[Kitsch]

Hi all,

Nasty issue that's been preventing me from riding -

Initial issue - front clamps occasionally lock up, loosening the bleed nipple helps.

• Rebuilt caliper with parts from brakemasters, including new pistons and new seals, still locks up occasionally.
• replaced brake hose with NOS brakehose from Japan - still locks up
• the previous owner just replaced the reservoir so that's also new.

Current situation: the brake is dragging - front wheel cannot complete one revolution when spin by hand and lifted off the ground.

suspected issue: master cylinder act in a "check valve" fashion, because when I took the caliper off, and try to press the pistons back it won't buldge, even with a C-clamp.
The Caliper even made a dent on my brand new C-Clamp without the piston ever retreating (caliper not bled).

Photos show how hard the C-clamp worked...

But before I rebuild the entire master cylinder....I wanted to get a second opinion on what this could potentially be - to avoid making the previous mistake of rebuilding the front caliper at least 3 times without zero in on the problems first....

Appreciate any help!

 

[reclinedrelic]

The most likely cause is that the return hole in the master cylinder is blocked. For example see this old thread Clearing Master Cylinder Return Hole

 

[Cats]

I would also be checking the new pistons and seals to see if they are a true fit.

 

[danroy323]

I’m with Mike, it is most likely the master cylinder return hole. Sometimes brake lines can delaminate inside preventing fluid to return to the master but you changed to new lines.

 

[Sidecar Bob]

Yep. Classic symptom of a blocked return hole.