Barry - Forgot to ask about one of your posts above: What is the red rubber grease? And when you did an overhaul, did you completely rebuild? I've seen some kits, wasn't sure if it was a good idea to do at a particular interval or just if you start having problems.
I suspect Barry means something like PBR rubber grease. It is expensive and for the few times you would use it, you are better off using brake fluid as your assembly lube - bit messy but easily cleaned off with plain old water once the caliper is together.
If you are going to refurbish your own calipers the two things that seem to cause the most problems are:-
1/. Getting the old sealing ring out - They can be very difficult and you heve limited purchase to get to them. My solution is to lay the caliper halves out level in the back yard (with bleed nipple(s) fitted, then fill the caliper bore with Shelllite (Or Coleman Fuel for the US participants) followed by a match. After the fire goes out the seal will be mostly burnt out and the remains come out easily with the tool I am about to describe.
2/. Over time the combination of small amounts of escaped brake fluid, water and Dog knows what takes up residence behind the seal, when you do get the seal out there is frequently a nasty, lumpy residue remaining in the seal "alcove" which will prevent the new seal from seating correctly and in turn prevent the piston from going past the seal. I make a tool using a small screw driver whose blade width is a near as possible match to the width of the seal groove. I then bend the tip of the screwdriver 90 degrees so that I can use it as a scraper to clean the bottom of the seal groove. I find that after using fire to burn out the old seals that the "residue" comes out much more easily than it does otherwise. It is still however a long job, put aside about an hour for each caliper. be careful not to bear on the seal groove sides, you don't want to make them wider.....
