bleeding Duo Discus brakes

[Morgan[_2_]]

Looking for advice on bleeding the brakes on my Duo with the tost 30-9
caliper. I replaced a shot bleeder valve with a new stahlbus valve,
but after futzing with the system for over an hour, I can't get the
brake to firm up to an acceptable level.

I've tried using a suction device to pull fluid (Dot 4 in the Duo)
down through the line. I've also gone with my normal old standby of
pushing fluid up through the brake using a syringe. The Stahlbus
valve is not working as advertised or rather the brake isn't. The
brake doesn't seem to be creating enough pressure to overcome the
spring tension on the check valve.

The best I've been able to get to so far is a fairly spongy grip on
the rotor. Enough that turning by hand isn't possible, but it doesn't
feel like it would slow you down much when you needed it.

Basically it just doesn't feel like the master cylinder is drawing
fluid in or maybe there is a hidden air bubble.

Any thoughts from the internet hive on the quirks of this beast?
It's certainly been a much greater hassle than I expected. I'm
guessing at this point that either there is a trick that I don't know
about or something is malfunctioning.

Thanks,

Morgan

[bumper[_4_]]

Not on the Duo specifically, but some thoughts none-the-less.

Best to use a pressure pot (can be a good quality pump oil can, but
better is a small pump-up garden sprayer modified for the job, as this
allows some serious through-put to overcome and move out bubbles in
high spots).
Cycle the brake lever a few times while pumping the fluid up.

Note that some installations don't have the brake line going into the
caliper at the top, thus there can be a stubborn bubble in the caliper
itself. In this case, remove caliper and but a clamp on piston to keep
it from coming out. Then bleed with brake line at top.

To get more through put, you will need remove all brake fluid from the
reservoir with a syringe. Better is to intall a fitting in the
existing cap vent hole so you can install a temporary tube to take off
the excess brake fluid. Depending on existing cap vent hole, you may
be able to use a large hypodermic needle for this (McMaster-Car sells
them 1/8" OD) or you can drill hole bigger and install a nipple to
accept the vent tube. Pump brake fluid up until no more bubbles exit
vent tube - - which can be placed in a container so bubbles are
clearly visible.

Interesting that the Duo uses automotive Dot fluid?? I know the Stemme
does also. Schleicher uses the more common (at least in the USA for
small GA) Mil Spec 5606 fluid (the good ole red stuff). You cannot mix
or substitute the two as 5606 calls for Buna-N seals and O-rings,
while Dot fluid takes EPDM rubber seals.

Tost buys some US Cleavland brake parts, such as the 30- series
caliper, and replaces the Buna-N O-rings with EPDM. The Cleveland
calipers, and their early non-anodized pistons, tend to corrode due to
moisture as the Dot fluids are hygroscopic. Later pistons, after the
mid-90's or so, are anodized, but the caliper bore is still prone to
corrode when Dot fluids are used, and this leads to leaks and poor
braking. So be sure to check caliper bore condition if using Dot
fluids. The long term fix is to sleave the bores with brass liners and
anodize the pistons if they're the early ones.

bumper
MKIV & QV
Minden

[Mike the Strike]

On Jan 11, 12:54*am, bumper > wrote:
> Not on the Duo specifically, but some thoughts none-the-less.
>
> Best to use a pressure pot (can be a good quality pump oil can, but
> better is a small pump-up garden sprayer modified for the job, as this
> allows some serious through-put to overcome and move out bubbles in
> high spots).
> Cycle the brake lever a few times while pumping the fluid up.
>
> Note that some installations don't have the brake line going into the
> caliper at the top, thus there can be a stubborn bubble in the caliper
> itself. In this case, remove caliper and but a clamp on piston to keep
> it from coming out. Then bleed with brake line at top.
>
> To get more through put, you will need remove all brake fluid from the
> reservoir with a syringe. Better is to intall a fitting in the
> existing cap vent hole so you can install a temporary tube to take off
> the excess brake fluid. Depending on existing cap vent hole, you may
> be able to use a large hypodermic needle for this (McMaster-Car sells
> them 1/8" OD) or you can drill hole bigger and install a nipple to
> accept the vent tube. Pump brake fluid up until no more bubbles exit
> vent tube - - which can be placed in a container so bubbles are
> clearly visible.
>
> Interesting that the Duo uses automotive Dot fluid?? I know the Stemme
> does also. Schleicher uses the more common (at least in the USA for
> small GA) Mil Spec 5606 fluid (the good ole red stuff). You cannot mix
> or substitute the two as 5606 calls for Buna-N seals and O-rings,
> while Dot fluid takes EPDM rubber seals.
>
> Tost buys some US Cleavland brake parts, such as the 30- series
> caliper, and replaces the Buna-N O-rings with EPDM. The Cleveland
> calipers, and their early non-anodized pistons, tend to corrode due to
> moisture as the Dot fluids are hygroscopic. Later pistons, after the
> mid-90's or so, are anodized, but the caliper bore is still prone to
> corrode when Dot fluids are used, and this leads to leaks and poor
> braking. So be sure to check caliper bore condition if using Dot
> fluids. The long term fix is to sleave the bores with brass liners and
> anodize the pistons if they're the early ones.
>
> bumper
> MKIV & QV
> Minden

After replacing the seals on my Discus 2 hydraulic brake, the only way
we could bleed the system was to pump upwards from the bottom to
remove some stubborn air bubbles. It was a pig to do and took a long
time to get it properly working.

I have no idea why your syringe would not work, but all of Bumper's
suggestions sound good.

Mike

[Morgan[_2_]]

Bumper and Mike thanks for the suggestions. Adding the automatic vent
to the top of the cap sounds like a good move. I have pumped the
reservoir full from the bottom and wasn't seeing bubbles, but maybe
there is a big one hiding and being able to push more volume sounds
like a reasonable start. I have a big syringe from the pet store
that probably holds 3x the capacity of the system, but the reservoir
at the top becomes the limiting factor. The garden sprayer is another
great tip.

The caliper is mounted near vertical. I may pull it just to orient it
better and eliminate that variable.

Thanks again for the suggestions.

Morgan

[bumper[_4_]]

Good luck . . .

And if it is Dot fluid, be really careful about clean up, given some
time this stuff is as good a paint remover as anything else. Once upon
a long time ago, I thought I was being fastidious cleaning up and used
compressed air to blow out one of the tubes I'd used for bleeding. The
little bits of brake fluid spray settled unnoticed on my car hood and
fender some 25 feet away. Next morning that car had a serious case of
the measels.

bumper

[Dave Nadler]

IIRC, note not all Duos have the same setup as SH have
tried to improve it a few times now...

On Wednesday, January 11, 2012 11:10:10 AM UTC-5, Morgan wrote:
> The caliper is mounted near vertical. I may pull it just to orient it
> better and eliminate that variable.

Right, its still got a cavity trapping air in the mounted position.

Be careful with the adjustments.
Things I have seen, which you REALLY want to avoid:

(1) adjustment so that vent in top of master is blocked;
this is supposed to be a normally open system.

(2) adjustment so that the spoiler travel is restricted;
check that the spoilers can come full out (cases some
complaints about Duo spoilers !)

