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Unread 06-04-2013, 10:04 AM   #16
ZJMatt
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1998 ZJ 
 
Join Date: Jul 2012
Location: Weare, NH, New Hampshire
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I adjusted the front LCA's in about half an inch and it took up 0.1º of the difference between the pinion angle and driveshaft angle. Sounds pretty negligible to me...

I also calculated that by reinstalling the ½" transfer case drop that the p/o had installed that I took out, I can account for 1.3º.

At that point, it would still be 9.2º off and I'm guessing I'd still have issues... is it worth reinstalling the drop? I can't afford adjustable uppers right now.

Also, I noticed the u-joints are not "in phase" with each other. Could that be causing some vibrations, or is that not necessary with a double cardan joint?

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Unread 06-04-2013, 10:43 AM   #17
PolkaPower
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The front pinion should be pointed right at the t case as in pic B. The rear should look like A. If it's set up right you never need a t case drop which just negates the lift in the first place.
picture-18.png  
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Unread 06-04-2013, 10:56 AM   #18
speedbucket
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Quote:
Originally Posted by ZJMatt View Post
I adjusted the front LCA's in about half an inch and it took up 0.1º of the difference between the pinion angle and driveshaft angle. Sounds pretty negligible to me...

I also calculated that by reinstalling the ½" transfer case drop that the p/o had installed that I took out, I can account for 1.3º.

At that point, it would still be 9.2º off and I'm guessing I'd still have issues... is it worth reinstalling the drop? I can't afford adjustable uppers right now.

Also, I noticed the u-joints are not "in phase" with each other. Could that be causing some vibrations, or is that not necessary with a double cardan joint?
Use the adjustable lower s to get it as far back as you can. The "out of phase" is what I told you the problem was on the first page.
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V8 zj at 6" . Double tri rear and true 3 link front. Stretched to 108"
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Unread 06-04-2013, 11:03 AM   #19
ZJMatt
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Quote:
Originally Posted by speedbucket View Post
Use the adjustable lower s to get it as far back as you can. The "out of phase" is what I told you the problem was on the first page.
Shorten the CA's as far as they'll go? I feel like the tires are gonna rub...

I'll see about getting the joints in phase now and re-adjust the arms tomorrow when I have more time.
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Unread 06-04-2013, 11:16 AM   #20
speedbucket
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Quote:
Originally Posted by ZJMatt View Post
Shorten the CA's as far as they'll go? I feel like the tires are gonna rub...

I'll see about getting the joints in phase now and re-adjust the arms tomorrow when I have more time.
The joints won't be in phase unless you correct them to the proper angle shown to you in 2 different pictures now. If the uppers are stock then the lowers will end up close to stock length
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V8 zj at 6" . Double tri rear and true 3 link front. Stretched to 108"
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Unread 06-04-2013, 11:46 AM   #21
ZJMatt
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Quote:
Originally Posted by speedbucket View Post
The joints won't be in phase unless you correct them to the proper angle shown to you in 2 different pictures now. If the uppers are stock then the lowers will end up close to stock length
By in phase, I was talking about the pinion end u-joint being in phase with the double cardan end u-joint. I had the slip yoke apart, and when I reinstalled it I didn't have them lined up correctly.

In the process of pulling the shaft out and the slip yoke back apart, I found 2 of the 3 u-joints have play in them. They were fine when I installed them, I'm guessing driving around with vibrations caused them to go bad?
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Unread 06-04-2013, 11:55 AM   #22
speedbucket
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Quote:
Originally Posted by ZJMatt View Post
By in phase, I was talking about the pinion end u-joint being in phase with the double cardan end u-joint. I had the slip yoke apart, and when I reinstalled it I didn't have them lined up correctly.

In the process of pulling the shaft out and the slip yoke back apart, I found 2 of the 3 u-joints have play in them. They were fine when I installed them, I'm guessing driving around with vibrations caused them to go bad?
No, driving with an improper pinion angle killed them. You bind all three joints by not having the proper pinion angle.
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V8 zj at 6" . Double tri rear and true 3 link front. Stretched to 108"
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Unread 06-04-2013, 09:53 PM   #23
moldeck
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Same topic, but different problem. Had a U-joint problem in the front. Joints looked good but the pin and spring in the middle of the double U-joint was blown out causing a very bad vibration. Just an FYI if you are doing a search on drive shaft vib.
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Unread 06-04-2013, 10:19 PM   #24
ZJMatt
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Quote:
Originally Posted by moldeck View Post
Same topic, but different problem. Had a U-joint problem in the front. Joints looked good but the pin and spring in the middle of the double U-joint was blown out causing a very bad vibration. Just an FYI if you are doing a search on drive shaft vib.
Already replaced that, for the same reason.
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Unread 09-23-2013, 08:40 PM   #25
tevisesplin
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Try tightening the nut that holds the yoke to the t case front output shaft. my jeep would vibrate starting at 65 mph but wouldnt with the front shaft removed. tried all sorts of things but it seems tightening the front output shaft yoke nut did the trick. I have no idea what the torque spec is though.
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Unread 09-23-2013, 08:43 PM   #26
ZJMatt
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Quote:
Originally Posted by tevisesplin View Post
Try tightening the nut that holds the yoke to the t case front output shaft. my jeep would vibrate starting at 65 mph but wouldnt with the front shaft removed. tried all sorts of things but it seems tightening the front output shaft yoke nut did the trick. I have no idea what the torque spec is though.
Funny this thread gets bumped the day I finish my NP242 swap.

Now that I can have the jeep in 2wd, there is no more clunking noise. In 4wd it's still there, so it's definitely the bad pinion angle.
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