Plugging Brake Line

flyingriki · #1 05-17-2011, 08:46 PM

What do you folks use to plug an AN3 brake line when removing the brake from the axel to work on it? I hate to lose all the fluid in the line and have all that air to push out. Have tried golf tees, tape, etc. and all make a mess. Is it the same threads as an AN3 bolt or some brass plumbing plug from the hardware store or......?

Thanks!!

roee · #2 05-17-2011, 08:54 PM

To plug a flared tube/hose, use an AN806 flared tube plug.

http://www.aircraftspruce.com/catalo...s/an806-2d.php

gasman · #3 05-17-2011, 11:54 PM

Quote:

Originally Posted by flyingriki

What do you folks use to plug an AN3 brake line when removing the brake from the axel to work on it? I hate to lose all the fluid in the line and have all that air to push out. Have tried golf tees, tape, etc. and all make a mess. Is it the same threads as an AN3 bolt or some brass plumbing plug from the hardware store or......?

Thanks!!

There should be enough flex in your loop to slide off the cylinder to remove the pad without disconnecting the fluid line. In fact, the only time that you need to remove the brake fluid line is if you are replacing the line or the brake cylinder...... Here is where Bonaco lines would work great.

videobobk · #4 05-18-2011, 08:39 AM

I did this just last week as part of my condition inspection (needed to rebuild a brake cylinder.) While the plug is the best answer, I didn't have one. I took a left-over brake line pass-through (anything with #3 threads will do) and made a small plug for it. Anything to make it fluid-tight. I suppose you could use RTV and left it harden; I made a brass plug on my lathe.

If you are rebuilding a cylinder, here are some further hints: Make sure the reservoir is full before you loosen the fitting as you will lose some fluid. Plug it as quick as you can, and tighten the blug. Rebuild the cylinder (I clean up the bore and groove with fine emery cloth) and re-install it finger tight with the bleeder valve pointed up. Make sure the piston is fully in. Loosen the bleeder valve and wait for fluid to appear. Close the bleeder, rotate the cylinder back to the proper position, install it along with the pads, and tighten the bleeder and line. This way there should be no air in the cylinder or line, and you don't lose much fluid. Refill the reservoir. Done. No bleeding of the brake line necessary.

Bob Kelly

Bob Kelly

flyingriki · #5 05-18-2011, 10:56 AM

Thanks Bob and Roee. Found the plugs at Skyranch, which is close by.
Am redoing O-rings etc.
Why would Bonaco be 'better'....?

Greg Arehart · #6 05-18-2011, 09:08 PM

Bonaco (or a similar flexible line) is better than the rigid aluminum lines because 1) it's easier to move around when doing this sort of maintenance; and 2) it's not likely to work-harden and crack.

Another tip - put a solid plug in the top of the master cylinder and the vacuum will keep most or all of the fluid in the line.

greg

mxc5tc · #7 05-18-2011, 10:30 PM

Quote:

Originally Posted by Greg Arehart

Another tip - put a solid plug in the top of the master cylinder and the vacuum will keep most or all of the fluid in the line.

greg

If I'm in a hurry, I just rubber band plastic wrap across the top of the master cylinder (automotive & aircraft). Otherwise, I'll use a modified master cylinder cap with a vacuum fitting and pull about 10" of vacuum with a hand vacuum pump.

David-aviator · #8 05-19-2011, 05:36 AM

Quote:

Originally Posted by Greg Arehart

Bonaco (or a similar flexible line) is better than the rigid aluminum lines because 1) it's easier to move around when doing this sort of maintenance; and 2) it's not likely to work-harden and crack.

Another tip - put a solid plug in the top of the master cylinder and the vacuum will keep most or all of the fluid in the line.

greg

I have a cracked flare right now up where the line attaches to the fitting at the fuselage. Its been tightened a time or two and needs replacing - will have to look at the Bonaco. Thats with the left brake.

The right brake line broke at the brake fitting a couple years ago and was replaced with an fuel pressure line from Van's. That has worked so far but the line is not quite long enough to reach the fuselage fitting so there is a connection to aluminum line just below.