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Brake components and seals

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aerosiam

Joined: 26 May 2008
Posts: 59

Posted: Wed Nov 03, 2010 9:34 am Post subject: Brake components and seals

The brake system on our 4 year old plane was stripped down for inspection and to renew all the seals and O rings. 



This is a straightforward task. One caliper needed honing due to minor corrosion. The other was done last year.



I attach a cellphone photo of the components and another photo showing the seals and their respective positions.

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hgmckay

Joined: 23 May 2006
Posts: 397

Posted: Wed Nov 03, 2010 12:29 pm Post subject: Brake components and seals

Paul,



Thanks for the photos. I have also just finished stripping down the 

hydraulic brake calipers and discs on my Allegro 2000. After 4 years on a 

grass strip the brass plungers on the calipers were froze. Took everything 

apart, cleaned everything, re-polished the brass plunger ever so lightly, as 

well as the inside of the caliper itself. Put in new "O" rings and rubber 

plunger as well as new brake pads. I have not re-filled the hydraulic system 

yet.



I did notice in your photos that you also disassembled the little master 

cylinder. Why did you do that? Was there a problem with it? I do have a 

question that I need some help on. What is the best way to re-fill the brake 

system on an Allegro 2000 with hydraulic brake fluid? I see no way to fill 

the system from the top down (i.e. through the master cylinder in the plane) 

with out disassembling the master cylinder itself, and then re-assembling 

it. This seems to be difficult and cumbersome. How do you re-fill your brake 

system (top down, or bottom up) and then bleed the system after re-filling?



Hugh McKay

Allegro 2000

Rotax 912 UL



--

Brian Carpenter

Joined: 06 Mar 2008
Posts: 26
Location: TAYLOR, AZ

Posted: Wed Nov 03, 2010 3:25 pm Post subject: Brake components and seals

Hugh, 



We have filled from the bottom -up,,, both sides at the same time.   Small oil type cans with plastic line. I have had a problem with pressure when the system gets cold.. I have replaced the gasket on the plunger in the master several times.. I may have a small burr inside.. For some reason it has been holding pressure for the last 6 months, we will see what happens when it gets cold again..



Brian

N3081X

Taylor Az



--- On Wed, 11/3/10, Hugh McKay <hgmckay(at)bellsouth.net> wrote:

[quote]

From: Hugh McKay <hgmckay(at)bellsouth.net>

Subject: Re: Allegro-List: Brake components and seals

To: allegro-list(at)matronics.com

Date: Wednesday, November 3, 2010, 1:25 PM



-->  Allegro-List message posted by: "Hugh McKay" <[url=/mc/compose?to=hgmckay(at)bellsouth.net]hgmckay(at)bellsouth.net[/url]>



Paul,



Thanks for the photos. I have also just finished stripping down the hydraulic brake calipers and discs on my Allegro 2000. After 4 years on a grass strip the brass plungers on the calipers were froze. Took everything apart, cleaned everything, re-polished the brass plunger ever so lightly, as well as the inside of the caliper itself. Put in new "O" rings and rubber plunger as well as new brake pads. I have not re-filled the hydraulic system yet.



I did notice in your photos that you also disassembled the little master cylinder. Why did you do that? Was there a problem with it? I do have a question that I need some help on. What is the best way to re-fill the brake system on an Allegro 2000 with hydraulic brake fluid? I see no way to fill the system from the top down  (i.e. through the master cylinder in the plane) with out disassembling the master cylinder itself, and then re-assembling it. This seems to be difficult and cumbersome. How do you re-fill your brake system (top down, or bottom up) and then bleed the system after re-filling?



Hugh McKay

Allegro 2000

Rotax 912 UL



--

_________________
BRIAN N3081X

aerosiam

Joined: 26 May 2008
Posts: 59

Posted: Wed Nov 03, 2010 11:21 pm Post subject: Re: Brake components and seals

Hugh

I replaced all the seals possible. I think the plunger seal in the master cylinder is important as Brian suggests. 



I had to pump the brake 3 times before startup to ensure I have sufficient pressure which suggests the fluid is slipping past the plunger seal. Then it would hold the 100 hp engine at 4,000 rpm for the mag check.



I agree with Brian that bottom up simultaneously works better.



Paul

Roger Lee

Joined: 10 Jan 2006
Posts: 1464
Location: Tucson, Az.

