My disc brake is dragging.

[Jim]

Btw, the name.... "compensating" or "compensator" port.....

As the pads wear, the caliper piston(s) have to push further in toward the disc to make up for the lost pad thickness. So more fluid needs to be in the caliper as the pads wear, while still allowing the same pedal/handle "feel." In other words, it "compensates" for pad wear to give the same feel no matter how worn the pads are.
The return spring is what pulls fluid back to the M/C to prevent dragging brakes. There's your "relief"... no matter what Harley calls it.

 

[Kevin Werner]

You can see my port, it is clear and I can see the piston move behind it. Ther is the possibility that my roadside quick bleed did release some air. I did not have a clear hose and some bubbles could have been part of the "ooze" that I released. It was not a splatter or fluid and air, it was 95 degrees and 90% humidity that day, and I was nursing my baby Red Bike.

 

[gggGary]

the name.... "compensating" or "compensator" port.....

Whew, THAT'S a relief!

 

[Jim]

Whew, THAT'S a relief!

You can take the teacher out of the classroom, but you can't.....

 

[gggGary]

You probably wouldn't guess I was that smart ass in the back of the classroom making the teacher's life miserable................

 

[gggGary]

Well if both ports are free, then it's time to demount the caliper and push the piston back, see what goes on, it shouldn't much more than firm thumb pressure to send fluid back up, out through the replenishing port. If that doesn't go smoothly then it needs to come apart again. Also check that the slide bushing/seal on the caliper mounting bolt allows the caliper to push in and out smoothly on the fork mount.

 

[gggGary]

I've seen old rubber lines collapse internally and block a caliper from returning, Would be rare but possible I guess there's something in your new teflon brake line that's causing a blockage.
Lets see the brake handle/ adjuster too.
You've got new paint, be super careful about a stream of brake fluid squirting out of that port...................

 

[Jim]

Ther is the possibility that my roadside quick bleed did release some air.

The compensating port should have allowed any air to release without building any pressure. If pressure built up downstream, the compensator port was (is) plugged or the piston spring isn't pushing the piston all the way back to un-port (relieve) the compensator port.
Like Gary sez, pull the caliper and push the piston in. As you push, fluid should squirt out the compensator port... a lot.

 

[Kevin Werner]

The compensating port should have allowed any air to release without building any pressure. If pressure built up downstream, the compensator port was (is) plugged or the piston spring isn't pushing the piston all the way back to un-port (relieve) the compensator port.
Like Gary sez, pull the caliper and push the piston in. As you push, fluid should squirt out the compensator port... a lot.

Draping the fender and taking the tank off tomorrow...

 

[Vincenthdfan]

Just went through this on both my 1980's, finally gave up and changed/rebuilt everything...just test rode the second one tonight in fact.

New caliper pistons, seals, master cylinder kits and hoses...both bikes work like champs now and far less frustrating than trying to limp through making the old components work.

 

[AUTOMAN]

Seal on caliper pushes piston back a couple thou away from the rotor.
Or should.

cliff