Tips, Tricks, Info on Matco MC-5 master cylinder

[barnstorm2]

I have toebrakes that use the vertical Matco MC-5 master cylinders.

One has twice the travel as the other so I am assuming I need to add some fluid to the one with more travel.

Do I just remove the screw and guess how much brake fluid (and what kind of fluid) to add or do I remove the circlip and add fluid that way?

I have no manual so any advise would be most helpfull.


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[JEFF TIPTON]

Use 5606 hydraulic fluid. Add fluid from the caliper end. Fluid level should be about 3/4" from top of master cylinder.

Below is a link to Matco technical manual.

http://www.carttonic.com/files/file_download.php?fi_id=17859

[Rehan K.Janjua]

Hello Tim.

Fill with Automatic transmission fluid (ATF Dextron III)

If not sure drain all out and refill the system.

Fill the master cylinder by simply allowing the cylinder to suck fluid in by it self.
Push the cylinder shaft in, letting out air and sucking back fluid in.

Hope I'm making sense.

Best Wishes.
Rehan

[Caribean_gyro]

buy an oil can pump. put aplastic clear tubbing from the pump tip to the caliper bleeder. take the red plug from the matco out. pump from caliper up. this takes the air out. Now you will see some drip when you move the pedal forard. becasue you are full to the max. but this goes away is 2 or 3 tries.

chuckP

[barnstorm2]

Thanks guys!

Chuck, I used a syringe. It seemed to work out well. Thanks for hte idea. I did not have a red plug in mine.

Thanks for the manual Jeff. I think I read it right and with my setup I needed to add the fluid at the master cylinder. I hope I was right.

Thanks Rehan, It seems to be functioning just like the other one now with no leakage. It appeard to have regular brake fluid in it, but I might do a full drain sometime when I have more time.

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[JEFF TIPTON]

The important thing regardless how you did it, it works. If you get air in the line bleeding from below works best. Happy flying.

[Brent Drake]

Tim, Gary and I use a DOT 5 power steering fluid in ours. I have a leak and it is hard to stop. It uses about a teaspoon full every 10 hours of flight

[barnstorm2]

Tim, Gary and I use a DOT 5 power steering fluid in ours. I have a leak and it is hard to stop. It uses about a teaspoon full every 10 hours of flight

Thank you Brent,

Will Dot-5 mix with Dot-3 if that is what is already in mine?


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[scottessex]

NO Do not mix dot5 and dot 3. Dot 5 is synthetic based, and dot 3 is not. They will mix and form a nice jello-like mess. If you want to flush the system, remove it and clean all parts and rubber parts with denatured alcohol and then refill. Dot3 removes paint and attracts moisture. Dot 5 will not harm paint but it has a lower boiling point. I have done this on mine, as well as many motorcycles, the standard Harley fluid is dot5.
I would flush and clean it and then use ATF or DOT5.

[Arnie Madsen]

Much good advice above on fluids etc. However your problem will likely be related to "no pressure" in the brake system when not in use. If you were to step on the toe brakes with all your weight you probably could not get it to leak. However with no pressure and parked , the hydraulic seal is not being pressed "tight to the shaft" and seepage can occur either by air in or fluid out during daily warming and cooling while parked. Modern hydraulic systems are set up to keep "some pressure" in the systems to prevent this. On your Gyro I don't know what to recommend . My best guess is that "gravity alone" from the weight of the fluid in the master cylinders could supply enough light pressure to keep it sealed but most likely when the master cylinder is at rest , the orfice to the wheel slave cylinders is closed off (by the secondary piston in the master cylinder) so the wheel cylinders have no choice but to breath and seep thru their seals during daily warming and cooling cycles . (even when parked) The back of the master cylinder will leak a bit for the same reason (into the boot) , the seepage will then attract some moisture and rust will form. As I said , your best bet is to take some of the posted advice above and use a brake fluid that does not attract moisture or eat your painted surfaces. Completley bleeding the air from the brake system helps a lot also. Any Air in the system tends to expand and contract more than fluids during daily warming and cooling cycles.

Scott Essex post above makes sense on fluids.

I'm sure you wanted to know all that .... just when you are going flying we tell you to put the brakes on ... ha....!!

ps: my thinking is more in line with one of your other posts where you talked about brake fluid leaking. Is this the same machine. ?

Greetings from Canada
Arnie

[barnstorm2]

Thanks!!

I LOATH brake work. The master cylinders on my AirCommand SxS are a %@#534 pain in the @#%$$^$ to clean, fill and bleed.

I have some more spring cleaning to do and once that is done and I have my annual then the next big rain day I will flush the system and filler-up with a better fluid.

I am very happy that they are MUCH easyer to fill then the AirCommand MasterCylinders. Those I practically had to submerge to get to fill properly. Also, with one MasterCylinder per brake/caliper it should be easyer also. The AC has 1 MasterCylinder operating 2 calipers with a T-Connection.

These things SEEM like they wont take much time effort or make much of a mess when you plan them but murphy likes to get me on brake systems and the time always spins out of the planned boundrys.

Dammit man I'm a pilot not a A&P!

Of course even if we did not have to build and maintain our own craft I still would be too cheap to pay an A&P to bleed my brakes soo.... I guess I am a repairman like it or not!!

I have been thinking about how some light pressure might be applied but it seems like the best route is still to go with MasterCylinder Diapers (other thread) for now.

Thanks for all the advise guys! I have her topped-off now and I will drain and refill her after my annual and report back....


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[JEFF TIPTON]

Perchance the leak is caused by the wrong type of fluid. The o-rings that were delivered in the master cylinders are nitrile rubber and use 5606 hydraulic fluid. Reference the following link item 4.

http://www.carttonic.com/files/file_download.php?fi_id=17859