

Yes sir the Rubicon Hack and Tap. If all of these tweeks don't work my next step is the AA Short shaft kit. I have the RE 4.5 with 4.56 gears and a CV drive shaft.
 

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I'm no driveshaft expert but your current setup looks dead-on, or at least close enough. Ideally, the rear pinion shaft should be 1-2 degrees under the driveshaft for a CV driveshaft but that's for decreased wear reasons, at least according to Tom Wood. That the rear pinion angle is exactly the same as the driveshaft is picture-perfect, though again the pinion shaft should be 1-2 degrees under the driveshaft's angle. But being exactly the same as they are now will not cause vibrations, the recommended 1-2 degree difference is, again, simply to allow the u-joint to lubricate itself a little more efficiently. The 7 degree anglular difference between the DS and t-case output shaft is divided in half by the two u-joints inside the CV... and 3.5 degrees per u-joint isn't bad at all.

Are you absolutely sure it's the rear driveshaft causing the vibration? How is the rear pinion bearing? Can you move the pinion shaft if you grab it? How's the front driveshaft and caster angle? If the caster angle was upped to bring it to the factory 7 degree angle, that could be causing front driveshaft vibrations due to the steepened front pinion shaft angle.
 

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Discussion Starter #6
I haven't checked the dog leg yet but it is suspect. I get the vibs throughout the rpm range but they really don't become a pain until highway speed. Which happens allot since I don't have a trailer and it's 2 hours to the closests wheelin spot.
 

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Discussion Starter #8
I took the rear dshaft out an the vibs are gone so it is definitly the rear end somewhere.
 

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I just got through with putting my new 60 in the rear of my TJ.


Pinion = 19 deg
shaft = 21 deg.

Not a vibration what so ever. Standard rotation also. When the 44 was in the rear I set up the pinion and the shaft to be the same. I DID have some slight vibes at around 65 or 70 but nothing bad at all..

Mabe that hack and tap you got is causing the problems.
 

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Discussion Starter #10
I hear that. The hack and tap sucks ass. But I didn't have the vibs when I first set up the kit so this is a development over time. Do you think I should even try to move my pinion down to 10 degrees or would that just be a waist of time. Maybe I should spend my time making sure the rearend is lined up with the crappy hack and tap.
 

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Discussion Starter #11
New Development

I just dropped a plumb line to the garage floor from the center of the crank and output and pinion. They all line up perfect. Ok now it seems that my only hope is that the AA SYE kit will fix my issue because it seems that everything else is fine. What do you all think of setting my pinion angle to 10 degrees. I really don't want to. It just doesn't seem right. I though that with the CV joint on the drive shaft I was just supposed to point the pinion directly at the output shaft.
 

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10 degrees.

Couldn't think of a bigger waste of time Glenn. Jerry brought up a good point. How's the pinion bearing? Mine sux.
 

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Discussion Starter #13
Jerry ... Sorry I didn't see your post before. I haven't tested the pinion to see if it's lose at all. I will do that. I think it should be fine thought because I have about 6k on the new gears. I will check though. I am going to buy the AA SYE kit. I figure it can't hurt my set up to upgrade even if it doesn't get rid of the vibs. They I would know for sure that it is the gears because the dshaft is fine when tested at the speed shop. They spun it at like 4000 rpms and it has around .0001 runout witch the dude said was cool.
 

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Glenn,

If the boss is in today:rolleyes: , I'll ask him about your operating angle. He seems to know his driveshaft sh!t. I assume they spun your driveshaft with the CV at 0 degrees. If your CV is worn, would it show up? Also if our driveshafts are the same, we could swap them at the otter, and you could run mine around and see if it makes a diff.:jeep: :D
 

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Discussion Starter #15
Your dshaft wouldn't fit the set up most likely until after I do the SYE. We can give that a shot. If this doesn't work then it has to be the pinion.
 

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The vibe is only when you step on the gas right? Set the pinion angle down a bit so that the pinion is 1 degree below the driveshaft angle. That should fix it.
That speed shop you are talking to are a bunch of morons - they obviously have never heard of a CV shaft. Sounds like they are tyring to give you tips to set up a conventional two joint shaft.

HTH,
Phil
 

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Discussion Starter #19
I have already done that. I have set it in 5 different locations. 19,17,15,14,13 degrees. 14 behaving the best out of all of them but the problem still there.
 

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Discussion Starter #20
I was kind pissed when the driveline all lined up yesterday because that ment I was going to have to toss some money at it so I just pushed the jeep out of the garage and praticed welding radom metal together. That always helps when I am frustrated.
 
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