Posted: Thu Nov 04, 2010 6:37 am Post subject: Re: Brake components and seals

Hi Guys,



You should absolutely fill your system from the bottom up to float out the air in the system. You can use that little oil can and I did many years ago, but found a much better mousetrap so to speak for about $10. The oil can works, but is slow and doesn't always get the job done well. Here is an Ace Hardware one gallon bug sprayer. Just unscrew the tip and replace it with some clear tubing. Pour in the brake fluid which should be the 5600 aircraft brake fluid and never auto DOT fluid. Then pump up the sprayer with pressure with the little knob on top. Slightly squeeze the trigger and bleed any air out of the sprayer tubing. Attach it to the bottom break bleed valve on the bottom of the caliper, open the bleeder valve some and press the trigger. The system flushes so easily and fast that it sweeps all the air with it. I take a little water bottle with a piece of tubing taped in it and place it up at the reservoir and as the fluid flushes up and out with the air the bottle catches the overflow. I do both sides then get in and pump the brake handle or toe brakes about 10-15 times fast and fairly hard to move any trapped bubbles around. Then a quick second flush. Works perfect every time and never a any air left in the system. The fluid waste is only about 2-3 oz. The auto DOT fluid will eat your "O" rings and cause leaks in the tubing of your brake system. If you are having any issues with the brakes and seals and use the DOT fluids now you know why. This is one of my best tools in my shop for $10 and it takes no time and no hassle to bleed a brake system.

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_________________
Roger Lee
Tucson, Az.
Rotax Instructor & Rotax IRC
Light Sport Repairman
Home 520-574-1080 TRY HOME FIRST
Cell 520-349-7056

Roger Lee

Joined: 10 Jan 2006
Posts: 1464
Location: Tucson, Az.

Posted: Thu Nov 04, 2010 6:40 am Post subject: Re: Brake components and seals

P.S.



If you want to keep corrosion of your planes metal parts Boeing T-9 works very well. It was made for the Boeing aircraft company and will seal out all moisture. Do no spray it on thing like brake disc or pads. It works and can be used on an engine or any metal part or metal type (aluminum or steel)

_________________
Roger Lee
Tucson, Az.
Rotax Instructor & Rotax IRC
Light Sport Repairman
Home 520-574-1080 TRY HOME FIRST
Cell 520-349-7056

Brian Carpenter

Joined: 06 Mar 2008
Posts: 26
Location: TAYLOR, AZ

Posted: Thu Nov 04, 2010 8:50 am Post subject: Brake components and seals

Roger,

The Allegro calls for Dot 3,4 Brake fluid!!!! 



brian



Sent from Brian's iPod



On Nov 4, 2010, at 7:40, "Roger Lee" <ssadiver1(at)yahoo.com> wrote:






P.S.



If you want to keep corrosion of your planes metal parts Boeing T-9 works very well. It was made for the Boeing aircraft company and will seal out all moisture. Do no spray it on thing like brake disc or pads. It works and can be used on an engine or any metal part or metal type (aluminum or steel)



--------

Roger Lee

Tucson, Az.

Light Sport Repairman - Maintenance Rated

Rotax Repair Center

Home 520-574-1080  TRY HOME FIRST

Cell 520349-7056





Read this topic online here:



http://forums.matronics.com/viewtopic.php?p=318122#318122

_________________
BRIAN N3081X

Roger Lee

Joined: 10 Jan 2006
Posts: 1464
Location: Tucson, Az.

Posted: Thu Nov 04, 2010 3:52 pm Post subject: Re: Brake components and seals

Hi Brian,



DOT fluid might be suggested, but if all the components in the system don't then you will have all these type issues you guys are talking about. I have seen DOT brake fluid eat many "O"rings and seals. I was a victim many years ago because someone said it was ok. Just something to consider.

_________________
Roger Lee
Tucson, Az.
Rotax Instructor & Rotax IRC
Light Sport Repairman
Home 520-574-1080 TRY HOME FIRST
Cell 520-349-7056

brad(at)vision-technology
Guest

Posted: Thu Nov 04, 2010 4:26 pm Post subject: Brake components and seals

Hi Roger,



Just so I'm clear on this, do you suggest we ignore the Allegro maintenance

manual that specifically calls for DOT 3/4?



Thanks for your insight and experience!



..Brad...



N221FA / Bismarck ND



--

Roger Lee

Joined: 10 Jan 2006
Posts: 1464
Location: Tucson, Az.

Posted: Thu Nov 04, 2010 5:13 pm Post subject: Re: Brake components and seals

What I'm saying is you ought to be very suspicious of DOT fluids in your brake system and if people continue to have issues then I would change and file for an LOA for the 5600. I have filed many LOA's not only for individuals, but fleet approvals for the Flight Design CT. I have changed the entire brake system from the Marc Ingegno brakes to Matco's just for an example. The factory is not always right and can and does use help from people in the field. Yes you should get an LOA for the 5600 fluid change. So long as you have a good reason and can back up any LOA change Mfg's will usually try to accommodate people.

Brian from the post above can tell you I do this stuff for a living and help people with different SLSA's and ELSA's. Keep an eye on things and don't be afraid to make a change.

_________________
Roger Lee
Tucson, Az.
Rotax Instructor & Rotax IRC
Light Sport Repairman
Home 520-574-1080 TRY HOME FIRST
Cell 520-349-7056

aerosiam

Joined: 26 May 2008
Posts: 59

Posted: Thu Nov 04, 2010 8:58 pm Post subject: Re: Brake components and seals

What about DOT 5 silicon brake fluid (not 5.1) ?



Paul

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