2020 Custom Crew Cab drop shackles-rear end vibration after install, no factory shim on truck

[jtlans]

Good afternoon,

 

I had 1.5" drop shackles installed on my 2020 Custom crew cab 4WD.  On the first drive, I noticed a rear end vibration when accelerating and decelerating from 20 mph to 30 mph.  I took it back this morning and had the shackles moved to the 1" drop point.  The same vibration remains.  I took it back again and went under the truck with the technician look for the shim that needs to be rotated to remedy this vibration.  On my truck, there was no shim present.  Has anyone else encountered similar?

 

Thanks in advance!

[mafd2]

3 minutes ago, jtlans said:

Good afternoon,

 

I had 1.5" drop shackles installed on my 2020 Custom crew cab 4WD.  On the first drive, I noticed a rear end vibration when accelerating and decelerating from 20 mph to 30 mph.  I took it back this morning and had the shackles moved to the 1" drop point.  The same vibration remains.  I took it back again and went under the truck with the technician look for the shim that needs to be rotated to remedy this vibration.  On my truck, there was no shim present.  Has anyone else encountered similar?

 

Thanks in advance!

The 4x4 may not have the shim. Seems I may have seen that on a thread. I'll try to find it.  Reversing the pinion shim does stops the vibration. They do sell pinion shims. 

[tuckin22]

This ever get figured out? Having the same issue on mine. I ordered some shims but am worried about the center pin not sticking out far enough.