I've used silver nickel antiseize on marine trailers - this is just down to the immersion issue and rubber grease going as solid as hell. Not sure what's in copper antiseize but the silver nickel seems fine and hasn't swollen the rubber that the trailer calipers run with. On everything else I'm using rubber grease and no issues as per (for what that's worth).
As far as the 2009 Escudo - is that a manual park brake or electric switch? Is it combined disc/drum rear brakes (service brakes are disc and caliper with a drum setup for the park brake completely separate) or combined drum - or combined disc with a separate actuator? If it's combined drum with manual hand brake and the shoes are worn you should note the number of clicks on the handbrake lever increasing. If it's a different style this test won't help.
My experience with seized calipers, if they are fully seized normally the brakes get more firm not less as there is less slack in the system for the hydraulic fluid to take up. What you are describing would seem to be either a mechanical issue with a seal or cup worn somewhere that is allowing pressure to be lost, a vacuum booster issue or impending failure of a flexible component like a hose. Possibly a combination of the lot, with worn brakes pads as something else to check. Effectively with hydraulic systems, if you are increasing the volume that the system is trying to push hydraulic fluid into, the result is a spongy feeling pedal - the cause could either be wear somewhere, losses in the system due to something not working correctly or for some reason something has started to compress that shouldn't. Chuck the thing up on stands or blocks and pop the wheels off, and get someone to cycle the brakes while looking at each brake assembly on the corners. If everything looks good, then it's probably the actuating system...
Bookmarks