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Unread 09-17-2013, 11:41 AM   #1
STRRAYNGE
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1993 ZJ 
 
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Jeep ZJ bad vibe issue in the rear! Need help

Ok, my ZJ suddenly a really bad vibration. I had taken it on the trails weekend before last, but didnt do anything that caused any damage. All was fine up until this past Friday. I was heading to work and noticed a really bad vibration coming from the rear. It starts at about 50 mph to 55, then goes away again until I hit about 65. Ive crawled under it, put it on jack stands, ran it up to speed while on stands, but cant really see what it could be. I can feel it though. Its driving me crazy trying to diagnose this issue. I did notice a growl in my diff, and plan to change carrier and pinion bearings this weekend, but is there something im missing here. (Due to the recent flooding here in Colorado, my wheeling season is over, but I really need to get this fixed so im not left stranded since it is my DD.) Please let me know if you need more info.

(This is a 93 ZJ with a Ford 9" rear axle and Currie High Pinion center section)

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1993 Jeep Grand Cherokee ZJ. 7" Clayton Long Arm Lift, 9" rear w/currie high pinion, D44 Trussed front axle, High Steer, chrome moly axles front and rear, ARB's front and rear, 35" BF Goodrich KM2's, Trail Ready front bumper with winch, custom rear with swing out tire carrier, etc, etc.
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Unread 09-17-2013, 12:33 PM   #2
JohnnyZJ
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why don't you start with teh easy stuff before you rip apart a whole diff.....................

rotate tires see if it goes away. maybe you screwed up a tire. OR
you have a bad ujoint. both of which will take you an hour to determine and will be a hell of a lot easier than rebuilding a diff.
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Unread 09-17-2013, 01:27 PM   #3
speedbucket
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Bad u joint or bent driveshaft.
If you have a double cardan rear shaft (sye on case) then check the slip splines and centering ball on double card an joint
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V8 zj at 6" . Double tri rear and true 3 link front. Stretched to 108"
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Unread 09-17-2013, 02:28 PM   #4
STRRAYNGE
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Quote:
Originally Posted by JohnnyZJ View Post
why don't you start with teh easy stuff before you rip apart a whole diff.....................

rotate tires see if it goes away. maybe you screwed up a tire. OR
you have a bad ujoint. both of which will take you an hour to determine and will be a hell of a lot easier than rebuilding a diff.
My rear is growling pretty loud, so I plan to at least change bearings out soon. But yes, I will rotate tires this afternoon and see if they are the culprit. I actually just rotated them a couple weeks ago, but this sudden vibration just started a few days ago. Maybe I slung a weight? I appreciate the info.

