you can replace the booster without moving the dash.
I would even say DO NOT remvoe the dash to replace the booster.
they way you do the boooster is a bit odd........but it comes out, after
removing the insturment cluster, then the master cylinder, then unbolting
the pedal assembly, and lifting it up enough that you can unbolt the booster
from it.  Whew.

you know 'the test' for a booster, right ?
here's how you do that :   With engine off, apply the brake a number of
times, until you've used up the vaccum in the booster.
then , holding down the brake pedal, start the engine.
the pedal should suck down an inch or two when the engine starts.   if it
does......merans the booster is working.

I also consider them somewhat 'nebulous' in not so black/white about whether
they are really OK or not.
 Sure would be nice to have a brand new on on hand to try.
fwiw ..........I saw a case where someone with a only 4 or 5 year old Honda
Civic had both the MC and booster replaced by a Honda dealer - to the tune
of  $ 800 or so.  I know a Honda brake booster is not likely to fail in that
time.  I called that Honda dealer and talked to them - they said .........if
any brake fluid gets into the booster, you have to replace it.
  In a world with unlimited funds to invest on our Syncro's ..........that
would indeed be nice  - to replace the booster if any doubt.
I also don't see how they can really work as long and as well as they seem
to.
  I'll  say this - if there are a lot of miles and years on it, and you can
afford a good quality new booster........I don't think that would be a waste
of money.
  scott
www.turbovans.com
----- Original Message -----
From: "Kim Brennan" <kimbrennan@MAC.COM>
To: <vanagon@GERRY.VANAGON.COM>
Sent: Saturday, July 26, 2008 5:20 PM
Subject: Soggy brake pedal

> Okay, I've bled the brakes. My Westy Syncro still has a soggy brake
> pedal. If I pump, it gets a little better, but not much. Sometimes I
> hear a buzz, and it gets to be the best. If the engine is off, it
> feels better, but with the engine running, it feels really mushy. A
> friend suggested the brake booster might have a vacuum leak.
>
> Don't believe I've seen this come up before. Master cylinder, yes, but
> not the brake booster. I haven't yet looked in the bentley to see
> what's involved. Half afraid the dash will have to come out.