The brake master cylinder was getting soft on my 88 Vanagon and I suspected
it was the original.  I ordered a new one from the Bus Depot and will share
my experience in replacing same.  Removing the instrument cluster is not
difficult and after that you can get to the brake lines and remove the
master cylinder from the booster servo.  (I do have automatic transmission).

To my surprise the new part came with new electrical sensors and new nuts to
fasten with.  Once I got the old one off though, I discovered that the
electrical sensors on the new part had 3 spade lugs - my old one and the
associated connectors were only set for two contacts.  So I just removed the
new ones and screwed in the old ones that appeared to be in good condition.
I guess the new part is also used on other vehicles that have 3 prong
connections - no big deal since I was expecting to reuse the old ones
anyway.

There is a small rubber ring that seals the master cylinder to the brake
booster.  My old one was left on the booster after I pulled the master
cylinder off, be sure to remove this.  There was a new one in place on the
new part.  There was very minor leakage on the face of the brake servo and I
couldn't detect anything inside it. That's about all the details about the
master cylinder

Alas I wish I were ending here... I bled the brakes on the front left first
and upon going over to the other side, didn't spray anything on the bleeder
before I tried to loosen it and torqued it right off !  I probably should
have used a socket to loosen it and avoided that.  Guess I'll need an easy
out to get that sucker out.  I went ahead a carefully bled the rear
cylinders and after that find that I have a very firm pedal.  I'll take it
for a spin tomorrow after I put the dash back together and see how they
are.  Could it be that all the air in the front brake lines was bled out of
the driver's side??  That would be nice.

Well the moral is be real careful in putting the muscle to loosening those
bleeder screws - use a socket not a wrench.

John Graham
88 Westy - Charlotte, NC