<VV> Corvair content, Really! (brakes)

Ramon Rodriguez III corvairgrymm at gmail.com
Wed Mar 23 12:24:03 EDT 2011


On Wed, Mar 23, 2011 at 8:45 AM, John O'Shea <jco99 at cox.net> wrote:

> Wasn't it determined recently here on VV that there is no shuttle valve on
> 67 and up Corvair dual master cylinder brake systems?  Didn't somebody saw
> apart one of those brass housings and prove absolutely, positively that
> there's no valve in there, just a brake light switch?  The Corvair brake
> shuttle valve myth has been around for a long time and may never die, but
> not perpetuating the myth here on VV would be helpful.
>
>
I just searched the archives and couldn't find where anyone had actually cut
one open. (it was a little tricky to follow as part of the convo was
apparently on fastvairs)  There was a post with a bunch of pictures of the
outside of the unit and someone made a statement that it is definitely just
a switch but I don't know on what basis.  I don't really see how you could
say for sure without seeing the inside.

The other thing that was mentioned is that the 67 up pedal assembly is
different, which leaves the question of whether or not there is more total
travel in the later systems.  I have seen several mentions of a factory 69'
setup failing in the same way many of us have experienced with the
conversion kits.  This indicates that even IF there is a difference (shuttle
valve or pedal travel) the pedal adjustment is probably critical.

I think it is VERY important that we pursue this subject and get a final
solid conclusion.  I know of at least one person who had installed a Dual MC
conversion kit and wrecked a vair because he had zero brakes when one half
of the system failed.  I had this happen to me with my conversion kit but it
was during a low speed test drive and the parking brake sufficed to stop me
safely.


Here is what I can do:  I have since adjusted the pedal way up on the 63
with the dual MC conversion kit installed.  I will (not today, 6" of snow
out there right now!) open a front bleeder (simulated broken line) and try
to stop the car.  I will then bleed etc. and open a rear bleeder and repeat
the test.  I know that before I adjusted the pedal height I had absolutely
ZERO brakes with either half of the system open.

Here is what I need someone else to do:  I need someone with a factory 69
setup willing to do the same tests.  If the tester finds very little or no
brakes when they do this adjust the pedal way up and try again to compare
results.  It would also be really great if someone could find out the travel
that a 67+ pedal assembly applies to the MC compared to earlier pedal
assemblies.


We need to get this done so we can properly inform the community as to what
to expect from their Dual MC and to adjust the pedal if it makes any
difference.  I'd also say that if we find anything conclusive and useful we
could suggest the vendors supply a little note with the conversion kits.

Why shell out the dough for a Dual-MC if it behaves just like a single?
(that is what happened to me and many others).


Ray "Grymm" Rodriguez


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