brake calipers

My front calipers were ugly.  :(

I tried removing the pistons with compressed air and one moved.  Always the one on
the hose connection side.  This popped out that side leaving other one still stuck.
I finally found that the slot between the pistons wasn't for the rotor, it was so a wrench and brake pad could hold back the moving piston, and force the non mover out a little.
  The other side was oiled around the seal and pushed back into its bore.
This was repeated numerous times on one side.

The wrench method. I just got the bleeding pistons out- I'm not putting them back for a photo shoot.

 

Here is a close up of the chromed piston problems- The chroming becomes pitted, then the pits start eating up the seals and work rust into the caliper bores. Note the rust stain on the piston also..



Used pistons for sale...

Here is another problem with the brakes- lack of maintenance. In the caliper bore at the bottom Gunk from rust, contaminated fluid, deteriorating hoses, etc gather and can wedge between the piston to make it not move.  
  If you're rebuilding, there is a inner square rubber gasket and a metal collared rubber gasket towards the disk area that need to be removed, clean the mating surfaces and replaced.

Thankfully the bores are in great shape after a quick cleaning with a green scritchy pad. 

TIPS:  The bleeder valve goes directly to the non hose side bore to clean that out and apply air to that piston.   The 3/8" bolt goes directly to the hose side bore.