AO Platinum Member
Join Date: Feb 2002
Location: The land that Time forgot
I presume you gave the sliding pins a bit of a clean up (emery paper) to remove the old crud and any corrosion before re-fitting them?
As a tip - use high melting point (LM) grease rather than Copaslip. Copaslip is good on the back of the pad where it touches the piston but it's more of a dry lubricant and so not so suited to the pins.
Anyhow, the caliper body should move easily in and out of its frame. If it's stiff or sticky, clean the pins some more.
Did you file the edges of the pad backing plates slightly? You get grease and crud build up in the caliper tracks so that a pad plate can "jam" in the caliper. They ought to not have any play.. but they also have to be able to move as the pads wear. Put a tiny but of copaslip in the tracks where the pads sit, to keep the bare metal there from rusting.
I presume the caliper piston is not seized? If you wind it in a few turns (though they don't actually wind in.. but using a caliper tool keeps them straight) then does it move out again freely when you pump the pedal?
If all that checks out, then it could be that the hose is disintegrating internally. A flake of the hose inner lining may be flapping loose .. The fluid can squeeze past the obstruction when you're pressing the brake pedal but when you release it, the loose flap of liner will essentially behave as a valve, stopping the fluid from easily flowing backwards.
If you still have OE rubber hoses.. stick a new one on there and job done.
No bullets for Chaingun..