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Discussion Starter #1
Hey gang,

Just installed:
2" Beltech Lowering Hangers, 2' Beltech Lowering Shackles, and 6 degree Pinion Shims on an '04 Lightning with stock leafs
536655
. I'm getting a slight vibration with low pitch humming (wah-wah-wah) form 15-20mph (loudest @20mpg). The pinion angle now sits at 0 degrees (the pinion positioned horizontal now). Will replacing the 6 deg shim with an 8 deg get me where I have to be?
Recap from an earlier search:

"-3.9* is factory
-1 to -5* is acceptable
-1* is good for DD'ing
-2* is good for racing."

With the above info, I'm guessing an 8 deg shim will get me a -2 deg pinion angle. What do you all think? Online, I saw some 8 degree steel shims that bolt directly to the leaf centerpin. Thanks.
 

Pilsung
Joined
341 Posts
Hey gang,

Just installed:
2" Beltech Lowering Hangers, 2' Beltech Lowering Shackles, and 6 degree Pinion Shims on an '04 Lightning with stock leafs View attachment 536655 . I'm getting a slight vibration with low pitch humming (wah-wah-wah) form 15-20mph (loudest @20mpg). The pinion angle now sits at 0 degrees (the pinion positioned horizontal now). Will replacing the 6 deg shim with an 8 deg get me where I have to be?
Recap from an earlier search:

"-3.9* is factory
-1 to -5* is acceptable
-1* is good for DD'ing
-2* is good for racing."

With the above info, I'm guessing an 8 deg shim will get me a -2 deg pinion angle. What do you all think? Online, I saw some 8 degree steel shims that bolt directly to the leaf centerpin. Thanks.
How are you measuring? You have the right concept though. You want to rotate the axle down 1-2*
8* seems right if 6* is achieving 0*
 

2.9 Whipple E85R A1 Transmission
Joined
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Which way did you install the shim? Fat end towards the rear, cause it should be towards the front.
If it's that bad, might be time to relocate the perches.
 

Registered
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Discussion Starter #5 (Edited)
Here's how I measured the pinion angle.

1. Just so I could slide under the truck, I raised the rear up and then rested the axle on two jackstands. That way the full weight of the truck is supported by the suspension.
2. Using a digital level, I placed it flat against the driveshaft and took a reading.
3. Then I placed the same level flat against the flange of the pinion-diff. (I turned the wheels until I got as much surface of the flange as possible.)
4. The difference between the DS angle and Pinion flange angle is the the pinion angle.
In other words,

DS angle - Pinion Flange Angle = Pinion Angle

from what I got,
1.7 - 1.6 = 0.1 deg or 0 deg

the photo apparently shows there's not much difference between the DS and the Pinion so yeah, zero deg.


...and Yes, the thick or fat end of the 6 degree pinion shim is facing the front of the truck.

Beltech supplied the 6 degree shim with the spindle/hanger/shackle kit I bought from Jegs, but although the shim helped, it didn't seem it was enough.

If the 8 degree shim fails then yeah maybe I should get the perches rewelded (but who can do that for me??)
 

Pilsung
Joined
341 Posts
You need to measure with the vehicle at ride height. You can place some blocks of wood if your truck is too low to crawl under.
Measure from the driver鈥檚 side.
I see you subtracted the DS - pinion?
You need to subtract pinion angle from driveshaft angle to get TRUE pinion angle. (Readings taken from driver side)
On the driveshaft anything to the left of 0 is positive, on the rear end anything to the right of 0 is negative.
You will get some different readings from driver side with the vehicle at ride height and also by subtracting pinion angle from the DS.
 

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Discussion Starter #7
You need to measure with the vehicle at ride height. You can place some blocks of wood if your truck is too low to crawl under.
Measure from the driver鈥檚 side.
I see you subtracted the DS - pinion?
You need to subtract pinion angle from driveshaft angle to get TRUE pinion angle. (Readings taken from driver side)
On the driveshaft anything to the left of 0 is positive, on the rear end anything to the right of 0 is negative.
You will get some different readings from driver side with the vehicle at ride height and also by subtracting pinion angle from the DS.
Thanks for the feedback.

DS Angle =1.7
Pinion Flange=1.6

Whether or I subract one from the other or vise versa, the answer is still zero.

1.7 - 1.6 = 0 or 1.6 - 1.7 = 0

I thought it didn't matter what side (driver or passenger) you measured it from because I put the digital level directly underneath the middle of the drive shaft and then using he surface of the pinion flange for the other measurement.

I'll post pics up later to clarify.
 
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