We strongly recommend using #106210 HUDY Graphite Grease for the drive shaft coupling, especially for the front drive shafts. When the coupling is not greased it may cause wheel vibration when full steering is used.
Therefore it is very important to grease the couplings very often in order to remove wheel vibrations.
When building the drive shafts, start by greasing the coupling and inserting it into the shaft as shown.
Then install pin into the drive axle in order to connect the drive axle to the shaft.
It is very important to use thread lock for the hex screw, otherwise the screw may unscrew. Use only a small amount of medium-grade (blue) thread lock on the screw.
After applying threadlock to the screw, install the screw as shown. Remove any excess threadlock.
Source : XRAY