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Grob 103 Twin II Brake Master Cylinder



 
 
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  #1  
Old October 22nd 08, 12:30 PM posted to rec.aviation.soaring
Mike McCarron
external usenet poster
 
Posts: 10
Default Grob 103 Twin II Brake Master Cylinder

My club has a 1983 Grob 103 Twin II that needs a new master cylinder. Over
the years the Grob factory has made changes to the system without full
documentation and as a result the US distributor can not be sure of how I
go about purchasing the proper master cylinder for this glider.

If you or anyone you know has replaced the master cylinder on a vintage
Grob 103 Twin II recently I would appreciate your input on where I might
purchase the correct system.

Thank you,

Mike

  #2  
Old October 22nd 08, 02:41 PM posted to rec.aviation.soaring
JJ Sinclair
external usenet poster
 
Posts: 388
Default Grob 103 Twin II Brake Master Cylinder

If memory serves me, its a motorcycle master cylinder BMW? I believe
they cut it down from the original, good luck getting your inspector
to sign off on installing it!
JJ

Mike McCarron wrote:
My club has a 1983 Grob 103 Twin II that needs a new master cylinder. Over
the years the Grob factory has made changes to the system without full
documentation and as a result the US distributor can not be sure of how I
go about purchasing the proper master cylinder for this glider.

If you or anyone you know has replaced the master cylinder on a vintage
Grob 103 Twin II recently I would appreciate your input on where I might
purchase the correct system.

Thank you,

Mike

  #3  
Old October 22nd 08, 03:00 PM posted to rec.aviation.soaring
Mike McCarron[_2_]
external usenet poster
 
Posts: 47
Default Grob 103 Twin II Brake Master Cylinder

JJ,

I did purchase a master cylinder from a BMW motorcycle dealer that did fit
in place. Unfortunately it did not function properly. It was properly
bled and all but it did not work. I don't know what to do next. There
must be at least 100 of these gliders in the US that will need a master
cylinder replacement in the future. I don't see how we can junk a $30K
glider for lack of a functioning master cylinder.

Thanks for your comment,

MC

At 13:41 22 October 2008, JJ Sinclair wrote:
If memory serves me, its a motorcycle master cylinder BMW? I believe
they cut it down from the original, good luck getting your inspector
to sign off on installing it!
JJ

Mike McCarron wrote:
My club has a 1983 Grob 103 Twin II that needs a new master cylinder.

Over
the years the Grob factory has made changes to the system without full
documentation and as a result the US distributor can not be sure of

how
I
go about purchasing the proper master cylinder for this glider.

If you or anyone you know has replaced the master cylinder on a

vintage
Grob 103 Twin II recently I would appreciate your input on where I

might
purchase the correct system.

Thank you,

Mike


  #4  
Old October 22nd 08, 03:22 PM posted to rec.aviation.soaring
JJ Sinclair
external usenet poster
 
Posts: 388
Default Grob 103 Twin II Brake Master Cylinder

Why didn't it work, Mike? Hydraulics are hydraulics, the Clevland
brake slave cylinder doesn't know (or care) where that pressure is
coming from? Make sure you have compatible seals. What type fluid does
BMW use? Can't mix the red stuff with the clear stuff.
JJ

Mike McCarron wrote:
JJ,

I did purchase a master cylinder from a BMW motorcycle dealer that did fit
in place. Unfortunately it did not function properly. It was properly
bled and all but it did not work. I don't know what to do next. There
must be at least 100 of these gliders in the US that will need a master
cylinder replacement in the future. I don't see how we can junk a $30K
glider for lack of a functioning master cylinder.

Thanks for your comment,

MC

At 13:41 22 October 2008, JJ Sinclair wrote:
If memory serves me, its a motorcycle master cylinder BMW? I believe
they cut it down from the original, good luck getting your inspector
to sign off on installing it!
JJ

Mike McCarron wrote:
My club has a 1983 Grob 103 Twin II that needs a new master cylinder.

Over
the years the Grob factory has made changes to the system without full
documentation and as a result the US distributor can not be sure of

how
I
go about purchasing the proper master cylinder for this glider.

If you or anyone you know has replaced the master cylinder on a

vintage
Grob 103 Twin II recently I would appreciate your input on where I

might
purchase the correct system.

