--Pulled from the DJM page--
"Pinion shims are most commonly used for hangers and shackles on full size trucks (Chevy, Ford and Dodge)."

They don't give an example for just shackles.

 

I'm glad someone is paying attention. When hangers and shackles are used to lower a truck, it will push the front of the nose of the diff upward. Therefore the shims would need to be placed in from the front (fat side towards engine).
When using just shackles "only", it will thrust the front nose of the diff downward. This leading to what this thread is all about. Therefore, the shims would need to be placed in from the rear (fat side towards rear).

Jim

 

oh shat, didn't even notive the words, I just assumed the left was front.

 

another amazing piece from yours truely

I don't know why this is difficult for you guys to understand, it's basic geometry...



That's what drop shackles AND drop hangers do to the pinion angle. The differential isn't rotated like it is with drop shackles ONLY, it's just raised up which puts the pinion at a different angle than stock. With hangers and shackles, the front of the differential needs to be rotated down to acheive the correct pinion angle.

****Again, I'm no expert, but it's basic fuggin' geometry

 

its only difficult because some peopel think one thing and others think another ha ha thanks for the time spent on your picture though

 

I'm telling you the way it is. Did you install your shackles?

 

no, i had my shackles installed about 2 years ago before i got into trying things myself. but i know its just shackles

 

Hellllo! Ok, I just got it. I guess my assumption is what is making me think about it incorrectly. I thought the shackle wouldn't change the angle of the pinion, but instead just "move" the diff closer to the bed, slightly changing the angle of the driveshaft relative to the diff pinion angle. In reality you guys are saying it tips the pinion downward. So I actually need to actually point my pinion upward at an even greater angle than my driveshaft? This seems to counteract what I'm reading here. Maybe my pinion was off to begin with? I'm getting the feeling the only way I'm going to be able to confirm all this is to put the stockers back on and see what it was then.

http://www.carcraft.com/howto/91758/

"According to Bickel, a ladder-bar suspension normally requires ˝ degree of pinion angle, a four-link requires 1-2˝ degrees, and a leaf-spring suspension requires up to 6 to 7 degrees. In all examples, we’re talking about negative pinion angle, i.e., the pinion is nose-down in relation to the driveshaft"

 

FORGET ABOUT THE ANGLE!!!

The differential is rotated as well as moved closer to the bed - since the drop shackles relocate only the REAR of the leaf spring(causing the diff rotation). You have to rotate the differential back the way if came if you want to solve anything - regardless of what the angle is, was or will be!!

 

Gosh I can't believe this has made it to 5 pages. Look at the first page people.