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Unread 07-09-2013, 07:48 PM   #1
Kuchara
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1997 TJ Wrangler 
 
Join Date: Jun 2012
Location: , Utah
Posts: 1
Bad Vibrations at 30+ MPH

(First time poster, and beginner Jeeper.... so no abbreviations on parts please :P )

Some background! Yay!
1997 TJ Wrangler Sport
It has been lifted at least 1.5". When whomever did the lifting, they didn't touch the rear control arms, drive shaft, or the rearaxle-to-body mount (Dont know the name: IMAGE HERE Note hole with missing bolt)... causing a lot of vibrations when I would start moving forward from a dead stop. The axle was rotated up, making the drive line go almost straight into the differential. Its like they wanted to put a double u-joint (cvjoint?) on the rear but never got around to it. Due to the rotated rear axle, the mount to the body was rotated out of place and I was unable to put a bolt through. This makes my back end to rock left and right as I drive (makes it hard to drive straight).
But... I was recently able to fabricate longer control arms so I could rotate the rear axle to be more horizontal. This will allow me to put a bolt back through the axle-to-body mount to keep my back end from swaying left and right. (Just havn't bought the nut&bolt yet).
Driveline is now too short though (Crappy image here. Note how far it sticks out of transfer case), and now I get horrible vibrations at 30+mph (at least the start-moving vibrations are gone). It also looks like there is an extra, wedge-shaped mount from my transfer case to the skid plate (wedge image . The engine-transmission-transfercase is angled up slightly toward the front.... making the transfercase-to-front driveline angle seem off. (Transfer case yoke points up, but the front driveline is angled down... like this image.


Short version: Problem: Bad drive shaft vibrations when I hit 30 MPH or faster. How do I fix it? I know I need to get a new drive shaft (or get mine extended), but I want to fix any other related problems first so I can get the correct length.
Random Info:
Vibration is softer if I'm in 4wheel drive high (I was curious what would happen so I tested it).
Jeep is lifted (unsure of how much... around 2 - 2.5 in).
I want to keep my differential and transfer angles parallel (see IMAGE) as that saves me a lot of money (don't have to get a double u-joint and new driveline).
Transfer case is lowered about an inch.
Engine-transmission-trasfercase are NOT parallel to the ground (due to wedge piece mentioned earlier I believe) Should they be?

I hope this actually makes sense to somebody lol.

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Unread 07-10-2013, 07:10 AM   #2
tyvanwie
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1998 TJ Wrangler 
 
Join Date: Sep 2012
Location: Boone, North Carolina
Posts: 9,481
Well that was a read. Too early for it :P But let me see if I understand. You have ~2" of lift (by the way you can know for sure by measuring the coils, anything over 12" front and 8" rear is how much you have), a 1" transfer case drop, and are getting driveline vibrations? For some reason the picture links aren't working on my phone. As I'm sure you know, the best thing to do is to get a SYE, new driveshaft, and adjustable rear upper control arms. Sorry if this wasn't much help, it's still early for me
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I'm pretty sure I know what I'm talking about. I think...
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Unread 07-10-2013, 07:41 AM   #3
MisfitSeven
MAIL Crawler.
 
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1998 TJ Wrangler 
 
Join Date: Feb 2009
Location: Bennington, Nebraska
Posts: 3,508
That wedge mount is stock.
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Unread 07-10-2013, 08:05 AM   #4
RnEmOvr
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1999 TJ Wrangler 
 
Join Date: Mar 2005
Location: Ft Stewart, Ga
Posts: 10,553
OK, some click free stuff.





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Unread 07-10-2013, 08:12 AM   #5
RnEmOvr
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1999 TJ Wrangler 
 
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The missing bolt is part of a rear track bar bracket. Looking at that angle I think you have more than 2" of lift. It also looks like the rear DS is about to pull off the shaft of the TC. The red springs say Skyjacker to me and SJ never made a 2" spring lift. The lower CAs look like these Teraflex arms.
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