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Unread 03-24-2013, 09:43 AM   #16
bhansen99xj
Registered User
1999 XJ Cherokee 
 
Join Date: Apr 2009
Location: Beloit, WI
Posts: 51
I was going to say... My old 3" springs had no issue but as you can see in that pic there is a slight angle to that block. I would imagine there is a tolerance range to the angles. I'm sure an SYE would fix some problems but wouldn't I get the same effect with shims? It's all about angle correction, right? Please, correct me if I'm wrong.

Even with the tapered lift block evidence, I still can't wrap my head around why I'd be getting the vibes.

I really dig the dialogue, guys!

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Unread 03-24-2013, 11:02 AM   #17
cbenez1
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1991 XJ Cherokee 
 
Join Date: Jun 2009
Location: Bucks County, PA
Posts: 1,611
Quote:
Originally Posted by bhansen99xj View Post
I was going to say... My old 3" springs had no issue but as you can see in that pic there is a slight angle to that block. I would imagine there is a tolerance range to the angles. I'm sure an SYE would fix some problems but wouldn't I get the same effect with shims? It's all about angle correction, right? Please, correct me if I'm wrong.

Even with the tapered lift block evidence, I still can't wrap my head around why I'd be getting the vibes.

I really dig the dialogue, guys!
An SYE is the way to go and(especially if you plan on going higher in the future) would definitely cure it but that is a more involved and expensive solution. The shims are cheaper and easier but they will only do so much They all (XJ's) react differently to angle changes. My 91 is at 5.5/6 inch lift in the rear and has no issues with out an SYE. But I did change the pinion angle when I installed an 8.8 ford diff/1 inch t-case drop and its a manual trans. For whatever reason the manuals seem to be a bit more tolerant with driveshaft angles. Having said all that if I go any higher with the 91 I will definitely need an SYE. I just did bastard pack rear springs in my 2001 XJ last week for a about a 4 inch gain. This combo had a little noise/vibe when I test drove it. I then added 4 degree shims to the pack which took the noise away almost 100%. I figure a 1 inch t-case drop will take care of it completely so I'l be making and installing one this week. I know this alot read but hope it helps.
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A nation that "forgets" it's defenders, Will itself be "forgotten". Semper fi
91 XJ 4.0 5spd 5.5 on 32's, flat flares, sand camo'd. "Battle Wagon"
01 XJ 'Up Country' 3.5 on 29's former fire vehicle. Bright red. "Fire Wagon"
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Unread 03-24-2013, 11:16 AM   #18
bhansen99xj
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1999 XJ Cherokee 
 
Join Date: Apr 2009
Location: Beloit, WI
Posts: 51
Quote:
Originally Posted by cbenez1 View Post

An SYE is the way to go and(especially if you plan on going higher in the future) would definitely cure it but that is a more involved and expensive solution. The shims are cheaper and easier but they will only do so much They all (XJ's) react differently to angle changes. My 91 is at 5.5/6 inch lift in the rear and has no issues with out an SYE. But I did change the pinion angle when I installed an 8.8 ford diff/1 inch t-case drop and its a manual trans. For whatever reason the manuals seem to be a bit more tolerant with driveshaft angles. Having said all that if I go any higher with the 91 I will definitely need an SYE. I just did bastard pack rear springs in my 2001 XJ last week for a about a 4 inch gain. This combo had a little noise/vibe when I test drove it. I then added 4 degree shims to the pack which took the noise away almost 100%. I figure a 1 inch t-case drop will take care of it completely so I'l be making and installing one this week. I know this alot read but hope it helps.
No this is perfect. After all the discussion on what could cure the problem, I see the options so pros and cons is where I am at right now.

I am at a 3" lift right now and that is as high as I want to go. I am thinking shims is the way to go.
I've seen 2, 4, and 6 degree shims. Which angle is the one I am correcting so I know which to get?
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Unread 03-24-2013, 11:28 AM   #19
cbenez1
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1991 XJ Cherokee 
 
Join Date: Jun 2009
Location: Bucks County, PA
Posts: 1,611
I'm thinking 4. Reason being you had no vibes with old sagging lift and with the new springs you probably only gained an inch so it can't be to far off.
__________________
A nation that "forgets" it's defenders, Will itself be "forgotten". Semper fi
91 XJ 4.0 5spd 5.5 on 32's, flat flares, sand camo'd. "Battle Wagon"
01 XJ 'Up Country' 3.5 on 29's former fire vehicle. Bright red. "Fire Wagon"
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Unread 03-24-2013, 07:25 PM   #20
sAe23
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1995 XJ Cherokee 
 
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Location: Los Angeles / SFV, California
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Quote:
Originally Posted by sAe23 View Post
If you don't have a SYE, the pinion and T-case output need to be parallel.
Get a cheap angle finder and MEASURE your setup before installing shims...
Quote:
Originally Posted by bhansen99xj View Post
[snip]
I've seen 2, 4, and 6 degree shims. Which angle is the one I am correcting so I know which to get?
You are adjusting the axles pinion angle, but you should also measure the T-case output:
http://www.4crawler.com/4x4/CheapTri...l#Measurements
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Unread 03-31-2013, 11:12 AM   #21
bhansen99xj
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1999 XJ Cherokee 
 
Join Date: Apr 2009
Location: Beloit, WI
Posts: 51
Quote:
Originally Posted by sAe23 View Post

You are adjusting the axles pinion angle, but you should also measure the T-case output:
http://www.4crawler.com/4x4/CheapTri...l#Measurements
THIS! I've been reading this multiple times. Thanks! I haven't done anything yet. The description in the article definitely fits with the vibes at high speeds, changing pitch with speed. Will be investigating further.
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