Topic: Hydro Brake Question

[jakec]

If I release the bleed screw can I push the piston further into the caliper?

I'm having an interesting problem where my piston isn't retracting and I want to experiment without taking it apart.

[scottly]

You can push the piston back in with the bleeder closed, as long as the tiny hole in the master cylinder is clear. It won't move very quickly, though.

[jakec]

This is a fresh build with all new everything including piston, seal, lines, etc. And it's dragging. So I was going to see if I can push the piston back in and try to bleed it some more

[bryanj]

Did you clean the seal groove out perfectly, including the corners?

[newday777]

This is a fresh build with all new everything including piston, seal, lines, etc. And it's dragging. So I was going to see if I can push the piston back in and try to bleed it some more

Did you only rebuild the caliper??
If so, the problem is the master cylinder return port is plugged. You'll need to dig into rebuild of it and clear the return port of the hardened gunk, use a wire from a wire brush and needle nose pliers.

[jakec]

I did clean the groove, like my life depended on it. But I do agree that the symptoms sounds like a dirty groove or bad seal.

Also the return port seems to be working as it send a bubble/shockwave through the fluid while I  bleed it.

I am using a speed bleeder that make the process go much faster, maybe I just need to bleed more?

[aircraftgrade]

If it helps at all, I have a front caliper that has not been rebuilt, but I did disassemble it to grease the pins and make sure everything worked.

Anyways, to retract the pistons to reinstall the caliper I had to squeeze pretty hard on the brake pad with a pair of channel-locks. They retract slowly. I did one side at a time, first the piston farthest away from the brake line, then the one closer. Otherwise, you might pop the other piston out by squeezing the closer one first...

Good luck!