How to Grease Ball Joints with or without a Zerk .
1) The process of tapping a ball joint could result in metal shavings working their way between the ball and the bearing surface, or the surface of the ball itself could be damaged. 2) Since most ball joints without a zerk fitting are designed as a sealed bearing, grease pumped into the joint likely does not have a place to go meaning you may not get much lubricant where you want it to go.