Quote:
Originally Posted by speedbucket View Post
Bad u joint or bent driveshaft.
If you have a double cardan rear shaft (sye on case) then check the slip splines and centering ball on double card an joint
I do have the double cardan and SYE. I know the splines are pretty tight, and it doesnt move as free as it should, so I will pull it this afternoon and try to get it moving freely. Is there a way to check that centering ball on the cardan? I just got off the phone with Tom Woods, and he also said maybe the centering ball. Once again, I appreciate the info and will report back with what I find.
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1993 Jeep Grand Cherokee ZJ. 7" Clayton Long Arm Lift, 9" rear w/currie high pinion, D44 Trussed front axle, High Steer, chrome moly axles front and rear, ARB's front and rear, 35" BF Goodrich KM2's, Trail Ready front bumper with winch, custom rear with swing out tire carrier, etc, etc.
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Unread 09-17-2013, 03:07 PM   #5
speedbucket
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It sits in the middle of the two joint at the case.
You'll know if its bad when you pull the shaft. It will flop around and not be smooth. Also check your pinion for tightness and your joint straps/u bolts so the joint sits tight in the yoke.
How's your 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 09-17-2013, 03:46 PM   #6
STRRAYNGE
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Quote:
Originally Posted by speedbucket View Post
It sits in the middle of the two joint at the case.
You'll know if its bad when you pull the shaft. It will flop around and not be smooth. Also check your pinion for tightness and your joint straps/u bolts so the joint sits tight in the yoke.
How's your pinion angle?
Pinion angle im going to try to adjust today also. It has the Currie high pinion center section, but it is actually, from what I think, tilted up too high. It was like this when I bought it, just havent had time to adjust it.
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1993 Jeep Grand Cherokee ZJ. 7" Clayton Long Arm Lift, 9" rear w/currie high pinion, D44 Trussed front axle, High Steer, chrome moly axles front and rear, ARB's front and rear, 35" BF Goodrich KM2's, Trail Ready front bumper with winch, custom rear with swing out tire carrier, etc, etc.
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Unread 09-17-2013, 03:58 PM   #7
speedbucket
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The pinion should be 90* perpendicular to the driveshaft on a double card an driveshaft
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V8 zj at 6" . Double tri rear and true 3 link front. Stretched to 108"
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Unread 09-17-2013, 06:58 PM   #8
STRRAYNGE
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quick update, not sure if it will fix my problem, but hoping. pulled rear shaft and the rear ujoint at the diff was seized on one side, and a little twisted. wife will be back shortly with a new 1310/1330 ujoint. as soon as i get it installed and test i will repost. im hoping this is it!! cross fingers.
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1993 Jeep Grand Cherokee ZJ. 7" Clayton Long Arm Lift, 9" rear w/currie high pinion, D44 Trussed front axle, High Steer, chrome moly axles front and rear, ARB's front and rear, 35" BF Goodrich KM2's, Trail Ready front bumper with winch, custom rear with swing out tire carrier, etc, etc.
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Unread 09-17-2013, 07:09 PM   #9
speedbucket
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Should fix it
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V8 zj at 6" . Double tri rear and true 3 link front. Stretched to 108"
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Unread 09-17-2013, 09:06 PM   #10
STRRAYNGE
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Fixed! Thanks for the replies!
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1993 Jeep Grand Cherokee ZJ. 7" Clayton Long Arm Lift, 9" rear w/currie high pinion, D44 Trussed front axle, High Steer, chrome moly axles front and rear, ARB's front and rear, 35" BF Goodrich KM2's, Trail Ready front bumper with winch, custom rear with swing out tire carrier, etc, etc.
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Unread 09-18-2013, 10:02 AM   #11
JohnnyZJ
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told you


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05' WK Hemi limited ~ wifey mobile
13' Chevy Cruze ~ boo
13' GMC Sierra ~ 2.5" lift 33" MTs.
RIP 95 ZJ ~ 33s built/longarmed/locked/awesome Feb 2014 ZJOTM winner
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Unread 09-18-2013, 11:43 AM   #12
STRRAYNGE
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Quote:
Originally Posted by JohnnyZJ View Post
told you


yeah, yeah, yeah, rub it in, lol! I didnt think ujoint originally because I crawled under it and checked it over, tried to move it, twist it, etc, but it didnt budge so I didnt suspect it. But, as soon as I dropped that shaft, it was immediately evident that was the issue, or at least one issue. Main reason I was dropping the shaft yesterday was I had spoke with Tom Woods, who builds custom shafts, and he mentioned dropping it, and running with just the front shaft to see if the vibes went away. So I was going to do that, but found it and fixed it! Once again, I appreciate the help from you guys!

(BTW: unfortunately I will still be pulling my diff apart due to the growling, but it will last me a tad longer)
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1993 Jeep Grand Cherokee ZJ. 7" Clayton Long Arm Lift, 9" rear w/currie high pinion, D44 Trussed front axle, High Steer, chrome moly axles front and rear, ARB's front and rear, 35" BF Goodrich KM2's, Trail Ready front bumper with winch, custom rear with swing out tire carrier, etc, etc.
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Unread 09-18-2013, 12:45 PM   #13
JohnnyZJ
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been there, done that.

once i was 'sure' i had grenaded my transfer case in my old YJ. as i was pulling driveshafts to replace the transfer case, found the rear was solid; ujoints were screwed. replace them, brand new jeep.

jeeps are funny that way i guess
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92 YJ ~ locked/33" swampers
05' WK Hemi limited ~ wifey mobile
13' Chevy Cruze ~ boo
13' GMC Sierra ~ 2.5" lift 33" MTs.
RIP 95 ZJ ~ 33s built/longarmed/locked/awesome Feb 2014 ZJOTM winner
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