Not easy to change. Had to get the shaft in a good position. Most wrenches would not be able to get the right angle on the zerk. By using a combination of wrench and needle nose pliers was able to get it loose enough to take out with fingers. Worst part is I had the different zerks in several times before I knew the one I had would not work. Finally gave up on those and researched where to find a zerk in between 45 & 90 degree and found the 67 degree, it makes getting the grease gun on the zerk a straight shot.
you may need to adjust it wears they are not self adjusting like on a car. theres a bolt and locknut on that center caliper.
With the parking brake released, loosen the locknut and tighten the bolt with your fingers till sung, then back off a turn, and tighten the locknut. Check that the parking brake pedal doesnt bottom out, and you dont get any squealing when driving or you may need to re-adjust.