REFLECTOR: air in brake line

Mon Apr 18 12:09:33 CDT 2011

Barry, 

You basically fill the calipers with fluid "on the bench" (and over a catch tub). You can fill it slowly from the top with the calipers in their widest position. Then you rotate them some and let the bubbles work their way out of the insides and up to the top. I ended up filling them from the bottom using an oil can filled with brake fluid and a fitting I found in my shop. 

Note:  On my brakes, the bleeder nipple is on the top and the fluid line is on the bottom).

Once you think you have all the bubbles out of the calipers, then you plug them with a plastic cap and reinstall on the airplane. 

Then I filled the brake lines in the airplane .. and basically bled the line. Then I hooked the 2 together. My thought was to have as little air trapped in the system as possible when you start to bleed the whole system. This worked pretty darn good, as I only had a few bubbles to get rid of. 

Kurt 

-----Original Message-----
From: Barry Gibbons <gibbons at as.net>
To: 'Velocity Aircraft Owners and Builders list' <reflector at tvbf.org>
Sent: Mon, Apr 18, 2011 10:32 am
Subject: Re: REFLECTOR: air in break line

How did you bench bleed the Caliper?
Barry

-----Original Message-----
From: reflector-bounces at tvbf.org [mailto:reflector-bounces at tvbf.org] On Behalf Of nmflyer1 at aol.com
Sent: Monday, April 18, 2011 8:38 AM
To: Jim_Agnew_2 at yahoo.com; reflector at tvbf.org
Subject: Re: REFLECTOR: air in break line

Right again Jim, 

I "bench Bled" my calipers Before I installed them. 

I also gravity filled the lines before I hooked up the calipers.

Then I hooked up the brake line to the calipers and bled from the bottom up (with the for-mentioned oil can trick). 

Now, I have a different style of master cylinders, but I accomplished the whole thing in about an hour. Seems fine now.

Kurt 

-----Original Message-----
From: Jim Agnew <jim_agnew_2 at yahoo.com>
To: Velocity Aircraft Owners and Builders list <reflector at tvbf.org>
Sent: Mon, Apr 18, 2011 9:12 am
Subject: Re: REFLECTOR: air in break line

Before you go nuts trying to bleed the brakes take a look at the attached diagram for Matco brakes.  You will notice that the connections between the pistons are not in a straight line and require you to fill from the bottom piston up while adjusting the caliper position to allow the air trapped in the piston to escape up.  Note the pistons are hollow so the process of keeping the connections vertical also requires rocking the caliper side to side at the same time.

Jim

James F. Agnew

Jim_Agnew_2 at Yahoo.Com

Tampa, FL

Velocity 173 Elite Aircraft Completed & Flying

From: Jerry Brainard <Jerry at jlbent.com>
To: Velocity Aircraft Owners and Builders list <reflector at tvbf.org>
Sent: Mon, April 18, 2011 9:49:44 AM
Subject: Re: REFLECTOR: air in break line

Just to be complete, did you use the little tubing inserts for the brake line fittings?  They go into the line to strengthen the tube under the clamping force of the brass ferrule.

Do you have a parking brake?  We were never able to successfully bleed the brakes with that installed.  I assume it was the installation position because others have been successful.

Another consideration might be to elevate the nose to help the air to move to the cylinders.

Bleeding the brakes can be one of the most maddening things you will do on the Velocity.

Jerry Brainard

Jerry at JLBEnt.com

From: reflector-bounces at tvbf.org [mailto:reflector-bounces at tvbf.org] On Behalf Of Barry Gibbons
Sent: Sunday, April 17, 2011 9:48 PM
To: 'Velocity Aircraft Owners and Builders list'
Subject: REFLECTOR: air in break line

Hello

For about two month I have been trying to bleed my left break. I replace the master cly. Three times, rebuild the caliber twice; replace break line to gear leg and still getting air in the line. No sign of fluid leak. It looks like it coming from the master cyl. After I reverse flow and no bubbles I stop. Then when I push on the brake you can see a bubble come from Master cyl. You wait until the next day you can see more air in the line. But changing it three times it has to be something else. Any suggestion on what I can try or where the air might be coming in from. I have done reverse flow and pumping break and bleeding at caliper.

Barry

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