[Chrysler300] Front Disc Brake problem solved

["George McKovich" <george@xxxxxxxxxxxx>]

My thanks to all with the helpful suggestions regarding my
power brake (front disc brake conversion) problems on my
1957 Chrysler 300C of several weeks ago. I tried most
everything that was suggested, short of installing the dual
master cylinder. I wanted to avoid doing that, so that it
would not be necessary to remove the MC to enable removal of
the driver side valve cover.

I replaced the calipers, had the rotors turned, replaced the
pads, ensured that no brake lines were pinched or plugged
and even tried a different bellows brake booster. The net
result was always the same.... no additional braking
achieved. I even went so far as to add an electric vacuum
pump to increase the vacuum available to the power brake
system. That pump gave me 21 inches of vacuum but did not
result in additional braking ability. Through all of this,
Roger at AAJ Brakes in Portland was always available with
helpful pointers and encouragement. He even went so far as
to offer me a refund if I couldn't get the brakes to work.
He said he had numerous systems, including his own running
on a single MC, but did recommend the dual for safety. All
through this period, it seemed like I was getting no power
assist from the bellows booster. I then sent the better of
the two boosters I had to Ron Karp in Upland Calif to have
it checked out. Ron tested the unit and said it was working
to about 80% efficiency and that should be good enough to
stop the car very well. I did have him freshen it up with
new O rings and seals so that I could be certain that it was
not my problem. I talked with Ron several times while he
still had the booster and he gave me several suggestions of
things to try..... none of which solved the problem, with
the other booster that I had on the car at that time. While
my refurbished unit was in transit back to me, Ron suggested
I check out the release lever at the top of the brake pedal
arm. When the re-newed booster arrived, I removed the old
one and looked at the lever/trigger mechanism at the top of
the pedal and compared it to two other brake pedal arms that
I had on-hand. I found that the lever/trigger was bent out
quite a bit from the other two. Here is a link to the
pictures: http://imageevent.com/idsnowman/questions  I took
one of the spare units and bench tested it with the re-newed
booster and found that it worked perfectly in the tests. I
then went about replacing the arm with the bent
lever/trigger with one of the spares, installed the re-newed
booster without the electric vacuum pump and now I have
excellent braking ability. The car will stop as well or
better than my 2003 Dodge Ram. The problem all along was
that damned little lever/trigger!! Apparently, that little
lever/trigger was continually pressing against the button on
the back of the booster and not allowing any significant
vacuum boost to the brakes.

Thanks again to all for the help and especially to Jim
Krausman for the encouragement to continue to quest for an
answer.

George
http://imageevent.com/idsnowman/57chrysler300




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