Thank you,

Mike


  #5  
Old October 22nd 08, 03:45 PM posted to rec.aviation.soaring
Mike McCarron[_2_]
external usenet poster
 
Posts: 47
Default Grob 103 Twin II Brake Master Cylinder

JJ,

I used Dot 3 fluid with compatible O ring on the slave cylinder. The cap
on the BMW master cylinder said to use DOT 3/4 brake fluid only.

MC

At 14:22 22 October 2008, JJ Sinclair wrote:
Why didn't it work, Mike? Hydraulics are hydraulics, the Clevland
brake slave cylinder doesn't know (or care) where that pressure is
coming from? Make sure you have compatible seals. What type fluid does
BMW use? Can't mix the red stuff with the clear stuff.
JJ

Mike McCarron wrote:
JJ,

I did purchase a master cylinder from a BMW motorcycle dealer that did

fit
in place. Unfortunately it did not function properly. It was

properly
bled and all but it did not work. I don't know what to do next.

There
must be at least 100 of these gliders in the US that will need a

master
cylinder replacement in the future. I don't see how we can junk a

$30K
glider for lack of a functioning master cylinder.

Thanks for your comment,

MC

At 13:41 22 October 2008, JJ Sinclair wrote:
If memory serves me, its a motorcycle master cylinder BMW? I believe
they cut it down from the original, good luck getting your inspector
to sign off on installing it!
JJ

Mike McCarron wrote:
My club has a 1983 Grob 103 Twin II that needs a new master

cylinder.
Over
the years the Grob factory has made changes to the system without

full
documentation and as a result the US distributor can not be sure of

how
I
go about purchasing the proper master cylinder for this glider.

If you or anyone you know has replaced the master cylinder on a

vintage
Grob 103 Twin II recently I would appreciate your input on where I

might
purchase the correct system.

Thank you,

Mike


  #6  
Old October 22nd 08, 04:01 PM posted to rec.aviation.soaring
bumper
external usenet poster
 
Posts: 322
Default Grob 103 Twin II Brake Master Cylinder

Yup, what JJ said. The "red stuff" is Mil Spec 5606 hydraulic oil and is
compatible with Buna-N O-rings and seals. It's also commonly used in the USA
for most small GA aircraft.

DOT automotive brake fluid, the "clear stuff", most often glycol-ether
based, and is compatible with EPDM rubber seals.

If you are switching parts from one fluid to the other, you gotta change the
rubber stuff.

bumper


"JJ Sinclair" wrote in message
...
Why didn't it work, Mike? Hydraulics are hydraulics, the Clevland
brake slave cylinder doesn't know (or care) where that pressure is
coming from? Make sure you have compatible seals. What type fluid does
BMW use? Can't mix the red stuff with the clear stuff.
JJ

Mike McCarron wrote:
JJ,

I did purchase a master cylinder from a BMW motorcycle dealer that did
fit
in place. Unfortunately it did not function properly. It was properly
bled and all but it did not work. I don't know what to do next. There
must be at least 100 of these gliders in the US that will need a master
cylinder replacement in the future. I don't see how we can junk a $30K
glider for lack of a functioning master cylinder.

Thanks for your comment,

MC

At 13:41 22 October 2008, JJ Sinclair wrote:
If memory serves me, its a motorcycle master cylinder BMW? I believe
they cut it down from the original, good luck getting your inspector
to sign off on installing it!
JJ

Mike McCarron wrote:
My club has a 1983 Grob 103 Twin II that needs a new master cylinder.
Over
the years the Grob factory has made changes to the system without full
documentation and as a result the US distributor can not be sure of

how
I
go about purchasing the proper master cylinder for this glider.

If you or anyone you know has replaced the master cylinder on a

vintage
Grob 103 Twin II recently I would appreciate your input on where I

might
purchase the correct system.

Thank you,

Mike



  #7  
Old October 22nd 08, 04:22 PM posted to rec.aviation.soaring
Uncle Fuzzy
external usenet poster
 
Posts: 260
Default Grob 103 Twin II Brake Master Cylinder

On Oct 22, 8:01*am, "bumper" wrote:
Yup, what JJ said. The "red stuff" is Mil Spec 5606 hydraulic oil and is
compatible with Buna-N O-rings and seals. It's also commonly used in the USA
for most small GA aircraft.

