[928uk] Clutch master cylinder

Tue Jan 21 11:31:32 UTC 2025

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
> >>>
>
>