partial hanging brake left side only

[Paul Klouda]

Any suggestions on a brake that is giving me fits. Rebuild the master cylinder and when installed the brake does not hold. It bleeds properly then seems to release and go to the floor. When it does work unless you press the bottom of the pedal the brake does not fully release and grabs slightly. we have had the cylinder out 3 times and checked for proper rebuild seems to be OK. Next step seems to be replacing cylinder. The right brake works fine. I'm open to any suggestions its got us baffled at the moment.

Thanks in advance....

[Don Oltman]

It kind've sounds like there is still air in the system. How have you been bleeding the brakes?
Don

[Paul Klouda]

We pumped the peddles then held them down and cracked the bleeder valve. Shut the valve and repeated making sure to add fluid to the reservoir. Even disconnected the right brake capped the lines and tried just the left side with no success. Not sure what to do next, the brake will build pressure then if high pressure applied to peddle it drops to the stop and then you can pump it up again. No leaks anywhere.

Any suggestions on where to find a rebuilt or core master cycliner? Will be calling Webco Monday...

[MULEFLY]

We (Heritage Aero and I) fought this like crazy last spring. I was getting less than 10 landings on a set of brakes due to drag. It seems better, but we went thru an extended number of items... perhaps the moon is in a different phase -- I'm keeping my fingers crossed as it for now is no longer a problem.

Found items. The torque plates were deformed... the pins were not parallel and contributed to hang up. Replaced torque plates. Be certain that you are not putting more than 65 inch pounds of torque on the mounting screws for the brakes on the plates (Yes that is inch pounds not foot pounds). Cleveland has a description of this very specific problem in some of their technical materials and when we called them, it was the first thing that they recommended. We changed calipers... as the deformation in the torque plates had seemed to cause some deformation in the calipers as well.

In the end, I think that there was also a bad batch of rotors out there that we kept getting from the same distributor. After chasing all of the above and going thru 4 sets of brand R.... we installed Clevenlands and have been happy with the results.

It can be maddening!
Jim

[Don Oltman]

I thought maybe that's what you were doing. Others may correct me here but I don't think it is possible to bleed Comanche brakes by pumping. It either requires a pressure pot or an alternate way that you can do yourself inexpensively. If you have a old time pump oil can put a 5 dollar bill in your pocket and head to Home Depot. Buy a Teflon threaded bolt the same size as your caliper bleed screw, a Teflon nut for the bolt and 6 feet of plastic tubing that will fit over the bolt tightly. Cut off the head and drill a tiny hole down the middle of the bolt. Screw the nut halfway down, put a little O-ring in front of the nut, attach 2 feet of the hose to one end and the oil can to the other end filled with 5606. The other 4 feet of hose is for the overflow from the reservior back down to the can of 5606. Attach to bleeder screw hole and pump until no bubbles come out of the line leaving the reservoir. Replace bleeder screw and move to other side. No more soft pedal.

Don

[N3322G]

Wish I watched at annual when they were doing this part - each of Clifton guys have somethings they do better than others and Albert got the bleeding the brakes job. They came out perfectly.

Jim, thanks for sharing - I thought I was the only one who got 'lucky' with stuff like you described.

[Paul Klouda]

Thanks for the input everyone. We pulled the calipers and replaced the o rings checked the plates and found no problems. The pads are not wearing uneven and it seems the parking prake portion of the master cylinder is suspect. Anyone ever replace the master cylinder? If so did that solve the issues? I can be available by phone if someone is willing... it may be better to talk directly... let me know my cell 740 260 3950 Ohio time. thanks again!

[Gary Mcfarlin]

I had some issues last year with the left brake dragging significantly at times on my PA-30, especially noticeable when towing in or out of the hangar. After checking for stuck pistons in the caliper and finding nothing wrong, went to master cylinder. Eventually found the 45 fitting on the bottom outlet of the left master cylinder had rotated down slightly which caused that hose to hang on the aircraft structure and keep the master cylinder from completely bottoming out and releasing all of the pressure. Haven't seen a recurrence of the problem in 8 monthssince correcting the alignment of that fitting and hose.

[Ron Davis]

Hope this drawing helps. Talked to engineer last year and he says parts are still available. You may talk Bob Weber out of spare and send yours to him to find problem. Spruce is a dealer but they need the right part numbers from this drawing if you want to try again. I blew out a tire as my adjustment for hand brake did not fully release my right side brake. That side does not release at the exact same angle as the left one on my airplane. Also I had to add to check list for our models: Assure parking brake handle all the way in before landing. Ron

[Paul Klouda]

Thanks for the drawing Ron!

This issue has been giving me fits for better part of a year. The hanging is one issue, the leaking fluid (on my left shoe) and soft peddle is of more concern. I found that when you tap the rudder peddles (bottom only) just before taxiing or when we push into the hanger the brakes do not hang. I will check the lines to and from to see if they are binding on the frame near the firewall per another suggestion.

I guess it boils down not wanting to shell out 1500+ bucks for a new cylinder from Spruce! Hopefully we will get to the bottom of this soon!

Maybe we will meet at the CPPP in April at KPOV (Portage, Ohio) I'm hoping to attend the ground school at least! I have been in and out of there many times over the years nice airport!

Regards and keep the shiny side up!

Paul

[md11flyer]

Paul:
I am no expert on hoses used for aircraft brakes... never cut one open and don't know whether they can deteriorate inside like automotive
flexible rubber brake lines.
The reason I am bringing this to the equation here is, your sticky brake sounds exactly like my front brake on my Dodge Caravan. I put new calipers on the
car when they started sticking... didn't help, and since it was only one wheel, reasoning said it then had to be the hose. Indeed the new hose fixed the problem.
I cut the old hose open and the inner rubber hose had ruptured and the flap produced by this ruprure caused a restriction for the fluid returning to the master cylinder. The brake otherwise did
its job as the braking pressure easily passed by the restriction. The auto brakes flex lines have an inner hose, a reinforcing type cover over that and an outer hose.

If your brake hoses are old you might want to check if new ones will help.

Good Luck.

Gary

[Paul Klouda]

Thanks Gary,

We did replace the lower hose with a new one (the line leading to the wheel) with no success. That was our thinking as my A/P recalled another situation with the lining in the hose creating a "flap" valve not letting the fluid flow properly thus causing a brake issue.

Still mucking through this one...

Regards,

Paul