Hoe that helps,
Best Regards, Dave "YO electric"

[Craig[_2_]]

On Jan 11, 9:40*am, Dave Nadler > wrote:
> IIRC, note not all Duos have the same setup as SH have
> tried to improve it a few times now...
>
> On Wednesday, January 11, 2012 11:10:10 AM UTC-5, Morgan wrote:
> > The caliper is mounted near vertical. I may pull it just to orient it
> > better and eliminate that variable.
>
> Right, its still got a cavity trapping air in the mounted position.
>
> Be careful with the adjustments.
> Things I have seen, which you REALLY want to avoid:
>
> (1) adjustment so that vent in top of master is blocked;
> this is supposed to be a normally open system.
>
> (2) adjustment so that the spoiler travel is restricted;
> check that the spoilers can come full out (cases some
> complaints about Duo spoilers !)
>
> Hoe that helps,
> Best Regards, Dave "YO electric"

I have a Nimbus which I assume isn't too different regarding the
brakes. I rebuilt the entire brake system last winter and found that
using the oversize veterinary syringe and pushing fluid from the
bottom works well as long as the caliper is off the gear and oriented
so that the brake line port points straight up. Schemp does use DOT
fluid. I didn't find any severe pitting of the caliper or pistons,
but it's worth looking out for.

Best regards,
Craig

[Morgan[_2_]]

I'll pull the caliper before my next bleed attempt. I also picked up
a pump bottle and some hardware to potentially make this easier to do
solo.

My issue is probably made worse by the angle of the glider in the
driveway which causes it to sit very high in the cradle making the
angle to the caliper even farther off 90. I suspected that might be
contributing to the issue, and the comments would confirm that it
probably isn't helping.

I appreciate all of the feedback and support.

Morgan

[rhwoody]

On Jan 11, 12:30*am, Morgan > wrote:
> Looking for advice on bleeding the brakes on my Duo with the tost 30-9
> caliper. *I replaced a shot bleeder valve with a new stahlbus valve,
> but after futzing with the system for over an hour, I can't get the
> brake to firm up to an acceptable level.
>
> I've tried using a suction device to pull fluid (Dot 4 in the Duo)
> down through the line. *I've also gone with my normal old standby of
> pushing fluid up through the brake using a syringe. *The Stahlbus
> valve is not working as advertised or rather the brake isn't. *The
> brake doesn't seem to be creating enough pressure to overcome the
> spring tension on the check valve.
>
> The best I've been able to get to so far is a fairly spongy grip on
> the rotor. Enough that turning by hand isn't possible, but it doesn't
> feel like it would slow you down much when you needed it.
>
> Basically it just doesn't feel like the master cylinder is drawing
> fluid in or maybe there is a hidden air bubble.
>
> Any thoughts from the internet hive on the quirks of this beast?
> It's certainly been a much greater hassle than I expected. *I'm
> guessing at this point that either there is a trick that I don't know
> about or something is malfunctioning.
>
> Thanks,
>
> Morgan

Hi All, I have owned a lot of SH gliders and have had success doing
the following -
unbolt the brake cylinder and raise it up so there is no "loop" in the
brake line -
so the path from the brake calipers to the brake cylinder goes only
uphill -
first try to actuate the brake cylinder lever - sometimes this will
"burp" the air
bubble up into the brake cylinder - otherwise fill fluid from the
bottom nipple
until the air bubble goes into the brake cylinder reservoir - most
times the
air bubble will burp into the reservoir and no filling is necessary -
good luck,
Ralph Woodward

[Morgan[_2_]]

This pretty much nails what ended up working for me. I ended up
removing the whole system from the ship and flushing it forwards and
backwards to make sure there wasn't any old fluid or particles in the
system. Popped the piston out and inspected it and the cylinder wall
for corrosion and pitting. Overall things looked pretty good, but it
got a good cleaning while I was in there.

Funny, you'll jump through all sorts of hoops and delays to avoid
doing it the "hard way" and in the end that was the least traumatic
and fastest way to get it to work. It took me way longer than it
should have, but the upside is that I know my braking system inside an
out now and it is time for new pads as well.

Thanks for the tips.

Morgan




On Jan 16, 9:23*am, rhwoody > wrote:
> On Jan 11, 12:30*am, Morgan > wrote:
>
>
>
>
>
>
>
>
>
> > Looking for advice on bleeding the brakes on my Duo with the tost 30-9
> > caliper. *I replaced a shot bleeder valve with a new stahlbus valve,
> > but after futzing with the system for over an hour, I can't get the
> > brake to firm up to an acceptable level.
>
> > I've tried using a suction device to pull fluid (Dot 4 in the Duo)
> > down through the line. *I've also gone with my normal old standby of
> > pushing fluid up through the brake using a syringe. *The Stahlbus
> > valve is not working as advertised or rather the brake isn't. *The
> > brake doesn't seem to be creating enough pressure to overcome the
> > spring tension on the check valve.
>
> > The best I've been able to get to so far is a fairly spongy grip on
> > the rotor. Enough that turning by hand isn't possible, but it doesn't
> > feel like it would slow you down much when you needed it.
>
> > Basically it just doesn't feel like the master cylinder is drawing
> > fluid in or maybe there is a hidden air bubble.
>
> > Any thoughts from the internet hive on the quirks of this beast?
> > It's certainly been a much greater hassle than I expected. *I'm
> > guessing at this point that either there is a trick that I don't know
> > about or something is malfunctioning.
>
> > Thanks,
>
> > Morgan
>
> Hi All, *I have owned a lot of SH gliders and have had success doing
> the following -
> unbolt the brake cylinder and raise it up so there is no "loop" in the
> brake line -
> so the path from the brake calipers to the brake cylinder goes only
> uphill -
> first try to actuate the brake cylinder lever - sometimes this will
> "burp" the air
> bubble up into the brake cylinder - otherwise fill fluid from the
> bottom nipple
> until the air bubble goes into the brake cylinder reservoir - *most
> times the
> air bubble will burp into the reservoir and no filling is necessary -
> good luck,
> Ralph Woodward

[JJ Sinclair[_2_]]

