I'm a lurker... I have a 1985 Vanagon GL with brake problems.  Yes I have studied the Bentley quite thoroughly, yes I have tried to get something from the archives, and could not get there numerous times. The one time I did get in, my computer hung up.

   I have checked my brake shoes and pads and they are like new, the rear shoes are tightened as much as possible.  I have checked the one way valve from the intake manifold going to the brake booster, it is right.  I have tight brakes and have good pedal, when I start the engine, the pedal drops and holds just like the Bentley says it should.
I do not have much pedal,  and at times I feel the master cylinder piston bottom out.  I pulled the master cylinder vacuum line, my foot on the brake is constant and solid with no bleed down.  I have driven it with the booster disconnected and I can really romp on it and cause a lockup, it is hard though.. but I do not bottom out.  The Vacuum booster, does not leak, that I can hear, and I even have good brakes to a point, unless I get into an emergency stop situation, the piston bottoms out, it stops in it's own time, with no lock down..?   I have bled the brakes some time ago..?  This may be the point I'm wrong on, since I just thought of it ...?
Marion Lathem
1985 Vanagon GL
Quinlan, TX