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Re: MGB Clutch Pedal Hydraulics

Subject: Re: MGB Clutch Pedal Hydraulics
From: (Mark Jurras)
Date: Wed, 19 Apr 1995 08:54:43 -0400
> From Tue Apr 18 19:31 EDT 1995
> X-Msmail-Message-Id:  DA83F67A
> X-Msmail-Conversation-Id:  DA83F67A
> From: Jeff Drexler <>
> My '69 MGB lost all pressure from the clutch pedal at a stoplight 
> yesterday.  The pedal started going mushy the day before.  Since there 
> is no fluid leaking externally from either slave or master cylinder, 
> and since the reservoir is full, I assume an internal seal in one of 
> the cylinders is the problem.  Since one of the two cylinders has to be 
> replaced, does anyone have suggestions on what else should be replaced 
> (or examined) in the clutch hydraulic system.  For example, does it 
> make sense to replace both cylinders, even if one is old but still 
> functioning?  Thanks for any advice.
> Jeff Drexler


Since there is no fluid leaking from the system the leak is most likely
in the Master Cylinder (MC). When the clutch pedal is pressed it causes
the MC to pump more fluid through the lines into the Slave Cylinder (SC).
If the SC leaked the fluid would go past the seals into the dust boot
and drip onto the ground (My problem). If the MC seals are bad the
fluid would leak past them back into the MC reservoir. (The problem
with my brake system).

I hope this makes sense. Now if you are going to repair the MC why not
do the SC since you have it all apart. The SC seal kit only cost me
$2.00 US.

After you rebuild make sure that you use the proper brake fluid. The
MG's were made with natural rubber seals in the hydraulics, most
American brake fluids attack natural rubber. The manual states that
Castrol Girling be used. I use Castrol GT LMA. I've been told it is
compatable. Sombody tell me quick if it isn't. You can also use
Silicone fluid.

Comments Welcome!

Good Luck,

- -Mark       = =o&o

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