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Unread 04-06-2013, 07:43 AM   #1
Plyj
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1990 YJ Wrangler 
 
Join Date: Feb 2010
Location: Plymouth, MA
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Vibration after instal HD rear springs

Hey All -
'90 YJ w/ '89 Cherokee 4.0L (no rear track bar).
I had an issue with a dragging noise in the right rear for about a year... sounded like brake drum rubbing backing plate but much louder... whenever I made a left-hand turn or starting acelerating from dead stop. I never could trace it down but figured it was something rubbing against something else as the rear end moved up toward the body.

Looked at the el cheapo (4-leaf) rear springs and they were exactly flat (no arch at all) when Jeep at rest. So I got some Old Man Emu 5-leaf springs and put those in with new bushings, new rear brackets, and axle U-bolts (supposed to be only a 1/2" lift). When I got all this in, the rear was sitting at least 6" taller and the rear springs had a good deal of arch (shock absorbers would bolt on but just barely at full extension).

Took it for a drive... noise gone (for the most part) and now I have a noticable vibration... I assume from a much steeper driveshaft (Trans to Diff) angle. Also the shaft yoke looks to about 1-1.5" more exposed than previously. The Jeep was not previously lifted and I thought a 1/2 inch wouldn't do much (which turned into 6"+). I'm sure others have had this issue. What does eveyone else do about this? Thanks

shakle.jpg   driveshaft.jpg   setup.jpg  

Last edited by Plyj; 04-06-2013 at 07:44 AM.. Reason: clarification
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Unread 04-06-2013, 07:52 AM   #2
Anticanman
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Gotta post pics. I have a couple suspicions but wanna see your shackles first.
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Unread 04-07-2013, 08:21 AM   #3
Plyj
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Okay... photos added. Anything look odd?
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Unread 04-07-2013, 09:38 AM   #4
Anticanman
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First of all, you had a lift on there to begin with, just not in the springs. The shackles that you have installed in the pics give it a bit of lift too. How long are they from bolt to bolt? Second, you need a transfer case drop because you have at least 4" of lift from what I see in the pictures. Why 4"? The springs are at least 3" and the shackles (depending on length) look to this untrained eye as being at least 6" long.
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Unread 04-07-2013, 10:10 AM   #5
imstillatwork
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Why were you only expecting 1/2 inch lift?
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Unread 04-07-2013, 10:15 AM   #6
Plyj
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Great... thanks!
Shackles are 5" bolt to bolt (C-to-C). Ordered extended shocks (2' - 4" lift) so that I have some travel (not fully extended).

I had thought about removing the bottom leaf of each spring to see if that would bring it down some. It drives okay now, it's just the vibration thing that bothers me.

I'll look into the drop transfer case... never heard of it though it sounds like what I need to get less angle on the drive shaft.

Is the drop transfer case preferable to one of those multi U-joint shafts (@ $500) I've seen or do I need both?

Thanks...
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Unread 04-07-2013, 10:17 AM   #7
Plyj
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When I bought the shackles, they were advertised as 1/2" lift so I assumed that what I'd get??
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Unread 04-11-2013, 06:31 PM   #8
Plyj
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1990 YJ Wrangler 
 
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Location: Plymouth, MA
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Thank you! Thank you! Thank you!
Got all my parts in (extended shocks, drop transfer case spacers, etc. and bolted it all together (also went back to the stock 4" shackles) and this wonderful thing happened.
All the noise is gone, ride is fantastic, handling is superb (and I think I get better mileage as well... maybe not).

Anyway thanks for all the help. I love this Jeep!
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