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Re: Brake Master Cylinder Rebuild

To: Bill Munts <muntsb@HiWAAY.net>
Subject: Re: Brake Master Cylinder Rebuild
From: Martin Libhart <mlibhart@fn.net>
Date: Fri, 08 Nov 1996 14:41:02 +0000
Cc: triumphs@autox.team.net
References: <M.110896.084724.05@max12-78.HiWAAY.net>
Bill Munts wrote:
> 
> Hi Folks,
> 
> I need some wisdom from the early Spitfire guys with cars with tandem master
> cylinders.  I'm having problems with the primary piston seal.  I purchased the
> rebuild kit from Vicky Brit (TRF was out of stock).  The first attempt 
>resulted
> in the primary seal showing a split after I rebuilt the MC and attempted to 
>use
> it.  I called Vicky Brit and they replaced the seal.  The second time around
> the seal split while putting it on.  I'm pretty sure I'm installing it
> correctly, I'm using brake fluid to oil it up and taking my time with it.  I
> can only see one way on with this thing.
> 
> I began to examine the seals (original vs replacement) after I regained my
> composure last night.  The seals are both made in Australia but are marked
> somewhat differently and have different physical dimensions as follows.
> 
> Original =      Marked as 25 P4640
>                 I.D. = .3275"
>                 O.D. = .7450"
>                 Thickness = .2500"
> 
> Replacement =   Marked as 24 P4640
>                 I.D. = .2875"
>                 O.D. = .7400"
>                 Thickness = .2400"
> 
> I can put the original seal on without too much trouble, but the replacement
> simply will not go.  I don't think prolonged exposure to brake fluid would
> account for the original seal having consistently larger dimensions.  My
> experience (professional) with seals in fluid handling show that seals tend to
> grow in one dimension and not equally.  Has anyone else had this same problem?
> Is it likely that VB has the wrong seal in the kit?
> 
> Thanks for your help.
> 
> Bill M.
> '70 Spitfire Mk3

*********************
Bill:

I'll try to do some checking this weekend - if time permits.  I, too, 
have a '70 Spitfire Mk. 3 (the US version), and am pulling out the 
motor & gearbox on Saturday, then blocking the frame and setting up to 
start floor and sill removals/rework over the next few weeks.

If I can at all, I'll look, since I have my original seal, as well as 
a rebuild kit I haven't opened yet.  (I also got the kit from VB.)

Martin Libhart
Wichita, KS
1970 Spitfire-In-Progress

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