<VV> brake help

[Hugo Miller]

If the whole system is empty, you have a lot of air to get rid of, and 
it will take time. Just keep going round each wheel & you should 
eventually get a pedal. One word of caution however - if the master 
cylinder has not been rebuilt, you have to be careful not to press the 
pedal more than half-way down. Otherwise the seals will be venturing 
into parts of the bore they have never seen before, where there might be 
corrosion etc that will damage the seals. I've seen many cars with 
rebuilt brake systems (except the master cyl) suffer complete brake 
failure shortly afterwards for this reason. Also, DoT 5 - is that the 
silicone stuff? I hate it! It creeps past seals, and will leak where the 
old fluids do not. If everything is new it might be ok, but it will find 
any worn seals long before the old conventional fluids will - it's like 
the difference between water and anti-freeze.


On 2019-01-16 17:37, JUDY HOOK via VirtualVairs wrote:
> I need some help with the brake system on my newly acquired '69, soon
> to be my new daily driver.  It has the dual master cylinder on it.
> This is my first foray into the world of dual master cylinders.  Last
> evening my wife helped me try and bleed the brakes on said car.  All 
> 4
> wheel cylinders where rebuilt, all 4 rubber hoses replaced, and
> numerous pieces of tubing were replaced in the rear hazardous areas.
> Since I live in PA I decided to try the stainless ones Clark's
> offered.
>
> Since I drove the car home initially, and the brakes seemed to work
> ok, I chose not to rebuild the master cylinder at this point, 
> although
> I did buy a rebuild kit for it, just in case.  I also decided to
> switch this car to the dot 5 brake fluid like my other 2 since I've
> never had a single problem with it.
>
> When prepping the master cylinder for installation, I emptied it as
> much as possible of all old fluid.  I then filled it with the dot 5
> stuff and "bench bled" it with the plastic tubes and cone shaped
> plugs.  You could see the fluid moving thru the tubes.  After
> installation, she pumped and pumped and her foot kept going to the
> floor.  When I would crack a bleeder- nothing.  No rush of air, no
> fluid- nada.  We did that a couple more times with the same results,
> however, this time I noticed the fluid level in the front reservoir
> was down about a half inch.  The rear one never moved.
>
>  This time, when checking the bleeders, I got  a teeny puff of air.
> Then the next time I got a little dripage from it.  But no major
> squirt like you're supposed to get.  There was no resistance at the
> front drum, either.  My wife said her foot kept going to the floor
> with no resistance.
>
> Now, my question is this:  Since you could see the fluid moving thru
> the plastic tubes,  one would assume the master cylinder is pumping
> fluid like it is supposed to, right?  A mechanic friend suggested it
> may be  a "trapped" air bubble.  But if it is pumping like normal, 
> why
> isn't it compressing the air in the tubes like it is supposed to?  Am
> I missing something, or doing something wrong?  Or is it simply a
> matter of the master cylinder not being in as good a shape as I at
> first thought?  And if the verdict is for the latter, is it that big
> of a deal to rebuild it, since I've never done a dual one before?
> Inquiring minds want to know.  Any and all thoughts and ideas
> appreciated.  Thanks a million in advance.
>
>
> Randy (Cap'n) Hook
>
> Hopewell, PA
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