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MGA Master cylinder

To: MG Mailing List <>
Subject: MGA Master cylinder
From: David Littlefield <>
Date: Sat, 07 Dec 1996 17:37:07 -0800
I posted this to the list a week or so ago and got only one response,
which didn't pan out.  Hopefully, someone out there looking for cat
and MOWOG threads will take pity and answer a technical question;)

I'm rebuilding my master cylinder because my clutch was not holding
hydraulic pressure.

When draining the MC I got fluid mixed with black sludge from
disintegrating seals.  I have been using silicone fluid for almost ten
years with those seals, so I think that is a good run.

My problem is that I can't find the proper replacement seals.  I ordered
the kit from Moss and all the seals fit properly except the two front
(meaning closest to the front of the car) ones.  The ones that came with
the Moss kit are designed to fit behind the front flange on the piston
and over a ridge that is a little behind the flange, which apparently
holds it in place.  My pistons are not shaped that way.  Instead they
have two equal size flanges that the seal fits between.  The second
flange is the same size as the first and the seal is held between them. 
Moss apparently hasn't seen this configuration before and the seal that
came with the kit will *not* fit between the two flanges.  However, the
DPO (not locatable) told me he had replaced all the seals in a rebuild
before I bought it, so he apparently got them somewhere (if he is to be
believed, and there is good reason not to).  I can only think that these
pistons are from an aftermarket MC, now long gone, were a Mk II item
(then why hasn't Moss seen them before?), or came from another British
car altogether.  I *know* the MC is stock MGA because I replaced it
some years ago.

Can anyone help with suggestions as to where to find proper seals?  Or
does anyone have two spare (standard) MGA MC pistons?  They are
unobtainable new.

Below is a crude rendering of my piston:

<Front of car.
Seal goes between the two flanges closest together.  There is exactly
0.25" between them:
__   __         __
| |  | |        | |
| |--| |--------| |
| |--| |--------| |
| |  | |        | |
--   --         --

And this is the one that is apparently standard, looking closely at the
Moss illustration and judging from the look of the seals:

Seal fits over second ridge.
__              __
| |  __         | |
| |--| |--------| |
| |--| |--------| |
| |  --         | |
--              --

Any assistance would be much appreciated.  The car has been sidelined
for this problem and others for a few weeks, now, and I'm getting an
itchy throttle foot.

David Littlefield
Houston, TX

--"Experience is recognizing a mistake the second time you make it"--

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