Yikes! Don't shave anything down! Something must be assembled wrong or misaligned!
Here a a couple of things to check:
1) Left front upright (driver's side front) should be part C1, Left rear upright (driver's side rear) should be part C2. The part number is on the inside of the arm that attaches to the steering linkage.
2) Double check bearing/bushing installation in the uprights and in the diff housing.
When I assembled mine, I had to look carefully to be sure I got parts C1 and C2 in the right locations! I even had to reinstall improperly installed ball connectors when I double checked things at this point!
Hope that helps... if not give us some more feedback/info on your problem...
Paul