I've had this problem, was definitely master cylinder.  It failed a little
at first till it went all the way and had to pump the brakes repeatedly to
stop.   100$ get's it fixed, do it yourself, it's very easy.

-Ry
http://www.google.com/profiles/rylincoln

On Tue, Aug 17, 2010 at 3:38 PM, neil n <musomuso@gmail.com> wrote:

> On Tue, Aug 17, 2010 at 12:04 PM, Sheilah Rogers <sheilah@sheilah.org>
> wrote:
>
> > So I was driving in ~80F weather, up and down a not so steep road but
> some curves, about 30 minutes of said road was unpaved, ...... I drove about
> 45minutes total here.
> >
> > Then I got on the highway for another 45 minutes-ish. When I went to slow
> down a bit, it was like my brake peddle wasn't responding with its normal
> sort of push-back and instead, the brake pedal just dropped with no brake
> functionality about 80% to the floor before it engaged. Once engaged, I
> could slow the van down but of course I then had the pedal to the medal just
> to slow down a bit.
> >
> > Being on a quiet highway I kept going, figured I'd pull over in a bigger
> town and at least I can stop the van. But after 30minutes, the brake resumed
> normal so I just continued driving to my mechanic's.
> >
> >
>
>
> Were you driving slower on the unpaved roads? If so, maybe you didn't
> need to push as hard as if slowing down from highway speeds?
>
> Regardless, that sinking feeling usually means the MC is failing or failed.
>
> Any receipts showing if MC was replaced? A time line of how old part
> is may help.
>
>
>
> 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
>