[928uk] Clutch master cylinder
Paul R Smith
smiffypr at gmail.com
Tue Jan 21 13:27:43 UTC 2025
Nice picture (saved for future reference).
Could you see what the "bung" is there for?
My '80 one (fixed pre digital cameras) had a one-way valve inside the
piston, which involved a small rubber disk, but I can't remember how the
piston came apart to access that.
Smiffy
On 21/01/2025 12:05, Paul wrote:
I had to do this a few months ago in between track days at the Ring
https://thumbsnap.com/i/MES6LMuz.jpg
I used the kit from PartWorks.de on the right hand side of this photo
https://thumbsnap.com/i/ouDZeMta.jpg
About 12/15 years ago I fitted new seals, but I put the rubber bung on
the left on the wrong way round
https://thumbsnap.com/i/ZJhMFSGK.jpg
So when I took it is apart the bung had split
https://thumbsnap.com/i/pMfzS6j9.jpg
This is the correct way round
https://thumbsnap.com/i/iHFFDXrU.jpg
There was a massive rainstorm that started just before I finished the
job, which was far from ideal
However with the new seals I was able to thoroughly enjoy the second day
on track
https://thumbsnap.com/i/wG1zBVAp.jpg
https://youtu.be/K4y0d98Vzks
Paul
87 S4 Manual
On Tue, 21 Jan 2025 at 11:41, Jonathan Rackowe via 928uk
<928uk at lists.928.org.uk> wrote:
I second that. Replacing the master cylinder is an unnecessary pain when
you can replace its seals without removing the master cylinder and the
associated hoses. Seals are the only parts that wear/fail unless you
allow
water into your brake and clutch fluid.
Best regards,
Jonathan
1991 928 GT Amethyst Metallic
On Tue, 21 Jan 2025, 10:26 am Paul R Smith via 928uk, <
928uk at lists.928.org.uk> wrote:
> Replacing the master cylinder internals can be done from INSIDE THE
> CABIN, so you don't have the difficulties removing and refitting the
> casting from inside the engine bay.
>
> I got a seal set (for my '80) many years ago. It was trivial to
fit (as
> long as you are flexible enough to get your head in the foot
well), but
> I believe there are variations in seal/piston design even with
the same
> porsche part number m/c, so you would probably have to take out your
> piston and measure the seal(s) before ordering to be sure.
>
> It turned out that my problem was not with the m/c anyway. The
bellows
> on the slave were shredded (perished and crumbling), allowing the
> activating rod to vibrate and slowly push the slave piston into it's
> bore, and in mine there was no spring to resist that.
>
> Smiffy
>
> On 21/01/2025 05:17, Simon Crowe via 928uk wrote:
>
> Reading through this topic, it’s great news that the 927 and 928
castings
> are the same . I’ve often wondered this but went with the
significantly
> more expensive 927 M/C a while back.
>
> Replacing the M/c is such a b***h of a job I would recommend only
> replacing with new , even if seals are available. I think I read
a long
> time back somewhere that a M/c kit is available and can be fitted
with the
> casting in place, but having replaced a M/c it’s not a job I
would want to
> regularly do.
>
> > On 20 Jan 2025, at 22:46, jonathanrackowe--- via 928uk<
> 928uk at lists.928.org.uk> wrote:
> >
> > Perhaps it depends on having the right size seal. I rebuilt
the clutch
> slave cylinder for my GT in 2022 and fitting the replacement seal
to the
> piston was no big deal, but getting hold of that seal was a
nightmare as
> Porsche only supply a rebuild kit with a seal for the slave cylinders
> fitted up to 1989 model year.
> >
> > Best regards,
> > Jonathan
> >
> > 1991 928 GT Amethyst Metallic
> >
> >
> >
> >
> >
> > From:jon928se at gmail.com <mailto:From%3Ajon928se at gmail.com>
<jon928se at gmail.com>
> > Sent: 20 January 2025 21:51
> > To:jonathan at rackowe.net <mailto:To%3Ajonathan at rackowe.net>;
'Ben Hodges'<benhodges1975 at gmail.com>
> > Cc: 'Mike Miller'<auskartdyno at gmail.com>; '928 Org'<
> 928uk at lists.928.org.uk>
> > Subject: RE: [928uk] Clutch master cylinder
> >
> >
> >
> > Hi Jonathan
> >
> >
> >
> > Yes I did mean SC. I don’t think rebuild kits are available for
the MC
> but if they were they would probably be equally difficult to fit.
