Recently had installed a set of Western Chassis 2" drop shackles by our alignment shop. Install went ok, but now I'm getting a vibration or whirling noise when the speedo hit between 60-75 mph. Anyone had this problem? Any easy fixes? (other than not driving 60-75)

thanks

 

It sounds like you may need to install a pinion shim under your leaf springs to correct the increased angle of the driveshaft to the pumpkin. These can be bought from AIM or a like suspension company. My .02

 

See our posts under the Supercrew forum regarding drop and vibration