On Jan 16, 1:56*pm, Morgan > wrote:
> This pretty much nails what ended up working for me. *I ended up
> removing the whole system from the ship and flushing it forwards and
> backwards to make sure there wasn't any old fluid or particles in the
> system. *Popped the piston out and inspected it and the cylinder wall
> for corrosion and pitting. *Overall things looked pretty good, but it
> got a good cleaning while I was in there.
>
> Funny, you'll jump through all sorts of hoops and delays to avoid
> doing it the "hard way" and in the end that was the least traumatic
> and fastest way to get it to work. *It took me way longer than it
> should have, but the upside is that I know my braking system inside an
> out now and it is time for new pads as well.
>
> Thanks for the tips.
>
> Morgan
>
> On Jan 16, 9:23*am, rhwoody > wrote:
>
>
>
> > On Jan 11, 12:30*am, Morgan > wrote:
>
> > > Looking for advice on bleeding the brakes on my Duo with the tost 30-9
> > > caliper. *I replaced a shot bleeder valve with a new stahlbus valve,
> > > but after futzing with the system for over an hour, I can't get the
> > > brake to firm up to an acceptable level.
>
> > > I've tried using a suction device to pull fluid (Dot 4 in the Duo)
> > > down through the line. *I've also gone with my normal old standby of
> > > pushing fluid up through the brake using a syringe. *The Stahlbus
> > > valve is not working as advertised or rather the brake isn't. *The
> > > brake doesn't seem to be creating enough pressure to overcome the
> > > spring tension on the check valve.
>
> > > The best I've been able to get to so far is a fairly spongy grip on
> > > the rotor. Enough that turning by hand isn't possible, but it doesn't
> > > feel like it would slow you down much when you needed it.
>
> > > Basically it just doesn't feel like the master cylinder is drawing
> > > fluid in or maybe there is a hidden air bubble.
>
> > > Any thoughts from the internet hive on the quirks of this beast?
> > > It's certainly been a much greater hassle than I expected. *I'm
> > > guessing at this point that either there is a trick that I don't know
> > > about or something is malfunctioning.
>
> > > Thanks,
>
> > > Morgan
>
> > Hi All, *I have owned a lot of SH gliders and have had success doing
> > the following -
> > unbolt the brake cylinder and raise it up so there is no "loop" in the
> > brake line -
> > so the path from the brake calipers to the brake cylinder goes only
> > uphill -
> > first try to actuate the brake cylinder lever - sometimes this will
> > "burp" the air
> > bubble up into the brake cylinder - otherwise fill fluid from the
> > bottom nipple
> > until the air bubble goes into the brake cylinder reservoir - *most
> > times the
> > air bubble will burp into the reservoir and no filling is necessary -
> > good luck,
> > Ralph Woodward- Hide quoted text -
>
> - Show quoted text -

Changing the fluid every 6 or 8 years is a very good idea. I checked
my system last year by having a helper (wife) pump the master cylinder
a few strokes and then hold the pressure as I bled out the pressure at
the brake.............just like we did in the 1934 Ford. You wouldn't
believe what came out, thick gooey stuff that wasn't even red anymore!
I had to repeat this for several cycles before the bled fluid started
showing red fluid. I also replace my pads when they show less than
1/8" which can be easuly seen with a flashlight and mirror.
Cheers,
JJ

[Karl Striedieck[_2_]]

On Jan 16, 6:05*pm, JJ Sinclair > wrote:
> On Jan 16, 1:56*pm, Morgan > wrote:
>
>
>
>
>
> > This pretty much nails what ended up working for me. *I ended up
> > removing the whole system from the ship and flushing it forwards and
> > backwards to make sure there wasn't any old fluid or particles in the
> > system. *Popped the piston out and inspected it and the cylinder wall
> > for corrosion and pitting. *Overall things looked pretty good, but it
> > got a good cleaning while I was in there.
>
> > Funny, you'll jump through all sorts of hoops and delays to avoid
> > doing it the "hard way" and in the end that was the least traumatic
> > and fastest way to get it to work. *It took me way longer than it
> > should have, but the upside is that I know my braking system inside an
> > out now and it is time for new pads as well.
>
> > Thanks for the tips.
>
> > Morgan
>
> > On Jan 16, 9:23*am, rhwoody > wrote:
>
> > > On Jan 11, 12:30*am, Morgan > wrote:
>
> > > > Looking for advice on bleeding the brakes on my Duo with the tost 30-9
> > > > caliper. *I replaced a shot bleeder valve with a new stahlbus valve,
> > > > but after futzing with the system for over an hour, I can't get the
> > > > brake to firm up to an acceptable level.
>
> > > > I've tried using a suction device to pull fluid (Dot 4 in the Duo)
> > > > down through the line. *I've also gone with my normal old standby of
> > > > pushing fluid up through the brake using a syringe. *The Stahlbus
> > > > valve is not working as advertised or rather the brake isn't. *The
> > > > brake doesn't seem to be creating enough pressure to overcome the
> > > > spring tension on the check valve.
>
> > > > The best I've been able to get to so far is a fairly spongy grip on
> > > > the rotor. Enough that turning by hand isn't possible, but it doesn't
> > > > feel like it would slow you down much when you needed it.
>
> > > > Basically it just doesn't feel like the master cylinder is drawing
> > > > fluid in or maybe there is a hidden air bubble.
>
> > > > Any thoughts from the internet hive on the quirks of this beast?
> > > > It's certainly been a much greater hassle than I expected. *I'm
> > > > guessing at this point that either there is a trick that I don't know
> > > > about or something is malfunctioning.
>
> > > > Thanks,
>
> > > > Morgan
>
> > > Hi All, *I have owned a lot of SH gliders and have had success doing
> > > the following -
> > > unbolt the brake cylinder and raise it up so there is no "loop" in the
> > > brake line -
> > > so the path from the brake calipers to the brake cylinder goes only
> > > uphill -
> > > first try to actuate the brake cylinder lever - sometimes this will
> > > "burp" the air
> > > bubble up into the brake cylinder - otherwise fill fluid from the
> > > bottom nipple
> > > until the air bubble goes into the brake cylinder reservoir - *most
> > > times the
> > > air bubble will burp into the reservoir and no filling is necessary -
> > > good luck,
> > > Ralph Woodward- Hide quoted text -
>
> > - Show quoted text -
>
> Changing the fluid every 6 or 8 years is a very good idea. I checked
> my system last year by having a helper (wife) pump the master cylinder
> a few strokes and then hold the pressure as I bled out the pressure at
> the brake.............just like we did in the 1934 Ford. You wouldn't
> believe what came out, thick gooey stuff that wasn't even red anymore!
> I had to repeat this for several cycles before the bled fluid started
> showing red fluid. I also replace my pads when they show less than
> 1/8" which can be easuly seen with a flashlight and mirror.
> Cheers,
> JJ

I've been unable to get the Duo wheel brake to work as it should. This
includes removing the entire system (caliper, lines, master cylinder)
and operating it on the bench with a piece of metal to simulate the
disc. In this configuration it works great - rock hard "brake pedal."
But it has to be disassembled to go back in the glider, and there it
is spongy again, no matter how much or how you bleed it. I thought the
problem might be partial retraction of the pucks due to temperature
changes, "potato chipped" disc, or vibration, so installed small
springs behind the pucks to keep them lightly against the disc. No
improvement.

It helps to pump up the brake with the stick mounted brake lever if
you have one, while in the landing pattern. Or cycle the air brakes
fully if you don't have the stick grip.

Another wheel brake problem with the Duo is a fundamental mechanical
issue. The force required to cycle the speed brakes all the way open
to the wheel brake actuation point gets higher as you slow down. While
flying at pattern speed the spoilers stay open by air pressure, but as
you slow down on the ground they get heavier as air speed no longer
helps keep the handle back. With little or no airspeed the amount of
force required to pull the handle all the way back is considerable,
with little left over to apply brake.

One solution I've employed for the latter is a long bungee cord that
pulls back on the spoiler handle. But this has a couple significant
safety issues that must be addressed. It must not be hooked up until
landing, and the pilot must then keep his/her hand on the spoiler
handle. A better procedure is to have the back seater help with the
pull.