> >
> >
> >
> > Regards
> >
> >
> >
> > Jon
> >
> >
> >
> >
> >
> >
> >
> > From: Jonathan Rackowe <jonathanrackowe at gmail.com <mailto:
> jonathanrackowe at gmail.com> >
> > Sent: 20 January 2025 23:08
> > To: Ben Hodges <benhodges1975 at gmail.com
<mailto:benhodges1975 at gmail.com>
> >
> > Cc: Jon Holdsworth <jon928se at gmail.com
<mailto:jon928se at gmail.com> >;
> Jonathan Rackowe <jonathan at rackowe.net
<mailto:jonathan at rackowe.net> >;
> Mike Miller <auskartdyno at gmail.com <mailto:auskartdyno at gmail.com> >;
> 928 Org <928uk at lists.928.org.uk <mailto:928uk at lists.928.org.uk> >
> > Subject: Re: [928uk] Clutch master cylinder
> >
> >
> >
> > Hi Jon, you wrote about "the rebuild kit for the slave" cyl.
Was that a
> typo? Did you mean the master cylinder or slave cylinder?
> >
> >
> >
> > Best regards
> >
> > Jonathan
> >
> >
> >
> > 1991 928 GT Amethyst Metallic
> >
> >
> >
> >
> >
> >
> >
> > On Mon, 20 Jan 2025, 9:06 am Ben Hodges, <benhodges1975 at gmail.com
> <mailto:benhodges1975 at gmail.com> > wrote:
> >
> > Thanks Jon!
> >
> >
> >
> > On Mon, 20 Jan 2025 at 08:35, <jon928se at gmail.com <mailto:
> jon928se at gmail.com> > wrote:
> >
> > I can't see what the difference is between LHD and RHD master
cylinders,
> the pressure line to the slave comes out of the end of the master
(remote
> from the pedal) on both and the LHD (928 part number, I have two
waiting to
> be fitted) has the supply (infamous blue hose) hose connection
pointing to
> the front of the car. From memory so does the RHD master supply
connection.
> >
> > The only difference I know of is that the push rod connection
to the
> pedal is a ball joint on RHD cars (M8 thread ball joint readily
available
> from non Porsche sources John Speake used to sell them) and is a
rose joint
> type joint on LHD cars because the master lines up better with
the pin (not
> ball) on the pedal. I presume that the rose joint fitting isn’t
M8. If this
> assumption isn't correct this isn't a show stopper as you can
reuse the
> original pushrod.
> >
> > The rebuild kit for the slave is a complete bastard to fit
(primarily
> the pressure seal) and needs to be warmed up in boiling water to
make the
> seal flexible enough to stretch over the piston.
> >
> > Jon
> >
> >
> >
> > -----Original Message-----
> > From: 928uk <928uk-bounces at lists.928.org.uk <mailto:
> 928uk-bounces at lists.928.org.uk> > On Behalf Of Jonathan Rackowe
via 928uk
> > Sent: 20 January 2025 11:04
> > To: Ben Hodges <benhodges1975 at gmail.com
<mailto:benhodges1975 at gmail.com>
> >
> > Cc: Jonathan Rackowe <jonathanrackowe at gmail.com <mailto:
> jonathanrackowe at gmail.com> >; Mike Miller <auskartdyno at gmail.com
> <mailto:auskartdyno at gmail.com> >; 928 Org <928uk at lists.928.org.uk
> <mailto:928uk at lists.928.org.uk> >
> > Subject: Re: [928uk] Clutch master cylinder
> >
> > Hi Ben,
> >
> > Had you already considered new seals?
> >
> > Why do you need to replace the m/c?
> >
> > I would consider a sleeved rhd one nearer to stock than a lhd
one with
> weird hose routing and lengths.
> >
> > If you do replace your m/c please sell one of us the old one to
> recondition.
> >
> > Have you tried Douglas Valley Breakers for a rhd m/c ?
> >
> > Best regards,
> > Jonathan
> >
> > 1991 928 GT Amethyst Metallic
> >
> >
> >> On Sun, 19 Jan 2025, 11:10 pm Ben Hodges via 928uk, <
> 928uk at lists.928.org.uk <mailto:928uk at lists.928.org.uk> >
> >> wrote:
> >>
> >> Thanks Mike
> >>
> >> I’m converting my auto to a manual so want to keep things
stock for
> >> now to minimise the variables!
> >>
> >> Discussing it with a mate earlier he remembered when he put a
new one
> >> into his GT it came with two rods - one being longer than the
other.
> >> I’m going to purchase the 928.xx LHD one and swap the rods
over if it
> >> is a different length.
> >>
> >> Cheers
> >> Ben
> >>
> >>> On Sun, 19 Jan 2025 at 20:50, Mike Miller <auskartdyno at gmail.com
> <mailto:auskartdyno at gmail.com> > wrote:
> >>>
> >>> I had mine stainless steel sleeved and reduces 1 size in
diameter to
> >>> give quicker clutch action. Little adjustment on the assist
spearing
> >>> and pedal effort quite acceptable even for an octanagerian.
> >>> Mike Miller Brisbane 82s 5 sod
> >>>
>
>
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