DOT automotive brake fluid, the "clear stuff", most often glycol-ether
based, and is compatible with EPDM rubber seals.

If you are switching parts from one fluid to the other, you gotta change the
rubber stuff.

bumper

"JJ Sinclair" wrote in message

...



Why didn't it work, Mike? Hydraulics are hydraulics, the Clevland
brake slave cylinder doesn't know (or care) where that pressure is
coming from? Make sure you have compatible seals. What type fluid does
BMW use? Can't mix the red stuff with the clear stuff.
JJ


Mike McCarron wrote:
JJ,


I did purchase a master cylinder from a BMW motorcycle dealer that did
fit
in place. *Unfortunately it did not function properly. *It was properly
bled and all but it did not work. *I don't know what to do next. *There
must be at least 100 of these gliders in the US that will need a master
cylinder replacement in the future. *I don't see how we can junk a $30K
glider for lack of a functioning master cylinder.


Thanks for your comment,


MC


At 13:41 22 October 2008, JJ Sinclair wrote:
If memory serves me, its a motorcycle master cylinder BMW? I believe
they cut it down from the original, good luck getting your inspector
to sign off on installing it!
JJ


Mike McCarron wrote:
My club has a 1983 Grob 103 Twin II that needs a new master cylinder.

  #8  
Old October 22nd 08, 05:33 PM posted to rec.aviation.soaring
Uncle Fuzzy
external usenet poster
 
Posts: 260
Default Grob 103 Twin II Brake Master Cylinder

On Oct 22, 8:22*am, Uncle Fuzzy wrote:
On Oct 22, 8:01*am, "bumper" wrote:





Yup, what JJ said. The "red stuff" is Mil Spec 5606 hydraulic oil and is
compatible with Buna-N O-rings and seals. It's also commonly used in the USA
for most small GA aircraft.


DOT automotive brake fluid, the "clear stuff", most often glycol-ether
based, and is compatible with EPDM rubber seals.


If you are switching parts from one fluid to the other, you gotta change the
rubber stuff.


bumper


"JJ Sinclair" wrote in message


....


Why didn't it work, Mike? Hydraulics are hydraulics, the Clevland
brake slave cylinder doesn't know (or care) where that pressure is
coming from? Make sure you have compatible seals. What type fluid does
BMW use? Can't mix the red stuff with the clear stuff.
JJ


Mike McCarron wrote:
JJ,


I did purchase a master cylinder from a BMW motorcycle dealer that did
fit
in place. *Unfortunately it did not function properly. *It was properly
bled and all but it did not work. *I don't know what to do next. *There
must be at least 100 of these gliders in the US that will need a master
cylinder replacement in the future. *I don't see how we can junk a $30K
glider for lack of a functioning master cylinder.


Thanks for your comment,


MC


At 13:41 22 October 2008, JJ Sinclair wrote:
If memory serves me, its a motorcycle master cylinder BMW? I believe
they cut it down from the original, good luck getting your inspector
to sign off on installing it!
JJ


Mike McCarron wrote:
My club has a 1983 Grob 103 Twin II that needs a new master cylinder.
Over
the years the Grob factory has made changes to the system without full
documentation and as a result the US distributor can not be sure of
how
I
go about purchasing the proper master cylinder for this glider.


If you or anyone you know has replaced the master cylinder on a
vintage
Grob 103 Twin II recently I would appreciate your input on where I
might
purchase the correct system.


Thank you,


Mike- Hide quoted text -


- Show quoted text -


In our club Grob 103, the master cylinder is a Magura motorcycle front
brake master cylinder. *Magura makes parts for a bunch of bikes, and
for the aftermarket. Motorcycle front brake master cylinders come in a
variety of piston diameters. *They are also somewhat weird to bleed.
They won't develop pressure unless almost all of the air is bled out
of the system. *"Pumping" one endlessly has no effect. *On a bike, one
trick is to zip tie the handle so that the lever is halfway to the
grip, crack the bleeder on the caliper (with a tube on it to direct
the drainage), and walk away for a couple hours and let gravity do
some work for you. *Much quicker is to zip tie the lever halfway, and
use a small vacuum pump rig to PULL the fluid through. *Once most of
the air is gone, you should be able to develop some pressure to
complete the bleeding in the normal manner. *YES to DOT 3/4. *NO to
Mil Spec 5606 hydraulic oil. *As an experiment, I tossed some
motorcycle brake bits in a jar of 5606. *They turned into something
other than brake bits pretty quickly.- Hide quoted text -

