[Spridgets] Master cylinder maintenance

[GUY DAY]

Phil,

The way I see it is that you will probably have to replace all your rubbers 
and flush the whole system through.  Methylated spirits would be good to 
start with and move onto which ever fluid you intend using.  If DOT 4 is 
your fluid of choice and DOT 3 is much cheaper it would be DOT 3 for the 
final flush.

In laymans terms (mine) the problem is the molecules of silicone fluid (or 
the ordinary brake fluid) soak into the rubbers then, when you put whichever 
is the other fluid in, that too soaks into the rubbers and a reaction starts 
between the fluids and it this which expands and softens the rubber beyond 
normal tolerances.  One fluid on its own does not have the reaction problem.

Silicone fluid does not have the same degree of lubricating properties that 
ordinary brake fluid has and this may have contributed to the leak if there 
is a slight area of roughness between rubbers and metal.  If you decide to 
strip the master cylinder down spend a little time in evaluating where the 
leak has come from.  If the brakes are well worn you may find either 
adjustment or replacing the braking surfaces may place the master cylinder 
parts working back in the 'normal use' area and the leak stops.  Check for 
rust in the lower areas of the m/cyl and whl/cyls.

Some people have changed over fluids without having to replace rubbers with 
some success but I do feel there is a large element of luck in that process. 
Four years is too much to expect.

Best of luck whichever route you take.

Guy R Day






----- Original Message ----- 
From: "Philip Nase" <nases at verizon.net>
To: "Spridgets at autox.team. Net net" <spridgets at autox.team.net>
Sent: Tuesday, July 10, 2012 8:00 PM
Subject: [Spridgets] Master cylinder maintenance


> I've been using silicone in my Bugeye master for 4 years but I noticed 
> some
> fluid on the pedal pads during a long ride yesterday. The MC rubber I had 
> was
> supposed to be for use with the silicone but maybe 4 years is too much to
> expect.
>
> Anyway if I switch to conventional  fluid what should I flush the system 
> with?
> And do I need to replace anything that is currently ok such as hoses or 
> wheel
> cylinder rubbers?
>
> I initially used the silicone to help save my paint from mishaps but may
> change now.
>
> Thanks.
>
> Phil Nase
> ------------------------
>
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