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