[JJ Sinclair[_2_]]

On Jan 16, 7:39*pm, Karl Striedieck >
wrote:
> On Jan 16, 6:05*pm, JJ Sinclair > wrote:
>
>
>
>
>
> > On Jan 16, 1:56*pm, Morgan > wrote:
>
> > > This pretty much nails what ended up working for me. *I ended up
> > > removing the whole system from the ship and flushing it forwards and
> > > backwards to make sure there wasn't any old fluid or particles in the
> > > system. *Popped the piston out and inspected it and the cylinder wall
> > > for corrosion and pitting. *Overall things looked pretty good, but it
> > > got a good cleaning while I was in there.
>
> > > Funny, you'll jump through all sorts of hoops and delays to avoid
> > > doing it the "hard way" and in the end that was the least traumatic
> > > and fastest way to get it to work. *It took me way longer than it
> > > should have, but the upside is that I know my braking system inside an
> > > out now and it is time for new pads as well.
>
> > > Thanks for the tips.
>
> > > Morgan
>
> > > On Jan 16, 9:23*am, rhwoody > wrote:
>
> > > > On Jan 11, 12:30*am, Morgan > wrote:
>
> > > > > Looking for advice on bleeding the brakes on my Duo with the tost 30-9
> > > > > caliper. *I replaced a shot bleeder valve with a new stahlbus valve,
> > > > > but after futzing with the system for over an hour, I can't get the
> > > > > brake to firm up to an acceptable level.
>
> > > > > I've tried using a suction device to pull fluid (Dot 4 in the Duo)
> > > > > down through the line. *I've also gone with my normal old standby of
> > > > > pushing fluid up through the brake using a syringe. *The Stahlbus
> > > > > valve is not working as advertised or rather the brake isn't. *The
> > > > > brake doesn't seem to be creating enough pressure to overcome the
> > > > > spring tension on the check valve.
>
> > > > > The best I've been able to get to so far is a fairly spongy grip on
> > > > > the rotor. Enough that turning by hand isn't possible, but it doesn't
> > > > > feel like it would slow you down much when you needed it.
>
> > > > > Basically it just doesn't feel like the master cylinder is drawing
> > > > > fluid in or maybe there is a hidden air bubble.
>
> > > > > Any thoughts from the internet hive on the quirks of this beast?
> > > > > It's certainly been a much greater hassle than I expected. *I'm
> > > > > guessing at this point that either there is a trick that I don't know
> > > > > about or something is malfunctioning.
>
> > > > > Thanks,
>
> > > > > Morgan
>
> > > > Hi All, *I have owned a lot of SH gliders and have had success doing
> > > > the following -
> > > > unbolt the brake cylinder and raise it up so there is no "loop" in the
> > > > brake line -
> > > > so the path from the brake calipers to the brake cylinder goes only
> > > > uphill -
> > > > first try to actuate the brake cylinder lever - sometimes this will
> > > > "burp" the air
> > > > bubble up into the brake cylinder - otherwise fill fluid from the
> > > > bottom nipple
> > > > until the air bubble goes into the brake cylinder reservoir - *most
> > > > times the
> > > > air bubble will burp into the reservoir and no filling is necessary -
> > > > good luck,
> > > > Ralph Woodward- Hide quoted text -
>
> > > - Show quoted text -
>
> > Changing the fluid every 6 or 8 years is a very good idea. I checked
> > my system last year by having a helper (wife) pump the master cylinder
> > a few strokes and then hold the pressure as I bled out the pressure at
> > the brake.............just like we did in the 1934 Ford. You wouldn't
> > believe what came out, thick gooey stuff that wasn't even red anymore!
> > I had to repeat this for several cycles before the bled fluid started
> > showing red fluid. I also replace my pads when they show less than
> > 1/8" which can be easuly seen with a flashlight and mirror.
> > Cheers,
> > JJ
>
> I've been unable to get the Duo wheel brake to work as it should. This
> includes removing the entire system (caliper, lines, master cylinder)
> and operating it on the bench with a piece of metal to simulate the
> disc. In this configuration it works great - rock hard "brake pedal."
> But it has to be disassembled to go back in the glider, and there it
> is spongy again, no matter how much or how you bleed it. I thought the
> problem might be partial retraction of the pucks due to temperature
> changes, "potato chipped" disc, or vibration, so installed small
> springs behind the pucks to keep them lightly against the disc. No
> improvement.
>
> It helps to pump up the brake with the stick mounted brake lever if
> you have one, while in the landing pattern. Or cycle the air brakes
> fully if you don't have the stick grip.
>
> Another wheel brake problem with the Duo is a fundamental mechanical
> issue. The force required to cycle the speed brakes all the way open
> to the wheel brake actuation point gets higher as you slow down. While
> flying at pattern speed the spoilers stay open by air pressure, but as
> you slow down on the ground they get heavier as air speed no longer
> helps keep the handle back. With little or no airspeed the amount of
> force required to pull the handle all the way back is considerable,
> with little left over to apply brake.
>
> One solution I've employed for the latter is a long bungee cord that
> pulls back on the spoiler handle. But this has a couple significant
> safety issues that must be addressed. It must not be hooked up until
> landing, and the pilot must then keep his/her hand on the spoiler
> handle. A better procedure is to have the back seater help with the
> pull.- Hide quoted text -
>
> - Show quoted text -

I have had similar problems with the Grob 103, just couldn't get the
air bubble to break loose. You might try tilting the fuselage as far
as possible (away from the brake side), then bleed the brakes. This
might allow the bubble to rise up to the master cylinder.
See you at Parowan,
JJ

[bagmaker]

;807799']On Jan 16, 7:39*pm, Karl Striedieck
wrote:
On Jan 16, 6:05*pm, JJ Sinclair wrote:





On Jan 16, 1:56*pm, Morgan wrote:

This pretty much nails what ended up working for me. *I ended up
removing the whole system from the ship and flushing it forwards and
backwards to make sure there wasn't any old fluid or particles in the
system. *Popped the piston out and inspected it and the cylinder wall
for corrosion and pitting. *Overall things looked pretty good, but it
got a good cleaning while I was in there.

Funny, you'll jump through all sorts of hoops and delays to avoid
doing it the "hard way" and in the end that was the least traumatic
and fastest way to get it to work. *It took me way longer than it
should have, but the upside is that I know my braking system inside an
out now and it is time for new pads as well.

Thanks for the tips.

Morgan

On Jan 16, 9:23*am, rhwoody wrote:

On Jan 11, 12:30*am, Morgan wrote:

Looking for advice on bleeding the brakes on my Duo with the tost 30-9
caliper. *I replaced a shot bleeder valve with a new stahlbus valve,
but after futzing with the system for over an hour, I can't get the
brake to firm up to an acceptable level.

I've tried using a suction device to pull fluid (Dot 4 in the Duo)
down through the line. *I've also gone with my normal old standby of
pushing fluid up through the brake using a syringe. *The Stahlbus
valve is not working as advertised or rather the brake isn't. *The
brake doesn't seem to be creating enough pressure to overcome the
spring tension on the check valve.

The best I've been able to get to so far is a fairly spongy grip on
the rotor. Enough that turning by hand isn't possible, but it doesn't
feel like it would slow you down much when you needed it.

Basically it just doesn't feel like the master cylinder is drawing
fluid in or maybe there is a hidden air bubble.

