Master Cylinder - WTF?

[dagnamit at gmail.com (Brian Wagner)]

It is possible that if he didn't bench bleed the MC he hasn't purged all the
air out of the bore yet. Since they are at a slight upward angle sometime it
is a bitch to remove all the air, the old trick is to jack up the rear only
so the front of the MC is now slightly downward. This allows some of the
trapped air in the bore to filter back into the resivour

On 3/29/07, Patrick Bureau <patrick.bureau@gmail.com> wrote:
>
> Brian, could it be his new master cylinder wasn't bled right (like you did
> mine ?)
>
>
>
> ____
> Patrick Bureau,
> 85 VW Scirocco, 01 Jeep Cherokee, 05 Honda Reflex Sport
> WTB - DFW, Suzuki GS500E/F : http://tinyurl.com/ujc2h
> Reflex Blog : http://reflexscooter.blogspot.com/
>
>
>
> -----Original Message-----
> From: Brian Wagner [mailto:dagnamit@gmail.com]
> Sent: Thursday, March 29, 2007 2:45 PM
> To: Dan Bubb
> Cc: scirocco-l@scirocco.org
> Subject: Re: Master Cylinder - WTF?
>
> Dan,
>
> The theory of stroking does not apply to new or remanufactured (notice I
> didn't say rebuilt). The reason it doesn't hold true on these 2 types is
> the
> complete bore has been stroked to resurface it in preparation for new
> seals.
> So in these 2 types there is no rust accumulation in said bore since they
> were flushed and assembled machine oil.
>
> Now if it was rebuilt you have a problem, rebuilds generally only replace
> the failed part. So if infact a seal was bad on the plunger they only
> replace that, not boring it. Now here is where the problem lies, brake
> fluid
> absorbs moisture right. And we all now that you only stroke 1/2  ~ 3/4 the
> length of the bore. So as rust accumulates in the 1/4 that is left, so if
> you use the pump/hold/floor method the plunger gets into the rusted area.
>
> And since he is installing new I don't think he has that problem.
>
>
> On 3/29/07, Dan Bubb <jdbubb@verizon.net> wrote:
> >
> > Well, just to throw in my >.02.
> > I went through the same thing when installing a new MC on my Scirocco.
> > In the end the MC was replaced under warranty and I bought a power
> > bleeder and never had any problem after that.
> > The assumption was that even a new MC can be damaged stroking it full
> > stroke like you would if you were bleeding the old fashioned way.
> > In your situation the first thing I'd do is run over to Ron's and
> > borrow his power bleeder. ;^) If that doesn't do it then I'd see if
> > the MC can be replaced under warranty.
> > Needless to say the power bleeder is a life saver if you have A3 rear
> > calipers that have to be mounted with the bleeder screw on the bottom.
> > It's still a damn good investment for just about any other bleeding
> situation.
> > Dan
> >
> > From: "Daun Yeagley" <vwdaun@yahoo.com>
> > To: <scirocco-l@scirocco.org>
> > Sent: Wednesday, March 28, 2007 11:31 PM
> > Subject: Master Cylinder - WTF?
> >
> >
> > > As some of you may know, I just installed a new master cylinder on
> > > Deiter, the '81 S.  It seems as though the old one was leaking fluid
> > > into the brake booster.  And yes, I replaced the brake booster with
> > > an unknown quantity used booster.  (Can't seem to get a new one
> > > now.)
> > >
> > > First attempt at bleeding the brakes resulted in the semi-expected
> > > snapped bleeder screws in the rear, so I replaced both wheel
> > > cylinders this evening.
> > >
> > > Filled the brake fluid reservoir and started at the right rear wheel
> > > to work the air out of the system.  I don't have a pressure bleeder,
> > > so I'm stuck with the old "someone pump the pedal while I turn the
> > > bleeder screw" routine.  After working my way around the car, I
> > > still have a brake pedal that shows no real resistance to going to
> > > the floor, AND it seems to have a "catch" in it about 2/3 of the way
> > > down.
> > > (Which was present when I started.)
> > >
> > > So now what?  Have I done something wrong here?
> > >
> > > Daun Yeagley - Wilmington Ohio
> > > '81 Scirocco S (Deiter)       '86 Scirocco 8v
> > > '88 Scirocco Slegato (Gino!)  '88 Scirocco 16v
> > > '96 Passat GLX Wagon          '56 Cessna 172
> > > The first rule of intelligent tinkering is to save all the parts -
> > Ehrlich's Law.
> > >
> > >
> > >
> > >
> > >
> > ______________________________________________________________________
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> > >
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