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RE: Silicone Brk. Fluid

To: <healeys@autox.team.net>
Subject: RE: Silicone Brk. Fluid
From: "Jim LeBlanc" <jleblanc@midsouth.rr.com>
Date: Mon, 30 May 2005 20:32:59 -0500
In reply to an inquiry I will openly post an answer. 

This problem I describe with silicone brake fluid applies only to 100-4's,
as far as I know.  

The problem I noticed was dragging of the wheels with overheating of the
brake drums. Upon inspection I noted the master cylinder was failing to
release fluid. The pedal height and play at the push rod were excessive. The
piston was sticking. Also the brake lights stayed on. (pressure in the
system) 

According to Roger Moment's article, the piston must release an additional
0.062 inches to permit the master cylinder bleed holes to operate. 

To accomplish this, the pusher piece needs to be machined to remove 0.062
inch. The pusher piece is the first part behind the push rod and first
inside the retaining clip. See an exploded view of the master cylinder. 

Best Regards, 

Jim LeBlanc
1956 100-M 

-----Original Message-----
From: Jim LeBlanc [mailto:jleblanc@midsouth.rr.com] 
Sent: Monday, May 30, 2005 1:46 PM
To: 'healeys@autox.team.net'
Cc: 'acmiller@mhcable.com'
Subject: RE: Silicone Brk. Fluid


Hi Allen and List: 

I am catching this thread late. 

When converting a car to silicone brake fluid, know that the 6 cylinder and
4 cylinder models are different due to the master cylinders being different.


On this subject, Roger Moment wrote the defining article in the Austin
Healey Magazine, 12/03. 

The 100-4 master cylinder needs a minor modification as documented in that
article. Also White Post knows how to make this modification, well worth the
dollars to send to them for a rebuild. 

Best Regards, 

Jim LeBlanc
-----Original Message-----
From: owner-healeys@autox.team.net [mailto:owner-healeys@autox.team.net] On
Behalf Of Mark and Kathy
Sent: Monday, May 30, 2005 8:06 AM
To: healeys@autox.team.net
Subject: Re: Silicone Brk. Fluid

In my findings the consensus has been to replace ALL rubber seals.  This is 
a decision best done after a complete brake job, including rubber seals.

You can just flush the system and it may work for awhile, but chances are it

will create problems down the road.

My experience was that the silicone tended to cause the rubbers to swell 
excessively when I just flushed the old system.  The wheel cylinders became 
too firm with VERY HARD brake peddle.   Only the front disc brakes were 
working.  So instead of improving my braking it made things much worst.

I have run silicone in many of my cars and have had good results also.    I 
suggest that you use a well know companies product and change ALL your 
rubbers and it should last for a long time.  Remember that this stuff costs 
twice as much as Dot 4 so one leaky seal is money down the drain.

And as I have mentioned on the list before, silicone will also swell the 
seals in an Easy Bleed system over time and makes the seals unusable.    I 
learned that the hard , expensive way.

MARK
----- Original Message ----- 
From: "Allen C Miller, Jr." <acmiller@mhcable.com>
To: <healeys@autox.team.net>
Sent: Monday, May 30, 2005 4:30 AM
Subject: lubricants


> Thanks for the several replies on this thread
>
> If I should go to the silicone brake fluid, how do you convert from
> conventional fluid to silicone? The reservoir is empty, but I have regular
> brake fluid in the lines. Can you just displace the DOT3/4 by filling and
> bleeding in the correct order until you've cylced through a certain amount

> of
> new  silicone fluid? Or do you have to flush out the lines?
>
> Allen 




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