- Show quoted text -


Clarification on the quicker way to purge the air out: Zip tie the
lever at half travel, use a vacuum pump ON THE CALIPER BLEEDER to pull
brake fluid through. Hope this helps
  #9  
Old October 22nd 08, 06:00 PM posted to rec.aviation.soaring
Mike McCarron[_2_]
external usenet poster
 
Posts: 47
Default Grob 103 Twin II Brake Master Cylinder

How can one tell where to position the lever? Half way through it's total
travel or some other location?

MC

At 16:33 22 October 2008, Uncle Fuzzy wrote:
On Oct 22, 8:22=A0am, Uncle Fuzzy wrote:
On Oct 22, 8:01=A0am, "bumper" wrote:





Yup, what JJ said. The "red stuff" is Mil Spec 5606 hydraulic oil

and
i=
s
compatible with Buna-N O-rings and seals. It's also commonly used

in
th=
e USA
for most small GA aircraft.


DOT automotive brake fluid, the "clear stuff", most often

glycol-ether
based, and is compatible with EPDM rubber seals.


If you are switching parts from one fluid to the other, you gotta

chang=
e the
rubber stuff.


bumper


"JJ Sinclair" wrote in message



..=

..

Why didn't it work, Mike? Hydraulics are hydraulics, the Clevland
brake slave cylinder doesn't know (or care) where that pressure

is
coming from? Make sure you have compatible seals. What type fluid

doe=
s
BMW use? Can't mix the red stuff with the clear stuff.
JJ


Mike McCarron wrote:
JJ,


I did purchase a master cylinder from a BMW motorcycle dealer

that
d=
id
fit
in place. =A0Unfortunately it did not function properly. =A0It

was
p=
roperly
bled and all but it did not work. =A0I don't know what to do

next.
=
=A0There
must be at least 100 of these gliders in the US that will need a

mas=
ter
cylinder replacement in the future. =A0I don't see how we can

junk
a=
$30K
glider for lack of a functioning master cylinder.


Thanks for your comment,


MC


At 13:41 22 October 2008, JJ Sinclair wrote:
If memory serves me, its a motorcycle master cylinder BMW? I

believ=
e
they cut it down from the original, good luck getting your

inspecto=
r
to sign off on installing it!
JJ


Mike McCarron wrote:
My club has a 1983 Grob 103 Twin II that needs a new master

cylin=
der.
Over
the years the Grob factory has made changes to the system

without=
full
documentation and as a result the US distributor can not be

sure
=
of
how
I
go about purchasing the proper master cylinder for this

glider.

If you or anyone you know has replaced the master cylinder on

a
vintage
Grob 103 Twin II recently I would appreciate your input on

where
=
I
might
purchase the correct system.


Thank you,


Mike- Hide quoted text -


- Show quoted text -


In our club Grob 103, the master cylinder is a Magura motorcycle front
brake master cylinder. =A0Magura makes parts for a bunch of bikes, and
for the aftermarket. Motorcycle front brake master cylinders come in a
variety of piston diameters. =A0They are also somewhat weird to bleed.
They won't develop pressure unless almost all of the air is bled out
of the system. =A0"Pumping" one endlessly has no effect. =A0On a

bike,
on=
e
trick is to zip tie the handle so that the lever is halfway to the
grip, crack the bleeder on the caliper (with a tube on it to direct
the drainage), and walk away for a couple hours and let gravity do
some work for you. =A0Much quicker is to zip tie the lever halfway,

and
use a small vacuum pump rig to PULL the fluid through. =A0Once most of
the air is gone, you should be able to develop some pressure to
complete the bleeding in the normal manner. =A0YES to DOT 3/4. =A0NO

to
Mil Spec 5606 hydraulic oil. =A0As an experiment, I tossed some
motorcycle brake bits in a jar of 5606. =A0They turned into something
other than brake bits pretty quickly.- Hide quoted text -

