So Ive got a shackle and hanger, with a spring clamp on the front of the overload. I had a vibration around 70 or 75 on up. I put in a 4 degree shim and it moved the vibration up to starting around 85 or 90. Should I put in a bigger shim? Im kind of wondering if its not the pinion angle causing it but the shim changing it makes me think that is the problem.

 

I have 8 degrees of shim in mine to get the vibration to go away.
You need to check what the truck sits at.
There is a tool i forget the name to check what kinda degrees your pinion angle sits at.
Find out what it's at with no weight in the bed and then try to get it right.
Normally you want a -3/-4 degree pinion angle that way when you floor it it goes up to dead zero and no more vibration.

 

Cool, Im gunna get a bigger shim then. Mines still a little positive.

Mine doesnt have to be floored though to vibrate, just cruising at 85+ has a pretty bad vibration.

 

How far positive is it? It should be slightly down looking when your under the truck looking straight at it.
If it's just as cruise then it's gotta be way off or something else cause i never had any problems unless under heavy throttle....

 

Not much.

Yea I dunno, Im gunna check some other **** out too and see if I can get this figured out.

 

Well the vibration goes away just past 100.