Arriving late to the thread, sorry.  Scott mentioned the 2 pistons in
the MC.  I was thinking about an excessive piston travel condition in
the rear brakes.  This is common and I agree with the list experts
that this is usually the cause of poor pedal feel.  I'm not sure
which piston in the MC operates the rear circuit, but if there is
excess travel back there, that piston is going to have no resistance
while the other is already squeezing the front rotors.  Could this
somehow cause the thud?

Edward

At 01:15 PM 3/25/2010, neil n wrote:
>On 3/25/10, Don Hanson <dhanson928@gmail.com> wrote:
> >> Mechanic said he felt no air in system, but pedal feels a little
> >> spongy still. Pedal height actually ok. Braking action seems ok. But
>
> >>
> >   What you feel as "a little spongy" could be your lines
> > "flexing".(expanding under the force of your hydraulics)   That is why
> > racecars use SS braided brake hoses, to give a positive feel to the driver
> > when he's 'on the binders'  I doubt a Vanagon would ever have the need for
> > that precise brake feel .
> >
>
>
>
>Thanks Don.
>
>Right. Forgot. Mechanic mentioned flex hose "flexing".
>
>I just made another short video. Engine cold, pushing, you can hear
>thud (barely), booster vacuum dissapates, hard pedal. Start engine,
>pedal drops a little (normal), you can hear thudding more easily in
>last portion.
>
>youtube:
>
>http://www.youtube.com/watch?v=h6TmvkmAj8Q
>
>Read more in archives, but still can't tell if I have a failed or
>failing seal inside MC causing an internal leak.
>
>
>
>Neil.
>
>
>
>--
>Neil Nicholson '81 VanaJetta 2.0 "Jaco"
>
>http://tubaneil.googlepages.com/
>
>http://groups.google.com/group/vanagons-with-vw-inline-4-cylinder-gas-engines