Master cylinders

I have some Gerdes master cylinders that were given to me years ago
which I am just now planning on using. Don't know much about them,
but was wondering if it wouldn't be prudent to have them be rebuilt
( overhauled ) before I use them, since they've been on the shelf for
so long. Is it actually possible to have them be overhauled and would
it be cost effective to do so? Thanks

Neal

On Fri, 11 Jul 2008 23:59:21 -0700 (PDT), wrote:

I have some Gerdes master cylinders that were given to me years ago
which I am just now planning on using. Don't know much about them,
but was wondering if it wouldn't be prudent to have them be rebuilt
( overhauled ) before I use them, since they've been on the shelf for
so long. Is it actually possible to have them be overhauled and would
it be cost effective to do so? Thanks

Neal

Neal you have a gem there in your hands.they are one of the neatest
little pieces of aviation kit ever invented.

the aircraft brake fluid in them, the red stuff, is not hydroscopic so
it never absorbs moisture. the innards of your master cylinders should
be in absolutely pristine condition. they may need a flush out to
remove accumulated crap but the worst you should find is worn o-rings.

in each side of your brake system there are 3 o-rings. 2 in the master
cylinder and 1 in the wheel puck.
the master cylinder has a feature known as a free piston. this piston
has one o-ring that makes the side seal. in the face of the pushrod is
another tiny o-ring that seals against the face of the free piston
when you apply toe brake to push the piston down.
these are the easiest things in the world to recondition if they are
old but in good nick.
buy the proper o-rings from your local aviation shop, my last ones
were under $aus20 for the 6 o-rings.

getting most of them apart involves taking the circlip out of the top.
this is a standard circlip and is about 3,000 times as stiff as it
needs to be. once you get that out without damaging anything the rest
is easy.
just slide it all apart. take the old o-rings out and put in the new
ones and your "reconditioning" is done. just remember to lube up the
new rings in brake fluid before putting them in position to prevent
nicking them.
reassemble, refill with red aviation brake fluid (actually an
automatic transmission fluid) and you will have pristine reconditioned
master cylinders.

you can find an exploded view of the innards of your cylinders in the
middle of an old cessna repair manual. in the 100 series cessna manual
it is figure 5-23 on page 5-37. it gives a perfect idea of how it all
goes together.

......actually I'm lying. they've been on the shelf for so long now
they'll be totally stuffed. mate I'll take them off your hands for $15
and I'll pay the express postage :-) :-) :-)

Stealth (you have a gem there) Pilot

Stealth Pilot wrote:

reassemble, refill with red aviation brake fluid (actually an
automatic transmission fluid) and you will have pristine reconditioned
master cylinders.

Excellent post, Stealth, except avoid the red aviation fluid. Well, some of the red aviation fluid. The stuff is
fairly flammable. Many designs use a hard aluminum line down to the brakes. Overform the hard line, and aluminum will
eventually break, and possibly spew flammable brake fluid onto a hot break. If that happens to you, you'll be damn
lucky if you have a quick thinking nephew handy with a gallon just of anti-freeze or some such silly thing.

The airforce got tired for brake fires and had a drop-in replacement formulated with a higher break point. If it is
good enough for the Stealth Fighter, it should be good enough for the Stealth Pilot 8*)

8351 is the magic number the stuff is called (I think). I ordered a gallon online for $20 or so. Enough for SEVERAL
airplanes. Big metal can. I use a sheet metal screw through a small o-ring to seal up all the extra.

In article ,
Ernest Christley wrote:

Stealth Pilot wrote:

reassemble, refill with red aviation brake fluid (actually an
automatic transmission fluid) and you will have pristine reconditioned
master cylinders.

Excellent post, Stealth, except avoid the red aviation fluid. Well, some of
the red aviation fluid. The stuff is
fairly flammable. Many designs use a hard aluminum line down to the brakes.
Overform the hard line, and aluminum will
eventually break, and possibly spew flammable brake fluid onto a hot break.
If that happens to you, you'll be damn
lucky if you have a quick thinking nephew handy with a gallon just of
anti-freeze or some such silly thing.

The airforce got tired for brake fires and had a drop-in replacement
formulated with a higher break point. If it is
good enough for the Stealth Fighter, it should be good enough for the Stealth
Pilot 8*)

8351 is the magic number the stuff is called (I think). I ordered a gallon
online for $20 or so. Enough for SEVERAL
airplanes. Big metal can. I use a sheet metal screw through a small o-ring
to seal up all the extra.

What about materials compatibility with standard O-rings? What about
toxicity and special handling requirements? Some fluids are quite toxic.

--
Remove _'s from email address to talk to me.

On Mon, 14 Jul 2008 20:36:22 -0400, Orval Fairbairn
wrote:

In article ,
Ernest Christley wrote:

Stealth Pilot wrote:

reassemble, refill with red aviation brake fluid (actually an
automatic transmission fluid) and you will have pristine reconditioned
master cylinders.