Any thoughts from the internet hive on the quirks of this beast?
It's certainly been a much greater hassle than I expected. *I'm
guessing at this point that either there is a trick that I don't know
about or something is malfunctioning.

Thanks,

Morgan

Hi All, *I have owned a lot of SH gliders and have had success doing
the following -
unbolt the brake cylinder and raise it up so there is no "loop" in the
brake line -
so the path from the brake calipers to the brake cylinder goes only
uphill -
first try to actuate the brake cylinder lever - sometimes this will
"burp" the air
bubble up into the brake cylinder - otherwise fill fluid from the
bottom nipple
until the air bubble goes into the brake cylinder reservoir - *most
times the
air bubble will burp into the reservoir and no filling is necessary -
good luck,
Ralph Woodward- Hide quoted text -

- Show quoted text -

Changing the fluid every 6 or 8 years is a very good idea. I checked
my system last year by having a helper (wife) pump the master cylinder
a few strokes and then hold the pressure as I bled out the pressure at
the brake.............just like we did in the 1934 Ford. You wouldn't
believe what came out, thick gooey stuff that wasn't even red anymore!
I had to repeat this for several cycles before the bled fluid started
showing red fluid. I also replace my pads when they show less than
1/8" which can be easuly seen with a flashlight and mirror.
Cheers,
JJ

I've been unable to get the Duo wheel brake to work as it should. This
includes removing the entire system (caliper, lines, master cylinder)
and operating it on the bench with a piece of metal to simulate the
disc. In this configuration it works great - rock hard "brake pedal."
But it has to be disassembled to go back in the glider, and there it
is spongy again, no matter how much or how you bleed it. I thought the
problem might be partial retraction of the pucks due to temperature
changes, "potato chipped" disc, or vibration, so installed small
springs behind the pucks to keep them lightly against the disc. No
improvement.

It helps to pump up the brake with the stick mounted brake lever if
you have one, while in the landing pattern. Or cycle the air brakes
fully if you don't have the stick grip.

Another wheel brake problem with the Duo is a fundamental mechanical
issue. The force required to cycle the speed brakes all the way open
to the wheel brake actuation point gets higher as you slow down. While
flying at pattern speed the spoilers stay open by air pressure, but as
you slow down on the ground they get heavier as air speed no longer
helps keep the handle back. With little or no airspeed the amount of
force required to pull the handle all the way back is considerable,
with little left over to apply brake.

One solution I've employed for the latter is a long bungee cord that
pulls back on the spoiler handle. But this has a couple significant
safety issues that must be addressed. It must not be hooked up until
landing, and the pilot must then keep his/her hand on the spoiler
handle. A better procedure is to have the back seater help with the
pull.- Hide quoted text -

- Show quoted text -

I have had similar problems with the Grob 103, just couldn't get the
air bubble to break loose. You might try tilting the fuselage as far
as possible (away from the brake side), then bleed the brakes. This
might allow the bubble to rise up to the master cylinder.
See you at Parowan,
JJ

Old motorcycle trick is to elevate the mastercylinder and lever then cable tie the lever with some pressure overnight. Any microscopic bubbles will come out then.
Sounds like a more serios issue is at foot though

bagger

[Karl Striedieck[_2_]]

On Jan 18, 5:36*pm, bagmaker >
wrote:
> 'JJ Sinclair[_2_ Wrote:
>
>
>
>
>
> > ;807799']On Jan 16, 7:39*pm, Karl Striedieck
> >
> > wrote:-
> > On Jan 16, 6:05*pm, JJ Sinclair wrote:
>
> > -
> > On Jan 16, 1:56*pm, Morgan wrote:-
> > --
> > This pretty much nails what ended up working for me. *I ended up
> > removing the whole system from the ship and flushing it forwards and
> > backwards to make sure there wasn't any old fluid or particles in
> > the
> > system. *Popped the piston out and inspected it and the cylinder
> > wall
> > for corrosion and pitting. *Overall things looked pretty good, but
> > it
> > got a good cleaning while I was in there.--
> > --
> > Funny, you'll jump through all sorts of hoops and delays to avoid
> > doing it the "hard way" and in the end that was the least traumatic
> > and fastest way to get it to work. *It took me way longer than it
> > should have, but the upside is that I know my braking system inside
> > an
> > out now and it is time for new pads as well.--
> > --
> > Thanks for the tips.--
> > --
> > Morgan--
> > --
> > On Jan 16, 9:23*am, rhwoody wrote:--
> > --
> > On Jan 11, 12:30*am, Morgan wrote:--
> > --
> > Looking for advice on bleeding the brakes on my Duo with the tost
> > 30-9
> > caliper. *I replaced a shot bleeder valve with a new stahlbus
> > valve,
> > but after futzing with the system for over an hour, I can't get
> > the
> > brake to firm up to an acceptable level.--
> > --
> > I've tried using a suction device to pull fluid (Dot 4 in the Duo)
> > down through the line. *I've also gone with my normal old standby
> > of
> > pushing fluid up through the brake using a syringe. *The Stahlbus
> > valve is not working as advertised or rather the brake isn't. *The
> > brake doesn't seem to be creating enough pressure to overcome the
> > spring tension on the check valve.--
> > --
> > The best I've been able to get to so far is a fairly spongy grip
> > on
> > the rotor. Enough that turning by hand isn't possible, but it
> > doesn't
> > feel like it would slow you down much when you needed it.--
> > --
> > Basically it just doesn't feel like the master cylinder is drawing
> > fluid in or maybe there is a hidden air bubble.--
> > --
> > Any thoughts from the internet hive on the quirks of this beast?
> > It's certainly been a much greater hassle than I expected. *I'm
> > guessing at this point that either there is a trick that I don't
> > know
> > about or something is malfunctioning.--
> > --
> > Thanks,--
> > --
> > Morgan--
> > --
> > Hi All, *I have owned a lot of SH gliders and have had success
> > doing
> > the following -
> > unbolt the brake cylinder and raise it up so there is no "loop" in
> > the
> > brake line -
> > so the path from the brake calipers to the brake cylinder goes only
> > uphill -
> > first try to actuate the brake cylinder lever - sometimes this will
> > "burp" the air
> > bubble up into the brake cylinder - otherwise fill fluid from the
> > bottom nipple
> > until the air bubble goes into the brake cylinder reservoir - *most
> > times the
> > air bubble will burp into the reservoir and no filling is necessary
> > -
> > good luck,
> > Ralph Woodward- Hide quoted text ---
> > --
> > - Show quoted text ---
> > -
> > Changing the fluid every 6 or 8 years is a very good idea. I checked
> > my system last year by having a helper (wife) pump the master
> > cylinder
> > a few strokes and then hold the pressure as I bled out the pressure
> > at
> > the brake.............just like we did in the 1934 Ford. You wouldn't
> > believe what came out, thick gooey stuff that wasn't even red
> > anymore!
> > I had to repeat this for several cycles before the bled fluid started
> > showing red fluid. I also replace my pads when they show less than
> > 1/8" which can be easuly seen with a flashlight and mirror.
> > Cheers,
> > JJ-
>
> > I've been unable to get the Duo wheel brake to work as it should. This
> > includes removing the entire system (caliper, lines, master cylinder)
> > and operating it on the bench with a piece of metal to simulate the
> > disc. In this configuration it works great - rock hard "brake pedal."
> > But it has to be disassembled to go back in the glider, and there it
> > is spongy again, no matter how much or how you bleed it. I thought the
> > problem might be partial retraction of the pucks due to temperature
> > changes, "potato chipped" disc, or vibration, so installed small
> > springs behind the pucks to keep them lightly against the disc. No
> > improvement.
>
> > It helps to pump up the brake with the stick mounted brake lever if
> > you have one, while in the landing pattern. Or cycle the air brakes
> > fully if you don't have the stick grip.
>
> > Another wheel brake problem with the Duo is a fundamental mechanical
> > issue. The force required to cycle the speed brakes all the way open
> > to the wheel brake actuation point gets higher as you slow down. While
> > flying at pattern speed the spoilers stay open by air pressure, but as
> > you slow down on the ground they get heavier as air speed no longer
> > helps keep the handle back. With little or no airspeed the amount of
> > force required to pull the handle all the way back is considerable,
> > with little left over to apply brake.
>
> > One solution I've employed for the latter is a long bungee cord that
> > pulls back on the spoiler handle. But this has a couple significant
> > safety issues that must be addressed. It must not be hooked up until
> > landing, and the pilot must then keep his/her hand on the spoiler
> > handle. A better procedure is to have the back seater help with the
> > pull.- Hide quoted text -
>
> > - Show quoted text --
>
> > I have had similar problems with the Grob 103, just couldn't get the
> > air bubble to break loose. You might try tilting the fuselage as far
> > as possible (away from the brake side), then bleed the brakes. This
> > might allow the bubble to rise up to the master cylinder.
> > See you at Parowan,
> > JJ
>
> Old motorcycle trick is to elevate the mastercylinder and lever then
> cable tie the lever with some pressure overnight. Any microscopic
> bubbles will come out then.
> Sounds like a more serios issue is at foot though
>
> bagger
>
> --
> bagmaker

