Brake sticks when hot

[jwilbur]

Looks like it is a hydrolic issue. I went for a flight and when I got back the brake was stuck as usual when it's hot. While hot I opened the bleeder valve. Fluid shot out and the brake immediately released. I've been in touch with George from Matco. This was his suggestion to help narrow down the problem.

Next, I'll get it hot again and start opening up other parts of the system to see what's not working correctly.

[BillL]

Originally Posted by jwilbur

Looks like it is a hydrolic issue. I went for a flight and when I got back the brake was stuck as usual when it's hot. While hot I opened the bleeder valve. Fluid shot out and the brake immediately released. I've been in touch with George from Matco. This was his suggestion to help narrow down the problem.

Next, I'll get it hot again and start opening up other parts of the system to see what's not working correctly.

This confirms that the bleed opening hole is not being uncovered. Just find out why. If your external springs are really allowing full return then it is internal, but this is definitely the issue. Good Luck, it can be fixed without changing vendors.

[jwilbur]

Finally getting back to this. The hydrolic problem appears to be in my passenger side right master cylinder. But it's weird. When the brake is sticking, I can manually pull on the pedal back out and it doesn't budge and no change. But if I pump the brake a few times, the pressure will release and the brake frees.

And today I went to drain the fluid from the right side. I opened the bleeder valve and pumped some air down through the reservoir. Nothing came out. I went into the airplane and pumped the right brake a few times. I heard fluid squirting out the bleeder valve into my container. I went back out and pumped air again and all the fluid drained.

It seems like the MC plugs up if it sits for a long time. Pump it once or twice and it opens to the reservoir. Should I just replace the MC? Or does this symptom point to something other than the MC?

[JonJay]

There should be a small amount of ?slop? when you release the peddle by pulling it back. If there isn?t, I could see a scenario of it being right on the ragged edge where the internal seal isn?t opening up the port unless you mess with it a bit. If that is the case, check the clevis/jamb nut adjustment and make sure the peddle was fabricated correctly and the throw allows for that slop. If it?s tight, there is a problem with the setup, not the MC.
If the slop is there, my guess is there is some kind of weird damage to the seal that could be fixed by rebuilding.
Just a guess.

[jwilbur]

In the end I replaced the calliper and brake-plate and pads. Turns out the calliper was badly warped. I also rebuilt the passenger side master cylinder. There was nothing obvious I could see wrong with the MC. I got it all back together today and went for a little flight.

All appears to be working correctly.

As always, I appreciate very much the input and advice and shared experiences offered on this forum.