This. The grease has to go between the bar and the bushing, so just drilling through the bracket wouldn’t help. Unless it’s a split bushing and the zerk lined up with the split. But even then I would bet that if the bracket was tight enough you would force grease out before your forced it through.
I like having the ability to grease all my polyurethane bushings. Poly is not like rubber, the bar spins in the bushing and that creates friction, and therefore the need for grease. With a rubber bushing there’s usually no movement between the surface of the rubber and the bar, the rubber twists with the bar and the movement is taken up with flex in the bushing rather than sliding on the surface.
I would drill through the bushing and line that hole up with the zerk. Some of the higher end poly bushings are designed with channels built in for grease to travel, you’re just replicating that.