My next attempt to get a solid "brake pedal" will be to unmount the
master cylinder and elevate it so that the brake line is as close to
vertical as possible. As it lies in the ship the line is about
horizontal and not much better with the tail raised. I'll try Bagger's
suggestion as well if necessary.

KS

[Morgan[_2_]]

On Jan 18, 6:44*pm, Karl Striedieck >
wrote:
> On Jan 18, 5:36*pm, bagmaker >
> wrote:
>
>
>
>
>
>
>
>
>
> > 'JJ Sinclair[_2_ Wrote:
>
> > > ;807799']On Jan 16, 7:39*pm, Karl Striedieck
> > >
> > > wrote:-
> > > On Jan 16, 6:05*pm, JJ Sinclair wrote:
>
> > > -
> > > On Jan 16, 1:56*pm, Morgan wrote:-
> > > --
> > > This pretty much nails what ended up working for me. *I ended up
> > > removing the whole system from the ship and flushing it forwards and
> > > backwards to make sure there wasn't any old fluid or particles in
> > > the
> > > system. *Popped the piston out and inspected it and the cylinder
> > > wall
> > > for corrosion and pitting. *Overall things looked pretty good, but
> > > it
> > > got a good cleaning while I was in there.--
> > > --
> > > Funny, you'll jump through all sorts of hoops and delays to avoid
> > > doing it the "hard way" and in the end that was the least traumatic
> > > and fastest way to get it to work. *It took me way longer than it
> > > should have, but the upside is that I know my braking system inside
> > > an
> > > out now and it is time for new pads as well.--
> > > --
> > > Thanks for the tips.--
> > > --
> > > Morgan--
> > > --
> > > On Jan 16, 9:23*am, rhwoody wrote:--
> > > --
> > > On Jan 11, 12:30*am, Morgan wrote:--
> > > --
> > > Looking for advice on bleeding the brakes on my Duo with the tost
> > > 30-9
> > > caliper. *I replaced a shot bleeder valve with a new stahlbus
> > > valve,
> > > but after futzing with the system for over an hour, I can't get
> > > the
> > > brake to firm up to an acceptable level.--
> > > --
> > > I've tried using a suction device to pull fluid (Dot 4 in the Duo)
> > > down through the line. *I've also gone with my normal old standby
> > > of
> > > pushing fluid up through the brake using a syringe. *The Stahlbus
> > > valve is not working as advertised or rather the brake isn't. *The
> > > brake doesn't seem to be creating enough pressure to overcome the
> > > spring tension on the check valve.--
> > > --
> > > The best I've been able to get to so far is a fairly spongy grip
> > > on
> > > the rotor. Enough that turning by hand isn't possible, but it
> > > doesn't
> > > feel like it would slow you down much when you needed it.--
> > > --
> > > Basically it just doesn't feel like the master cylinder is drawing
> > > fluid in or maybe there is a hidden air bubble.--
> > > --
> > > Any thoughts from the internet hive on the quirks of this beast?
> > > It's certainly been a much greater hassle than I expected. *I'm
> > > guessing at this point that either there is a trick that I don't
> > > know
> > > about or something is malfunctioning.--
> > > --
> > > Thanks,--
> > > --
> > > Morgan--
> > > --
> > > Hi All, *I have owned a lot of SH gliders and have had success
> > > doing
> > > the following -
> > > unbolt the brake cylinder and raise it up so there is no "loop" in
> > > the
> > > brake line -
> > > so the path from the brake calipers to the brake cylinder goes only
> > > uphill -
> > > first try to actuate the brake cylinder lever - sometimes this will
> > > "burp" the air
> > > bubble up into the brake cylinder - otherwise fill fluid from the
> > > bottom nipple
> > > until the air bubble goes into the brake cylinder reservoir - *most
> > > times the
> > > air bubble will burp into the reservoir and no filling is necessary
> > > -
> > > good luck,
> > > Ralph Woodward- Hide quoted text ---
> > > --
> > > - Show quoted text ---
> > > -
> > > Changing the fluid every 6 or 8 years is a very good idea. I checked
> > > my system last year by having a helper (wife) pump the master
> > > cylinder
> > > a few strokes and then hold the pressure as I bled out the pressure
> > > at
> > > the brake.............just like we did in the 1934 Ford. You wouldn't
> > > believe what came out, thick gooey stuff that wasn't even red
> > > anymore!
> > > I had to repeat this for several cycles before the bled fluid started
> > > showing red fluid. I also replace my pads when they show less than
> > > 1/8" which can be easuly seen with a flashlight and mirror.
> > > Cheers,
> > > JJ-
>
> > > I've been unable to get the Duo wheel brake to work as it should. This
> > > includes removing the entire system (caliper, lines, master cylinder)
> > > and operating it on the bench with a piece of metal to simulate the
> > > disc. In this configuration it works great - rock hard "brake pedal."
> > > But it has to be disassembled to go back in the glider, and there it
> > > is spongy again, no matter how much or how you bleed it. I thought the
> > > problem might be partial retraction of the pucks due to temperature
> > > changes, "potato chipped" disc, or vibration, so installed small
> > > springs behind the pucks to keep them lightly against the disc. No
> > > improvement.
>
> > > It helps to pump up the brake with the stick mounted brake lever if
> > > you have one, while in the landing pattern. Or cycle the air brakes
> > > fully if you don't have the stick grip.
>
> > > Another wheel brake problem with the Duo is a fundamental mechanical
> > > issue. The force required to cycle the speed brakes all the way open
> > > to the wheel brake actuation point gets higher as you slow down. While
> > > flying at pattern speed the spoilers stay open by air pressure, but as
> > > you slow down on the ground they get heavier as air speed no longer
> > > helps keep the handle back. With little or no airspeed the amount of
> > > force required to pull the handle all the way back is considerable,
> > > with little left over to apply brake.
>
> > > One solution I've employed for the latter is a long bungee cord that
> > > pulls back on the spoiler handle. But this has a couple significant
> > > safety issues that must be addressed. It must not be hooked up until
> > > landing, and the pilot must then keep his/her hand on the spoiler
> > > handle. A better procedure is to have the back seater help with the
> > > pull.- Hide quoted text -
>
> > > - Show quoted text --
>
> > > I have had similar problems with the Grob 103, just couldn't get the
> > > air bubble to break loose. You might try tilting the fuselage as far
> > > as possible (away from the brake side), then bleed the brakes. This
> > > might allow the bubble to rise up to the master cylinder.
> > > See you at Parowan,
> > > JJ
>
> > Old motorcycle trick is to elevate the mastercylinder and lever then
> > cable tie the lever with some pressure overnight. Any microscopic
> > bubbles will come out then.
> > Sounds like a more serios issue is at foot though
>
> > bagger
>
> > --
> > bagmaker
>
> My next attempt to get a solid "brake pedal" will be to unmount the
> master cylinder and elevate it so that the brake line is as close to
> vertical as possible. As it lies in the ship the line is about
> horizontal and not much better with the tail raised. I'll try Bagger's
> suggestion as well if necessary.
>
> KS

