Odd. Now you've got me scratching my head when I should be sleeping.
I imagine any weird booster failure mode that might occur would not
be improved by pumping the pedal so it's got to be in the hydraulics.
Which is to say that it's got to be a leak or trapped air. Is it
possible that a flex hose is trapping air in a weird way? You're
sure it's not leaking out the back of the bias block, under the
rubber cap? Does each caliper clamp down its respective disc when
you apply the brakes?
-Joe
At 3:21 PM +0000 6/2/10, alfa-digest wrote:
Date: Wed, 2 Jun 2010 08:21:15 -0700 (PDT)
From: Brian Shorey <[email protected]>
Subject: [alfa] Strange braking problem
Hey All,
We're having a strange braking problem with our LeMons car that has
me scratching my head. Here's the history and symptoms:
The car is a Verde, however we've removed the ABS and replaced it
with a stock non-ABS Milano system. Ran the car for three races,
the brakes have always worked fine, but felt a little mushy.
Noticed that the fluid in the reservoir had drained out over the
winter, put 2 and 2 together and made the blind (and apparently
wrong) assumption that the MC was bad, so replaced it with a new
one, but didn't test.
Later, observed a leaking rear caliper, so did away with the rear
calipers and replace them with Spider rear calipers.
Bled the system a zillion times, including at every possible
junction coming out of the MC and bias block, we're confident that
there is no air in it, anywhere.
Now, we have decent brakes if we pump the pedal, however if we let
it sit, then press the pedal, it goes to the floor with some, but
very little, resistance.
With the car running and vacuum to the booster, everything is the
same except the pedal feels mushy..
Replaced the MC with a used one I had lying around (we'd already
tossed the original), and the symptoms are the exact same.
There are no hydraulic leaks in the system anywhere, we're quite
confident of that, and we're also confident we've got all the air
out of the system.
Tried vacuum testing the booster, vacuum goes to 0 as soon as we
press the brake pedal (MityVac manual says it should drop about 6").
However, we tried another booster I've got lying around and it did
the same thing.
My question is this - is there anything internal to the booster that
could cause the problems we're observing? Every bit of experience
I've got tells me that if there is no air in the system, and no
leaks, then a sinking pedal is the MC. But we're on MC #3 now, and
one of them was new.
Changing the booster is not fun in these cars, especially with a
cage and seat in there, so we'd rather not go that route unless
we're sure.
Any input or advice will be greatly appreciated.
Thanks,
bs
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