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Re: TD Brake Update

Subject: Re: TD Brake Update
From: Bob Howard <>
Date: Fri, 15 Sep 2006 09:47:46 -0400
Hi Bill,
   If confession is good for the soul, there will be several of us in MG
land who will be improved by this MC exercise.
   Yesterday I suggested that the cup wasn't clearing "the" hole, looking
at the M.2 illustration as I wrote.
   Prompted by your message below, I looked more carefully at M.2 ---
there  _are_  two holes, a smaller one above the end of the spring and
the larger one just over the flared area of the pushrod.  It's just a
straight drilling from fluid chamber to the action part of the MC.
   In the text, mention is made of the outlet valve, compensating orifice
and bypass port, and  "without this clearance the main cup will cover the
bypass port, causing pressure to build up within the system, and produce
binding of the brakes on all wheels"   That little drilled hole must be
the bypass port.  
Regardless of its name, it must be open.  I think you have solved the
   BTW, my friendly veterianarian has been kind enough to keep me
supplied with used syringes for brake fluid and other fluid transfer
work, and more recently for precise measurement of epoxy resin parts
during construction of a canoe.  

On Thu, 14 Sep 2006 21:00:05 -0400 <> writes:
> Okay, I feel like an idiot.................but that's nothing new. 
> When a veterinarian tries to become an LBC mechanic, what do you
> I removed the master cylinder this evening, took it apart for
> inspection, meticulously put it back together, and then tried to 
> force fluid back into the MC using a large syringe. (Yes, I used to
> on horses and cows, too.) No go. All I managed to do was blow back 
> fluid all over myself. Then I got out an old MC core that I 
> have........very rusty and inspected the fluid chamber. Lo and behold,
I saw not one, 
> but two orifices where only one is visible on the MC I am using. Yes
> return port is completely corroded shut!. No wonder I can't get 
> fluid return and the brake pressure switch stays on all the time!
> So, I took a small drill bit and poked around until I found the 
> hole. It was really quite invisible, even with my newly necessary
> glasses. Looking into the piston chamber, the wall of the sleeve 
> looks as smooth as a baby's behind except for the fluid supply hole.
> swear there is not even a dimple. Therefore my question:
> Does the return port go straight from the fluid chamber into the 
> piston sleeve, or does it open somewhere else? The one picture I found
> the internal setup of the MC in the workshop manual seems to show that 
> it is just a straight shot. But before I do permanent damage to an 
> otherwise clean (?) MC, I just wanted to check with you guys!
> Thanks again...........and I wouldn't blame anyone for flaming me on
> this one.
> Bill Snyder
> '53 TD

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