Step 5: Cleaning/Prep: Use a small amount of brake parts cleaner on a clean cotton rag over the entire piston cylinder area, this may take a while, be meticulous. Do not use anything abrasive. Your pistons should look like this if they are not scarred or damaged. To further clean the pistons, use steel wool #0000 for surface rust or to polish them up. Before re-installation clean the pistons with some compressed air to remove any particulates.
The cylinders cleaned are shown below as well:
Step 6: Assembly: Coat the inner seal and caliper cylinder surface with brake fluid. Insert all 4 inner seals into the recessed cylinder channels.
Step 7: Lube the covers: Using the supplied kit grease packet cut a very small corner off the plastic packet so that only a small amount can be squeezed out at a time.
Apply a small amount of this grease to the pistons recessed channel where the dust cover connects to, get a nice consistent bead all the way around. The grease is just to be used on this lip surface of the cover where it contacts the piston, no where else during the entire assembly is it to be used.
Carefully stretch the new dust cover into the pistons recessed channel (make sure it is seated properly). The piston on the left is the correct way to set them up back into the caliper housing. The right piston in this pic is an illustration just showing that the dust cover is correctly installed and seated.