Date: Sat, 28 Mar 2009 08:46:12 -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: Re: another brake saga
In-Reply-To: <20090322214126.DD9591E8130@tc2.main.nc.us>
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I can add some additional info to my saga now. (I have the
previously mentioned videos posted
at: http://www.youtube.com/user/emaglott watch the piston on the
right side.)
I hooked up my pressure bleeder and put about 10psi on the
system. The piston stayed out against the shoe. when I open the
bleeder valve, the piston moves back into the cylinder away from the
shoe. Close the bleeder, it moves back out. I was still suspicious
of the boot so I pulled it back, sort of inside out on the
piston. Then the piston stayed out when I opened the bleeder valve
on the cylinder. Then I took off the pressure bleeder and it still
stayed out, even when I opened the bleeder valve. When I put the
boot back in place, it went back to its old habit of pulling back
into the cylinder. So I'm pretty sure it has something to do with
the dust boot (ha ha). I'm gong to take off the cylinder and put my
old one back on (the one that wasn't leaking yet) and see if I get my
nice firm pedal back.
Edward
At 05:39 PM 3/22/2009, Edward Maglott wrote:
>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
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