- Show quoted text -


Clarification on the quicker way to purge the air out: Zip tie the
lever at half travel, use a vacuum pump ON THE CALIPER BLEEDER to pull
brake fluid through. Hope this helps

  #10  
Old October 22nd 08, 06:39 PM posted to rec.aviation.soaring
bumper
external usenet poster
 
Posts: 322
Default Grob 103 Twin II Brake Master Cylinder

Hook up vacuum pot to caliper bleed valve, open valve a turn, apply vacuum,
squeeze lever slowly until fluid flows out of bleed valve. Be sure to add
fluid to reservoir as level drops.

bumper

"Mike McCarron" wrote in message
...
How can one tell where to position the lever? Half way through it's total
travel or some other location?

MC

At 16:33 22 October 2008, Uncle Fuzzy wrote:
On Oct 22, 8:22=A0am, Uncle Fuzzy wrote:
On Oct 22, 8:01=A0am, "bumper" wrote:





Yup, what JJ said. The "red stuff" is Mil Spec 5606 hydraulic oil

and
i=
s
compatible with Buna-N O-rings and seals. It's also commonly used

in
th=
e USA
for most small GA aircraft.

DOT automotive brake fluid, the "clear stuff", most often

glycol-ether
based, and is compatible with EPDM rubber seals.

If you are switching parts from one fluid to the other, you gotta

chang=
e the
rubber stuff.

bumper

"JJ Sinclair" wrote in message


..=

..

Why didn't it work, Mike? Hydraulics are hydraulics, the Clevland
brake slave cylinder doesn't know (or care) where that pressure

is
coming from? Make sure you have compatible seals. What type fluid

doe=
s
BMW use? Can't mix the red stuff with the clear stuff.
JJ

Mike McCarron wrote:
JJ,

I did purchase a master cylinder from a BMW motorcycle dealer

that
d=
id
fit
in place. =A0Unfortunately it did not function properly. =A0It

was
p=
roperly
bled and all but it did not work. =A0I don't know what to do

next.
=
=A0There
must be at least 100 of these gliders in the US that will need a

mas=
ter
cylinder replacement in the future. =A0I don't see how we can

junk
a=
$30K
glider for lack of a functioning master cylinder.

Thanks for your comment,

MC

At 13:41 22 October 2008, JJ Sinclair wrote:
If memory serves me, its a motorcycle master cylinder BMW? I

believ=
e
they cut it down from the original, good luck getting your

inspecto=
r
to sign off on installing it!
JJ

Mike McCarron wrote:
My club has a 1983 Grob 103 Twin II that needs a new master

cylin=
der.
Over
the years the Grob factory has made changes to the system

without=
full
documentation and as a result the US distributor can not be

sure
=
of
how
I
go about purchasing the proper master cylinder for this

glider.

If you or anyone you know has replaced the master cylinder on

a
vintage
Grob 103 Twin II recently I would appreciate your input on

where
=
I
might
purchase the correct system.

Thank you,

Mike- Hide quoted text -

- Show quoted text -

In our club Grob 103, the master cylinder is a Magura motorcycle front
brake master cylinder. =A0Magura makes parts for a bunch of bikes, and
for the aftermarket. Motorcycle front brake master cylinders come in a
variety of piston diameters. =A0They are also somewhat weird to bleed.
They won't develop pressure unless almost all of the air is bled out
of the system. =A0"Pumping" one endlessly has no effect. =A0On a

bike,
on=
e
trick is to zip tie the handle so that the lever is halfway to the
grip, crack the bleeder on the caliper (with a tube on it to direct
the drainage), and walk away for a couple hours and let gravity do
some work for you. =A0Much quicker is to zip tie the lever halfway,

and
use a small vacuum pump rig to PULL the fluid through. =A0Once most of
the air is gone, you should be able to develop some pressure to
complete the bleeding in the normal manner. =A0YES to DOT 3/4. =A0NO

to
Mil Spec 5606 hydraulic oil. =A0As an experiment, I tossed some
motorcycle brake bits in a jar of 5606. =A0They turned into something
other than brake bits pretty quickly.- Hide quoted text -

- Show quoted text -


Clarification on the quicker way to purge the air out: Zip tie the
lever at half travel, use a vacuum pump ON THE CALIPER BLEEDER to pull
brake fluid through. Hope this helps



 




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