Excellent post, Stealth, except avoid the red aviation fluid. Well, some of
the red aviation fluid. The stuff is
fairly flammable. Many designs use a hard aluminum line down to the brakes.
Overform the hard line, and aluminum will
eventually break, and possibly spew flammable brake fluid onto a hot break.
If that happens to you, you'll be damn
lucky if you have a quick thinking nephew handy with a gallon just of
anti-freeze or some such silly thing.

The airforce got tired for brake fires and had a drop-in replacement
formulated with a higher break point. If it is
good enough for the Stealth Fighter, it should be good enough for the Stealth
Pilot 8*)

8351 is the magic number the stuff is called (I think). I ordered a gallon
online for $20 or so. Enough for SEVERAL
airplanes. Big metal can. I use a sheet metal screw through a small o-ring
to seal up all the extra.

What about materials compatibility with standard O-rings? What about
toxicity and special handling requirements? Some fluids are quite toxic.

I've never heard of a fire in a light aircraft's brakes so I'll
continue using armour braided flexible lines, standard aircraft grade
o-rings and red aviation brake fluid.
it works, it has had no problems in 20 years use, so I'll keep using
it.

the tin I've got will last me about 180 years. :-)

you realise of course dont you that there are brake fluids designed
for other types of aircraft that you wouldnt want within miles of a
light aircraft. some are quite toxic.
just because it was made for the stealth fighter doesnt mean it is
even remotely suitable for use in cleveland 5.00x5 systems.

btw he hasnt replied. do you think I offerred too much for the stuffed
units he has? :-) :-) :-)
Stealth Pilot

Stealth Pilot wrote:

I've never heard of a fire in a light aircraft's brakes so I'll

http://lancair.net/lists/flyrotary/Message/28204.html
Now you have 8*)
For the full story go to http://lancair.net/lists/flyrotary/List.html and enter "brake fire" in the search box.

http://www.vansairforce.com/communit...ead.php?t=4737
And so has Cirrus.

continue using armour braided flexible lines, standard aircraft grade
o-rings and red aviation brake fluid.

My gear retracts, so I pretty much had to use flex lines, but I've concluded that one-off, hand-formed hard lines all
the way out to the brakes is a serious problem waiting to happen. The hand-forming work hardens the aluminum, making it
prone to eventually cracking.

you realise of course dont you that there are brake fluids designed
for other types of aircraft that you wouldnt want within miles of a
light aircraft. some are quite toxic.
just because it was made for the stealth fighter doesnt mean it is
even remotely suitable for use in cleveland 5.00x5 systems.

It was designed as a drop in replacement. The correct number is MIL-H 83282. This thread contains a little more
information: http://www.vansairforce.com/communit...ead.php?t=4737 Includes information about o-ring compatibility.

If I had a gallon of 5606 sitting on the shelf, I probably wouldn't switch; but if I was looking to buy a gallon, I
would be remiss not to look at the 83282


btw he hasnt replied. do you think I offerred too much for the stuffed
units he has? :-) :-) :-)
Stealth Pilot



Your price was so high that he probably didn't think you were serious. 8*)

On Mon, 14 Jul 2008, Ernest Christley wrote:

Excellent post, Stealth, except avoid the red aviation fluid. Well, some of
the red aviation fluid. The stuff is fairly flammable.

What about using plain old DOT3 automotive brake fluid? It's cheap,
available everywhere, and non-flammable.

wrote:
On Mon, 14 Jul 2008, Ernest Christley wrote:

Excellent post, Stealth, except avoid the red aviation fluid. Well,
some of the red aviation fluid. The stuff is fairly flammable.

What about using plain old DOT3 automotive brake fluid? It's cheap,
available everywhere, and non-flammable.


http://www.xs11.com/tips/maintenance/maint1.shtml

Ernest Christley wrote:
wrote:
On Mon, 14 Jul 2008, Ernest Christley wrote:

Excellent post, Stealth, except avoid the red aviation fluid. Well,
some of the red aviation fluid. The stuff is fairly flammable.

What about using plain old DOT3 automotive brake fluid? It's cheap,
available everywhere, and non-flammable.


http://www.xs11.com/tips/maintenance/maint1.shtml

I don't believe it another XS11 rider here of all places...

Tony
aka Geezer

On Tue, 15 Jul 2008, Ernest Christley wrote:

wrote:
What about using plain old DOT3 automotive brake fluid? It's cheap,
available everywhere, and non-flammable.

http://www.xs11.com/tips/maintenance/maint1.shtml

Well I guess that's the definitive answer. From now on it's DOT3 for my
bird's brakes, not that dangerous flammable stuff the spamcan drivers are
stuck with. The only potential downside I can see is water absorption,
which is more than handled by an annual flushing with a couple bucks'
worth of brake fluid.