"Spongy" brakes.

[Guitarmaster]

Ok, I'm sure you guys are getting tired of hearing from me, but I love the information I glean from automotive and now aircraft forums.

The brakes definitely are "weak." Although I would not want to, I doubt I could lock them up if I had to. Think Piper Cub.

To me, a long time gear head, they feel like they need to be bled. They feel spongy and weak.

I have also heard glazed pads will do much the same thing.

I don't tend to need the brakes much, but it would be nice if I do need them.

Thoughts?

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[jetdriven]

I have been fooling with soft brakes for two years. Ours are acceptable but it would be hard to lock them up and the pedals travel too far. Paramount master cylinders have the port drilled in the side of the cylinder, IE unless you turn the MC sideways where the port is on the top it will be very difficult to get the air out of the MC. I have heard that putting the tail on the ground while bleeding helps with this. I switched to Cleveland MC when I installed the dual brake kit. Cleveland's have a rotable bushing which you can clock to the top of the MC as installed. The copilot brakes are super while the pilot side are soft. Next up is to replace the o-rings in the parking brake valve as I think it can be admitting air into the inlets of the pilot side MC's. Another tip on bleeding, do it at a moderate rate with a good bleeder. Ours at the shop is not a good design and it traps air which goes into the system. N601RX has a bug sprayer adapted to be a brake bleeder and he had excellent results.

[N601RX]

Here is the $7 sprayer from Lowes that I used.  It works well on the flaps also.  I've found that you need a second person to work the pedals back and fourth. Bleeding is messy and not really all that much fun, so if you have any leaks or need hoses or seals replaced do all of it at once.

[Marauder]

 Bleeding is messy and not really all that much fun, so if you have any leaks or need hoses or seals replaced do all of it at once.

 

Not to mention if you have the brake reservoir on the inside of the firewall...

[N601RX]

I have a piece of plastic hose with fitting that I screw into the reservoir and run it down to the floor into a clean container.

[N601RX]

There are some pictures I posted on the link below that shows the internals of the Gerdes/Cleveland master cylinders. These cylinders use a Stato-seal between the piston and shaft.  The piston is spring loaded and slides back and fourth on the shaft. You must get the piston to back away from the Stato-Seal before you can get fluid to flow backwards through the system.  Higher pressure will make this more difficult as it will keep it pressed up tightly against it. Try a low pressure and have someone work the pedels back and forth.  This will unseat the seal and let oil flow in reverse through the system.

 

http://mooneyspace.com/topic/4574-bleeding-brakes/page-2

[63C]

I just did mine by myself with a simple oil "squirt" can from each wheel starting with the passenger side. I hung a hose over to the floor from the reservoir to a clean jar so I could watch my progress. Was done in about 15 minutes and brakes are firm. I just installed new hoses so the system was pretty much empty. I just kept pumping until I had filled the quart jar over 1/2 full to hopefully chase any pockets of old fluid out. This old 63 C system may be totally different than what you are dealing with.

[Mooneymite]

I don't know if this works on all models, but each annual, I (er, I mean the AI) drain(s) a bit of brake fluid out of the caliphers. Usually the first little bit is dark and thick.

Then just top off the reservoir.

[carusoam]

GM,

You are a solution to a known challenge. Many here are a wealth of Mooney knowledge in search of someone to share it with...

You probably want to search first, then ask the tough ones...

Every now and then, something changes, or something new comes along...

Then share your experience with the next person...

As someone here often says, fly it forward...

Best regards,

-a-

Definitely check the age of the return hoses, they get old and crack. Properly drain out the old fluid and replace with new. Avoid air getting in the system, it is a real challenge to get back out. Don't overfill or it ends up on the rug(interior firewall mount of course).

[orionflt]

I don't know if this works on all models, but each annual, I (er, I mean the AI) drain(s) a bit of brake fluid out of the caliphers. Usually the first little bit is dark and thick.

Then just top off the reservoir.

Servicing the brakes is legal under owner performed maintenance, and as for the Annual inspection, the person that does all the work opening the plane does not have to be an IA or even an A&P as long as the IA is supervising and performing the actual inspection (looking at all the required areas as specified by the manufacturer and the FARs).

 

Brian 

[jetdriven]

The IA actually must do the annual inspection. An A&P may do the repairs. But he cannot delegate the inspection.

[N201MKTurbo]

The IA actually must do the annual inspection. An A&P may do the repairs. But he cannot delegate the inspection.

True enough, but the IA doesn't have to touch one wrench or sign off the work of the A&P. The A&P can return the plane to service after he does the work the inspector specified.

[jetdriven]

No, but the IA must actually do the inspection. This doesn't mean he has to undo one screw, but he must physically inspect the aircraft and sign the logs.

[Guest]

Never tired of reading the questions and the many informed answers. Fire away!

Clarence

[orionflt]

I do believe that is what I said

[Mooneymite]

True enough, but the IA doesn't have to touch one wrench or sign off the work of the A&P. The A&P can return the plane to service after he does the work the inspector specified.

The IA hates signing off work done by hangar faries.....none of them are A&P's.

[orionflt]

The IA hates signing off work done by hangar faries.....none of them are A&P's.

A very true statement, but they don't mind them opening and closing all the panels...

[Hector]

Here is the $7 sprayer from Lowes that I used. It works well on the flaps also. I've found that you need a second person to work the pedals back and fourth. Bleeding is messy and not really all that much fun, so if you have any leaks or need hoses or seals replaced do all of it at once.

I have this exact setup including a clear hose with a fitting that I screw to the reservoir. I also have a smaller hose that I attach to the overfill tube on top of the reservoir. During annual I pump a whole gallon of hyd fluid through the brakes while someone pumps the brakes. Seems to work quite well.

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[OR75]

Here is the $7 sprayer from Lowes that I used.  It works well on the flaps also.  I've found that you need a second person to work the pedals back and fourth. Bleeding is messy and not really all that much fun, so if you have any leaks or need hoses or seals replaced do all of it at once.

agreed. in theory, it can be a one person job. in reality, someone needs to be playing and taping on the pedals while the other person pushes fluid up the system.

[Guitarmaster]

What are you guys using for a fitting on the top of the reservoir? I am reasonable sure I have a big bubble in there somewhere and need to be able to pump through the caliper and be able to see the bubbles as they exit. Would it be possible to use a vacuum bleeder attached to the reservoir to pull the fluid rather than push?

[DonMuncy]

It shouldn't make any difference whether you push or pull, as long as the fluid flow is from the caliper up to the reservoir. But it is probably easier to make a pressure system than a vacuum.

[Guitarmaster]

Thanks Don. Sent from my iPad using Tapatalk