That's the tactic I finally chose. The biggest hassle is dealing with
the handbrake cables when you reconnect them, but total time to pull
the master cylinder was only a few minutes. Excluding the seat
removal, but I already had that out for cleaning the glider for it's
annual. With the master cylinder free and practically a vertical run
from the caliper to the master cylinder, I was able to get good
pressure and a firm pedal, but I'll see tomorrow when I get the new
pads installed and can properly adjust the brake throw with the dive
brakes.

I've always had powerful brakes on my Duo until the last time I flew
it and they were a bit spongy. Just felt like they needed bleeding
though.

I've certainly learned way more about the braking system in the Duo
than I'd thought I'd need to know for a "simple" bleeding job.

[Dan Marotta]

<Lots of snippage>


> Old motorcycle trick is to elevate the mastercylinder and lever then
> cable tie the lever with some pressure overnight. Any microscopic
> bubbles will come out then.
> Sounds like a more serios issue is at foot though
>
> bagger
>
>
>
>
> --
> bagmaker

Does air dissolve in brake fluid? Wouldn't pressurizing the system
overnight cause the air bubbles to dissolve only to come out later after the
pressure is relieved? This is the reason for decompression during deep
dives.

My glider has a mechanical brake (which works quite well, thank you), but on
my motorcycles, I service the brakes with an oil can full of brake fluid. I
draw off as much fluid as I can from the master cylinder and then, using the
oil can, pump it up from the bleed valve at the caliper. It's pretty easy
on the bike to remove the caliper and hold it so that the hose is at the
top, allowing the air to go up the brake line to the master cylinder where
it'll escape as a bubble.

[Three Uniform]

I have nearly the same problem on my V2C. 2 seasons ago I noticed
something dripping from the vent hole in the bottom of the fuselage.
Until then my brake had been rock hard. Inspection showed that yellow
brake fluid was leaking from the master cylinder and gum had formed
around the master. Fluid probably 14 years old. I could not find a
revision set and decided to buy a new Magura master (from the
motorcycle store, used on many BMWs). Instead of a 20mm master, I got
a 16mm master.
The 16mm master should only give a bit more travel. Re-installed and
had the same described spongyness. Took the Cleveland caliper apart
and observed significant corrosion on the caliper, less on the piston.
Sanded carefully a bit, installed new O-ring and re-mounted. Still the
spongyness, even after pumping a pint of new clean fluid both ways (up
and down).
Part of the problem is that the piston retracts a bit upon release of
the brake handle, instead of taking new fluid from the master
reservoir to fill the void.
I need to do more work before the season starts

Question to Bumper:
Can the brass liners and anodized piston be retrofitted ?
Where ?

3U

[Craig[_2_]]

On Jan 23, 10:03*pm, Three Uniform > wrote:
> I have nearly the same problem on my V2C. 2 seasons ago I noticed
> something dripping from the vent hole in the bottom of the fuselage.
> Until then my brake had been rock hard. Inspection showed that yellow
> brake fluid was leaking from the master cylinder and gum had formed
> around the master. Fluid probably 14 years old. I could not find a
> revision set and decided to buy a new Magura master (from the
> motorcycle store, used on many BMWs). Instead of a 20mm master, I got
> a 16mm master.
> The 16mm master should only give a bit more travel. Re-installed and
> had the same described spongyness. Took the Cleveland caliper apart
> and observed significant corrosion on the caliper, less on the piston.
> Sanded carefully a bit, installed new O-ring and re-mounted. Still the
> spongyness, even after pumping a pint of new clean fluid both ways (up
> and down).
> Part of the problem is that the piston retracts a bit upon release of
> the brake handle, instead of taking new fluid from the master
> reservoir to fill the void.
> I need to do more work before the season starts
>
> Question to Bumper:
> Can the brass liners and anodized piston be retrofitted ?
> Where ?
>
> 3U

I saved this link last time Bumper recommended it.
http://www.brakecylinder.com/index.htm

Good luck with the brakes. You may want to look at replacing the
brake line. The one SH used was disintegrating & the brake works much
better after replacing it with a stainless braided unit. The Hot Rod
crowd has great sources.

http://www.jegs.com/i/JEGS-Performance-Products/555/635153/10002/-1?parentProductId=1117442
http://www.jegs.com/webapp/wcs/stores/servlet/KeywordSearchCmd?storeId=10001&catalogId=10002&langId=-1&Ntk=all&Jnar=0&Ne=1%2B2%2B3%2B13%2B1147708&searchTerm=670501

Cheers,
Craig

[Three Uniform]

Changing topic to "problems with Cleveland Brake Calipers"

Thanks Craig for posting Bumpers's link again.
I called Joe at Sierra Specialty Automotive (brakecylinder.com)
He stated that his insurance company does not allow him anymore to
work on aviation parts.
(The part could of course be from a historic tractor)

But more importantly, he concluded that the composition of the
aviation alloys does not match with his process and procedures of
fitting sleeves.
He had to deal with a number of returns.
So, he is not providing this service anymore.

In talking to Joe, another point came up.
The Cleveland caliper has the O-ring on the piston.
The sealing is against the bore in the caliper.
Therefore the surface of the piston is not that relevant, but the
condition of the bore is very much so.
In his opinion, the bore should have a polished finish.
When I dis-assembled mine, it definitely did not have a polished
finish.
Apart from some corrosion, there seemed to be a fine, regular, ringed
structure in the surface of the bore.

Any ideas on this ?

3U

[Dan Marotta]

Brake cylinder hone?


