[928uk] Clutch master cylinder

[Paul]

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  <jon928se at gmail.com>
> > > Sent: 20 January 2025 21:51
> > > To:jonathan 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
> > >>>
> >
> >
>