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i was told the opposite. that bc of adjustable control arms i can adjust them to get a correct pinion angle?
It's true. You will be able to adjust pinion angle with adjustable CAs. But there's other issues you need to address.

Does your factory driveshaft have a u-joint on both ends? I have a 2001 and it did. I'm just not sure if some form of CV was added in the later years of the TJ.

If your DS is like my factory DS you want both u-joints to have identical angles. Other wise you will get vibrations. If you have some kind of CV on the t-case end of the DS you want your pinion angle to be as close to 0 degrees as possible.

Another thing to keep in mind. With a 4" lift and a slip yoke you're going to get vibes anyway. You need an SYE to allow for a longer DS or a t-case drop like mentioned above. Either of those will lessen the angles of the u-joints which will reduce vibes.
 

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i was told the opposite. that bc of adjustable control arms i can adjust them to get a correct pinion angle?
read the link. you can adjust the pinion angle, but that won't matter much because the misalignment is too high without a big t-case drop...or just get a SYE/CV shaft.

It's true. You will be able to adjust pinion angle with adjustable CAs. But there's other issues you need to address.

Does your factory driveshaft have a u-joint on both ends? I have a 2001 and it did. I'm just not sure if some form of CV was added in the later years of the TJ.

If your DS is like my factory DS you want both u-joints to have identical angles. Other wise you will get vibrations. If you have some kind of CV on the t-case end of the DS you want your pinion angle to be as close to 0 degrees as possible.
No factory TJ/LJ got a CV/double cardan shaft on the rear. Both NV241OR's and NP231's have single cardan rear shafts.

And yes, you can adjust pinion angle with adjustable control arms, but that won't help when the misalignment of the single cardan shaft is too great.


basically: if you can't reduce the misalignment of the ends, you need a double cardan shaft. that is why t-case drops are included in many cheapo lift kits....
 

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i installed a 4" lift with all 8 adjustable arms. i have no SYE and stock shafts. what should the pinion angle be?
4" lift with 1" TC drop and the pinion angle is 11*

It's as close to an accurate measurement as I could get for you, using my driveline to measure from. I don't have any vibes, but all our vehicles respond differently to lifts :hide:
 

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TJDrillSergeant said:
i was told the opposite. that bc of adjustable control arms i can adjust them to get a correct pinion angle?
Iv read that before also that a adjustable control arm will skew the camber in such a way to reduce the pinion angle. My only concern is how severe you would have to camber bc that creates it's own set of problems.

Iv heard many people removing vibs with new motor mounts. This could work if the new mounts help reduce the pinion angle by adjusting the natural engine resting position. This, again, has it's own problems.

I think your right in that a TC drop could help but it's all subjective to your wrangler. For instance: I lifted my rig 3.5" and the RE kit included a 1" tc drop. I ended up getting bad vibs especially when the engine was torquing in low gears. My pinion angle was to acute even with only the 2.5" gain.

I believe the best solution is to spend the money the first time for a sye and double cardan drive shaft. I read the DYI thread and followed it strictly which resulted in no more vibs at all. This solution ensures there is no bearing wear and directly fixes the problem without additional issues arising.

Hope this helps.
 

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Discussion Starter · #10 ·
yea with tax return ill get an SYE and cv shaft. but for the next two weeks ill throw a tc drop on and readjust my rear uppers. i plan on getting a mml and 1.25" bl to run my full belly skid
 

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Attempting to adjust your rear pinion angle is highly unlikely to produce the results you need. The problem a 4" lift causes is an excessive angle at both driveshaft u-joints, which is the root cause of vibrations, not so much a bad pinion angle. A 1" t-case drop will not be enough either.

There is far more to correct drivetrain geometry than most Jeepers are aware.
 

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Discussion Starter · #17 ·
thanks. gonna do a few more minor mods to complete the lift with taxes and then run a full belly skid. when you coming home?
 

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got about 5 weeks left i hope
 

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Hey folks, I wanted to share my experience in adjusting the angle on my '05 4cyl with a Rubicon Dana 44. After installing a 2.5 inch rough country lift, the relative pinion and TC output angles were 12 and 5 degrees respectively.

I purchased JKS rear upper control arms to correct the resulting vibrations and overshot in shortening the OEM length on first attempt.

After adjusting length from OEM 13 1/4 to 12 3/8 the pinion shifted from 12 to 2.7 deg... Ooops!

According to my calculations that's 10.6 deg / inch of UCA length for my setup, which should actually be a good starting guide for others.

Thought I'd share as these are the ballpark calculations I was looking for when embarking on the job myself.

Cheers & happy tooling,
Mike
 
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