"Three Uniform" > wrote in message
...
>
> Changing topic to "problems with Cleveland Brake Calipers"
>
> Thanks Craig for posting Bumpers's link again.
> I called Joe at Sierra Specialty Automotive (brakecylinder.com)
> He stated that his insurance company does not allow him anymore to
> work on aviation parts.
> (The part could of course be from a historic tractor)
>
> But more importantly, he concluded that the composition of the
> aviation alloys does not match with his process and procedures of
> fitting sleeves.
> He had to deal with a number of returns.
> So, he is not providing this service anymore.
>
> In talking to Joe, another point came up.
> The Cleveland caliper has the O-ring on the piston.
> The sealing is against the bore in the caliper.
> Therefore the surface of the piston is not that relevant, but the
> condition of the bore is very much so.
> In his opinion, the bore should have a polished finish.
> When I dis-assembled mine, it definitely did not have a polished
> finish.
> Apart from some corrosion, there seemed to be a fine, regular, ringed
> structure in the surface of the bore.
>
> Any ideas on this ?
>
> 3U

[Craig[_2_]]

On Jan 24, 3:55*pm, "Dan Marotta" > wrote:
> Brake cylinder hone?
>
> "Three Uniform" > wrote in message
>
> ....
>
>
>
>
>
>
>
>
>
> > Changing topic to "problems with Cleveland Brake Calipers"
>
> > Thanks Craig for posting Bumpers's link again.
> > I called Joe at Sierra Specialty Automotive (brakecylinder.com)
> > He stated that his insurance company does not allow him anymore to
> > work on aviation parts.
> > (The part could of course be from a historic tractor)
>
> > But more importantly, he concluded that the composition of the
> > aviation alloys does not match with his process and procedures of
> > fitting sleeves.
> > He had to deal with a number of returns.
> > So, he is not providing this service anymore.
>
> > In talking to Joe, another point came up.
> > The Cleveland caliper has the O-ring on the piston.
> > The sealing is against the bore in the caliper.
> > Therefore the surface of the piston is not that relevant, but the
> > condition of the bore is very much so.
> > In his opinion, the bore should have a polished finish.
> > When I dis-assembled mine, it definitely did not have a polished
> > finish.
> > Apart from some corrosion, there seemed to be a fine, regular, ringed
> > structure in the surface of the bore.
>
> > Any ideas on this ?
>
> > 3U

I don't think I'd go there unless there is leakage from around the O-
ring. Too much potential for things to go backwards and not much
potential for improvement. The bore surface shouldn't influence how
firm the braking is.

I'd spend my time chasing out:

1. air in the system
2. soft or decayed brake hose
3. flex in the cable bowden leading to the master cylinder

Just my 2 cents,
Craig

[Craig[_2_]]

On Jan 24, 8:15*am, Craig > wrote:
> On Jan 23, 10:03*pm, Three Uniform > wrote:
>
>
>
>
>
>
>
>
>
> > I have nearly the same problem on my V2C. 2 seasons ago I noticed
> > something dripping from the vent hole in the bottom of the fuselage.
> > Until then mybrakehad been rock hard. Inspection showed that yellow
> >brakefluid was leaking from the master cylinder and gum had formed
> > around the master. Fluid probably 14 years old. I could not find a
> > revision set and decided to buy a new Magura master (from the
> > motorcycle store, used on many BMWs). Instead of a 20mm master, I got
> > a 16mm master.
> > The 16mm master should only give a bit more travel. Re-installed and
> > had the same described spongyness. Took the Cleveland caliper apart
> > and observed significant corrosion on the caliper, less on the piston.
> > Sanded carefully a bit, installed new O-ring and re-mounted. Still the
> > spongyness, even after pumping a pint of new clean fluid both ways (up
> > and down).
> > Part of the problem is that the piston retracts a bit upon release of
> > thebrakehandle, instead of taking new fluid from the master
> > reservoir to fill the void.
> > I need to do more work before the season starts
>
> > Question to Bumper:
> > Can the brass liners and anodized piston be retrofitted ?
> > Where ?
>
> > 3U
>
> I saved this link last time Bumper recommended it.http://www.brakecylinder.com/index.htm
>
> Good luck with the brakes. *You may want to look at replacing thebrakeline. *The one SH used was disintegrating & thebrakeworks much
> better after replacing it with a stainless braided unit. *The Hot Rod
> crowd has great sources.
>
> http://www.jegs.com/i/JEGS-Performance-Products/555/635153/10002/-1?p...http://www.jegs.com/webapp/wcs/stores/servlet/KeywordSearchCmd?storeI...
>
> Cheers,
> Craig

Just came across this tool for brakes on ebay.
http://www.ebay.com/itm/Pressure-Brake-Bleeder-Aircraft-Aviation-Car-Truck-Motorcycle-ATV-/270911560043?pt=Motors_Aviation_Parts_Gear&vxp=mtr&hash=item3f1396596b

No association with the seller at all.

Craig Funston

[Karl Striedieck[_2_]]

On Feb 15, 2:47*pm, Craig > wrote:
> On Jan 24, 8:15*am, Craig > wrote:
>
>
>
>
>
> > On Jan 23, 10:03*pm, Three Uniform > wrote:
>
> > > I have nearly the same problem on my V2C. 2 seasons ago I noticed
> > > something dripping from the vent hole in the bottom of the fuselage.
> > > Until then mybrakehad been rock hard. Inspection showed that yellow
> > >brakefluid was leaking from the master cylinder and gum had formed
> > > around the master. Fluid probably 14 years old. I could not find a
> > > revision set and decided to buy a new Magura master (from the
> > > motorcycle store, used on many BMWs). Instead of a 20mm master, I got
> > > a 16mm master.
> > > The 16mm master should only give a bit more travel. Re-installed and
> > > had the same described spongyness. Took the Cleveland caliper apart
> > > and observed significant corrosion on the caliper, less on the piston..
> > > Sanded carefully a bit, installed new O-ring and re-mounted. Still the
> > > spongyness, even after pumping a pint of new clean fluid both ways (up
> > > and down).
> > > Part of the problem is that the piston retracts a bit upon release of
> > > thebrakehandle, instead of taking new fluid from the master
> > > reservoir to fill the void.
> > > I need to do more work before the season starts
>
> > > Question to Bumper:
> > > Can the brass liners and anodized piston be retrofitted ?
> > > Where ?
>
> > > 3U
>
> > I saved this link last time Bumper recommended it.http://www.brakecylinder.com/index.htm
>
> > Good luck with the brakes. *You may want to look at replacing thebrakeline. *The one SH used was disintegrating & thebrakeworks much
> > better after replacing it with a stainless braided unit. *The Hot Rod
> > crowd has great sources.
>
> >http://www.jegs.com/i/JEGS-Performance-Products/555/635153/10002/-1?p.......
>
> > Cheers,
> > Craig
>
> Just came across this tool for brakes on ebay.http://www.ebay.com/itm/Pressure-Brake-Bleeder-Aircraft-Aviation-Car-...
>
> No association with the seller at all.
>
> Craig Funston

A method for bleeding the Duo wheel brake may be found on the Soaring
Cafe at http://soaringcafe.com/2012/01/duo-discus-wheel-brake-adjustment/