Rear brake mystery, Help!

[Gullymonster]

Have '93 75 brick for second season now, and noticed it was time to replace rear brake (pad non-existant) I was also leaking from pedal side of master cylinder (boot), so that replacement came shortly after pads. But here was my process

Ordered pads, and decided to renew o-rings and seals in rear caliper. Noticed a loss in pressure to brakes, so I renewed master cylinder piston. Bled brakes from caliper and reservoir side. rode for a 100 miles and repeated bleed.

My issue is i've noticed the pads weren't retracting from rotor completely so as I spin wheel i heard almost metalic squealing caused by outboard pad rubbing on rotor.

I can fix this by pushing the pad away from rotor with finger or screw driver- but then I lose pressure to pedal until a few pumps where pressure returns and the pad sticks again slightly rubbing rotor, causing rotor to get super super hot from any riding let alone at highway speeds.

I've disassembled, and cleaned piston cups, and re assembled, bled and re-bled, and I can't figure out a solution to this. All insight is appreciated, especially as I will probably be renewing front caliper components similarly within the next 1000miles.
Thanks

[Scott_]

Double check the free play at the foot pedal, if that does get messed up, it can cause the pads to "ride" the disk more had has caused fires of the paralever rubber boot at the final drive.

[johnny]

greetings gullymonster...

sometimes when the master cylinder piston is replaced and there is no pressure on the peddle from bleeding yet... the peddle will go down farther than normal pushing the piston back farther than normal... if so... the piston maybe stuck or have limited movement causing a soft peddle bleeding and caliper oddities...

when bleeding brakes after a master rebuild or caliper rebuild its recommended not to take the lever or peddle all the way until its full and can take the pressure...

dont know if its relevant... just wanted to put it out there for consideration...

j o

[Inge K.]

At the inside of the MC bore you got two small holes where the fluid enters.
One of them is real thiny....if that got filled with crud you would get similar symptoms
as the piston not fully returning.

[Oliver]

Im on with them, there may be some crud in the cylinder or you may need to replace it because the inside may be pitted, also adjusting the lever can cause it to push to hard when not engaged, causing high heat and can even set a paralever boot on fire. Check all of those things. A small bit of pad to rotor touching is normal.