Date: Sun, 22 Mar 2009 17:39:18 -0400
Reply-To: Edward Maglott <emaglott@BUNCOMBE.MAIN.NC.US>
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: Edward Maglott <emaglott@BUNCOMBE.MAIN.NC.US>
Subject: another brake saga
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I was having wonderful brakes after replacing my master cylinder a
year or so ago. Apparently I had been driving around with little or
no pressure to my rear brakes for a while. All was well in the brake
department until I started losing fluid. Then I started losing fluid
fast, and had very poor stopping power and a puddle at my right rear wheel.
Rear wheel cylinder failure, drained all the fluid out of that
circuit and I know I pumped air into it. I also think the pedal hit
bottom during this episode. Off to FLAPS for 2 new wheel cylinders
and new shoes. Debated waiting and getting cylinders from BD or
another list vendor, but was in a hurry to work on it while I had
good weather. OMG what a mess on the side that had been
leaking. yuck. Got everything cleaned up and put back properly and
adjusted properly so the shoes were barely touching the drum. Bled
the system with the old fashioned GF pumping the pedal method.
Pedal remains soft. Meanwhile I score a cool pressure bleeder on
Freecycle. So give that a try, didn't get any more air out. (Maybe
a tiny bubble or 2.) I bled out about 12oz total which I think
should be enough. No change in pedal. I review archives and read
about bench bleeding the MC, which I did when I got the new one. I
do this with it in the van. Just cracking the lines and trying to
catch the fluid with rags. No change. I go for a drive on some
gravel roads and find I can't lock the rear wheel with the
brakes. Fronts do lock. On pavement I can't lock any wheel despite
what feels like a LOT of pedal pressure. Can't really tell if I'm
hitting bottom in that situation.
I decided to pull the rear drums to see what is going on in
there. Weird thing. On One of the new cylinders the piston toward
the front of the van pulls back into the cylinder on it's own. I
think it might be the rubber boot pulling it back. It goes slowly
but ends up with a pretty big gap between it and the shoe. Up to
about 10mm if you wiggle things and wait a couple minutes. I looked
at the cylinder on the other side and it seemed to be fine.
Questions: I'm thinking that on the first press of the brake pedal
the rear circuit is going to spend all that fluid to push that piston
out to the point where it touches the shoe and the rear brakes aren't
going to do anything. Yes? How much fluid do I need to drain from
the right rear wheel before I am sure I have bled the whole circuit
from the MC to the wheel. How much for the front? Bentley mentions
pushing a lever on the brake pressure regulator, but there is none on
my '86. I remember other VWs having the kind with the lever, is this
just an error?
Any other ideas appreciated and thanks in advance.
Edward