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losing rear brake pressure

Started by Smokescreen, August 12, 2014, 05:01:05 PM

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Smokescreen

August 12, 2014, 05:01:05 PM
So there is no leak in my circuit, but my rear brake (S2R1K) once bled, will work for a day and be flat the next day.  I don't use the rear a lot, but I don't like not having it one bit. 

Ideas?

Has anybody experienced this?

Find a solution? 

Is there a rebuild kit for the piston somewhere someone maybe has a link for?
Catching a yellow-jacket in your shirt at seventy miles per hour can double your vocabulary. 

Only a biker knows why a dog sticks his head out of a car window.

Dirty Duc

#1
August 12, 2014, 05:29:50 PM
It can be difficult to get that last air bubble out of the rear brake line.

Smokescreen

#2
August 12, 2014, 05:45:15 PM
I don't think it's a lingerer.  I vacuum bleed and have pressure when I'm done.  the brake works, then the next day it doesn't.  So I'm thinking either it's a leaky crush point, or it's the master cylinder/piston
Catching a yellow-jacket in your shirt at seventy miles per hour can double your vocabulary. 

Only a biker knows why a dog sticks his head out of a car window.

ducpainter

#3
August 12, 2014, 05:57:20 PM
Not uncommon for a Duc rear master to be junk.

No rebuild parts available in the US AFAIK.
"Once you accept that a child on the autistic spectrum experiences the world in
 a completely different way than you, you will be open to understand how that
 perspective
    is even more amazing than yours."
    To realize the value of nine  months:
    Ask a mother who gave birth to a stillborn.
"Don't piss off old people The older we get, the less 'Life in Prison' is a deterrent."


Smokescreen

#4
August 12, 2014, 06:11:29 PM
As far as I can tell, the rear brake is the Brembo PS 11 C.  I've found a rebuild kit in the UK and Germany, but nothing in USa yet. 
Catching a yellow-jacket in your shirt at seventy miles per hour can double your vocabulary. 

Only a biker knows why a dog sticks his head out of a car window.

ducpainter

#5
August 12, 2014, 06:49:30 PM
Quote from: Smokescreen on August 12, 2014, 06:11:29 PM
As far as I can tell, the rear brake is the Brembo PS 11 C.  I've found a rebuild kit in the UK and Germany, but nothing in USa yet. 
We're not smart enough to rebuild a hydraulic brake component. ;)
"Once you accept that a child on the autistic spectrum experiences the world in
 a completely different way than you, you will be open to understand how that
 perspective
    is even more amazing than yours."
    To realize the value of nine  months:
    Ask a mother who gave birth to a stillborn.
"Don't piss off old people The older we get, the less 'Life in Prison' is a deterrent."


brad black

#6
August 12, 2014, 07:24:57 PM
bleed it with the caliper raised, then with it off the disc pump the pads out and push them back a few times.  increase the freeplay at the piston pushrod.
Brad The Bike Boy

http://www.bikeboy.org

SpikeC

#7
August 13, 2014, 09:29:35 AM
 I rebuilt the rear master on my BMW without any problem.
Spike Cornelius
  PDX
   2009 M1100S Assorted blingy odds and ends(now gone)
2008 Bimota DB5R  woo-Hoo!
   1965 T100SC

Smokescreen

#8
August 13, 2014, 08:13:05 PM
I'd still need to be certain that the master is a PS11c, or a PS11b, or something else altogether...
Catching a yellow-jacket in your shirt at seventy miles per hour can double your vocabulary. 

Only a biker knows why a dog sticks his head out of a car window.

Speeddog

#9
August 13, 2014, 08:55:36 PM
Quote from: SpikeC on August 13, 2014, 09:29:35 AM
I rebuilt the rear master on my BMW without any problem.

Which could easily be the case on our Brembo masters, *if* there were parts available.
- - - - - Valley Desmo Service - - - - -
Reseda, CA
(951) 640-8908

~~~ "We've rearranged the deck chairs, refilled the champagne glasses, and the band sounds great. This is fine." - Alberto Puig ~~~

SpikeC

#10
August 13, 2014, 09:03:30 PM
 Well, it was a while ago........
Spike Cornelius
  PDX
   2009 M1100S Assorted blingy odds and ends(now gone)
2008 Bimota DB5R  woo-Hoo!
   1965 T100SC

Howie

#11
August 13, 2014, 10:29:21 PM
Quote from: Smokescreen on August 13, 2014, 08:13:05 PM
I'd still need to be certain that the master is a PS11c, or a PS11b, or something else altogether...

AFIAK there are only two, PS11b and PS11 straight outlet, both come in black or gold.  Anyway, they are not that expensive new if you do not buy it from Ducati.  Contact Fred at  http://www.yoyodyneti.com/contact.aspx  and he will help you out.

ellingly

#12
August 13, 2014, 11:44:13 PM
In terms of this, I sort of have similar but not as bad. Too lazy to throw a new master on and fix my ultimate cause.

In my case, a) you do have to lift the master up and bleed it as per what Brad says, otherwise you do end up with some irritating bubbles. but there's also my issue b) which is that the pushrod from the brake lever is a bit rusty, which has chewed into the seal which means there's perpetually a tiny air leak back through the push rod.

Now, I don't actually care that much about using the rear brake especially when riding really hard, so I live with it. I have a spare master and new pushrod I'll throw on one day. One day.
Team Ghetto Racing: motorcycle racing and riding on a budget
2006 Ducati MS2R1000 road | 1973 Suzuki GT250 cafe race | 1982 Yamaha RD250LC race | 1991 Suzuki GSXR750 perpetual project | 1984 Suzuki TS250x vintage enduro | 1997 Honda CT110 postie of death | 1982 Kawasaki KH100 bucket racer

Speeddog

#13
August 14, 2014, 10:12:48 AM
Quote from: howie on August 13, 2014, 10:29:21 PM
AFIAK there are only two, PS11b and PS11 straight outlet, both come in black or gold.  Anyway, they are not that expensive new if you do not buy it from Ducati.  Contact Fred at  http://www.yoyodyneti.com/contact.aspx  and he will help you out.

+1, as there's no rebuild kits.

You might try a new rubber seal and plastic elbow where the reservoir hose hooks to the master.
I've seen some annoying air leaks there.

Unfortunately, Yoyodyne is no longer a Brembo distributor.
- - - - - Valley Desmo Service - - - - -
Reseda, CA
(951) 640-8908

~~~ "We've rearranged the deck chairs, refilled the champagne glasses, and the band sounds great. This is fine." - Alberto Puig ~~~

ducpainter

#14
August 14, 2014, 10:32:50 AM
Quote from: Speeddog on August 14, 2014, 10:12:48 AM
<snip>

Unfortunately, Yoyodyne is no longer a Brembo distributor.
That isn't very handy.

Who is now?
"Once you accept that a child on the autistic spectrum experiences the world in
 a completely different way than you, you will be open to understand how that
 perspective
    is even more amazing than yours."
    To realize the value of nine  months:
    Ask a mother who gave birth to a stillborn.
"Don't piss off old people The older we get, the less 'Life in Prison' is a deterrent."


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