Brake Woes

[aerozuk]

Everything is ready to go on my Kitfox II accept the right brake does not work at all. I have a dual matco master cylinder set up with matco calipers and wheels. I have re-built everything in the system and swapped master cylinders to troubleshoot. Left brake still works, right still doesn't. When I depress the right pedal the puck comes out of the caliper and all, I replaced the pads. I need to check the pressure in the line with a gauge but I just wanted to know if anyone else has had a problem like this with the Matco Mfg. brake systems? BTW, I bought this aircraft used, it needed some work but has been flown 300 hours so the brakes worked at some point. Thanks.

Ryan

[lbushrod]

Make sure that your pedals are not even slightly depressed or disconnect them completely when filling reservoir on each side. If the check ball has any pressure on it, the Matco will not allow back flow.

I always disconnect my cylinders when filling (bottom-up) or bleeding my brakes. Good luck.

Pete

[wildlandjon]

Ryan: If you are running the plastic lines. Check that they don't move when you depress the pedal. These lines carry a small volume of fluid and if allowed to move around when pressure is applied your pressure will be going to moving the tubing rather than your brake pads. Also check for any kinks old or new this tubing doesn't like kinks, it's like putting a orfice in the line, and lastly check all of the connections, use a good quality brake cleaner and allow these connections to dry, then take some baby powder and put a lite coat on the fittings, cycle the break pedal (do this several times ) if any of the fittings change color you have a small leak and any leak even a small one will drop the pressure at the pads.

Good Luck
Jon

[Slyfox]

The plastic lines are suppose to have an insert at the end. If you didn't put one in and tighten the line, well, it closes down the opening.

[lbushrod]

Just got back from a cross country flight where I lost my left brake. I had enough aviation brake fluid so I disconnected the left brake plunger from the pedal and refilled the reservoir. Still a little spongy so I went a-lookin'. I couldn't see any fluid or leak at the fittings so I pulled the seat and checked the lines.

I had brake fluid under my mixer hardware indicating a leak somewhere. When I started moving the line it snapped like a piece of glass right at the point where the chafing material exited the fuselage to the wheel struts.

Next time at the field I will replace all my brake lines down to the wheels.

Concerns

1. I guess these lines can deteriorate and need to be replaced periodically. The brittleness concerns me especially close to a flex point.

2. I have always used aviation fluid and wonder if there is an alternative since I am no longer next door to Spruce.

3. If I had any cross-wind landings without my left brake I could be in a whirl of trouble, literally.

I just completed my annual inspection of the whole airplane and felt confident that everything was in good shape. I did not flex the brake lines to see if they were brittle. If I had I would have found the problem and had less mess to clean up.

Does anybody out there have an acceptable alternative to aviation grade brake fluid?

I'll watch the posts.

Pete

[DesertFox4]

Change out the plastic to stainless steel braided lines. No more problems.

[Mogas]

As I understand it, ordinary auto ATF (automatic transmission fluid) can be used in place of Aeroshell fluid 4.
We use ATF here in our hydraulic brake systems.
It is probably best you immerse an old O ring from your system in ATF for a few days to check for swelling and disintegration before charging the system with it.

[DanB]

Be careful just trying out different brake fluids. The fluid you use should have a high flash point if any at all. Fires have taken planes out when a leak develops at a wheel and the braking upon landing generates the heat.

[lbushrod]

My system used 1/8" nylaflow plastic tubing. I could not find 1/8" braided tubing in the spruce catalog. Maybe I can go to a larger sized fitting but understand that nylflow is pretty much a standard for experimental.

Also learned that the nylaflow does deteriorate over time. My plane is 14 years old so it is reasonable that the lines should go south eventually. I was advised to put a 90 degree bend in the tube to see if it breaks, easily done with new tubing.

Also heard that ATF is acceptable or synthetic auto brake fluid. I just wanted an alternative.

Thanks for the responses.

Pete

[Brett]

Pete,



I have been helping home builders for over 3 years, with brake and fuel lines.
I am sure that together we can make lines to fit your build.