<VV> brake help

[Steve Gangi]

I'd like to add my two cents as a rubber chemist.  1. When a new rubber seal is exposed to a fluid for the first time it becomes conditioned to that fluid (swells) and takes a set. When that fluid is removed, the rubber slowly recovers (shrinks). DOT 3 brake fluid and Silicone are very different. They do not mix and cause different swelling. Once a brake part has been swelled once in DOT 3 it will not re-swell to the same dimensions in silicone and probably leak. 2. If you are putting silicone into a system previously containing DOT 3 you should at least clean the system with alcohol and dry out completely by blowing compressed air through the lines. Then take apart the cylinders and wipe all the rubber cups off with alcohol. If you are going to go through all that, you might as well put in new rubber cups or new wheel cylinders. I have had similar experiences as many of you; great results with new parts and mixed results taking short cuts. I live near the ocean and silicone is a necessity for old cars. Steve GangiBranford, CT6 Corvairs
Message: 2
Date: Wed, 16 Jan 2019 20:24:52 -0500
From: FrankDuVal <corvairduval at cox.net>
To: virtualvairs at corvair.org
Subject: Re: <VV> brake help
Message-ID: <168464a8-9dad-2b53-6bf3-012b09bca907 at cox.net>
Content-Type: text/plain; charset=utf-8; format=flowed

Just because you tried the DOT 5 in a worn system and it leaked out does 
not mean DOT 5 is a bad product, it means you needed to address the worn 
seals.

If it was the braking system would you have been equally stubborn to fix 
the leaks? "Well, it seems fine now..."

Just being throttle means failure would be inconvenient, not a safety 
problem, but brakes?

Been using DOT 5 for almost 40 years, NO issues. No brake failure due to 
supposed DOT? 5 issues. Nice to have 20 year old wheel cylinders still 
work like when they were rebuilt! No more white corrosion.

Frank DuVal

On 1/16/2019 7:33 PM, Hugo Miller via VirtualVairs wrote:
> I have a coach business in the UK - I used to have a coach with a 
> hydraulic throttle. I switched to silicone fluid, thinking it would be 
> better. It started leaking. As a stop-gap, I just topped it up with 
> conventional fluid till I could replace the seals. As the silicone 
> fluid was replaced (or rather leaked out!) the leak slowed then 
> stopped. I never did replace the seals! Never used the stuff since!
>
>