<VV> brake help

[Frank DuVal]

I can tell you from almost 40 years of DOT 5 use that this internet warning is a bunch of hokum, like most unsubstantiated things one reads on the Internet, HA!

I give real world experience I have with the product. 

Not being hygroscopic is the benefit of DOT 5, not a problem to be reckoned with. If it was, I would have line failure from the inside on my cars sometime during the last almost 40 years. Always rust from the outside in is the cause. 

I will say I never used DOT 5 in a system using DOT 3 without rebuilding the system. Why would I? I’m trying to make a brake system that lasts for years, not pour expensive fluid in with who knows what, including all that d#$& white corrosion that DOT 3 brake systems have after a few years. 

Frank DuVal

> On Jan 23, 2019, at 7:15 PM, Hugo Miller via VirtualVairs <virtualvairs at corvair.org> wrote:
> 
> I presume the significance of your living near the ocean is that there is more moisture in the air? I have heard that since silicone fluid isn't hygroscopic, any moisture in the system will 'pool' at the lowest points & just sit there causing corrosion, rather than mixing with the fluid (where it can be flushed out every time you change brake fluid).
> I have no idea whether that is correct, but to me it is just another reason to be wary of silicone fluid, since its major advantage might in fact be a disadvantage.
> 
> 
> 
>> On 2019-01-23 16:10, Steve Gangi via VirtualVairs wrote:
>> 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
>> ___