Master Cylinder - WTF?

[kkrup62 at hotmail.com (Karl Krupke)]

Another option is to use a hand-vacuum pump and a bleed setup. I've seen 
kits in parts store that come with the tubing and bottle; one tube from 
bleed nipple to bottle, another tube from the bottle to the pump.
    Pull up a few pounds of vacuum, crack the bleeder, close it when the 
vacuum gets low.
    Doesn't cost a whole lot ($20 -ish?) and works fairly well, allows 
one-person bleeding, and the pump can be used to test the various vacuum 
operated heater flaps and such...

Karl

>From: "Brian Wagner" <dagnamit@gmail.com>
>To: "Dan Bubb" <jdbubb@verizon.net>
>CC: scirocco-l@scirocco.org
>Subject: Re: Master Cylinder - WTF?
>Date: Thu, 29 Mar 2007 14:44:41 -0500
>
>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.
>> >
>> >
>> >
>> >
>> >
>>____________________________________________________________________________________
>> > Need Mail bonding?
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>> > http://answers.yahoo.com/dir/?link=list&sid=396546091
>> >
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>> >
>>
>>
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