If the rubber lines that connect to the cylinders or calipers are old,
expansion can lead to loss or pressure as well.  You can buy stainless
lines, but not sure you would feel the difference for the cost.
Also, bleed them well, and annually, insure all air is out of all the lines.
Start right rear, left rear, right front, left front.

When the system is 100%, the braking is excellent.  I have an 84 Westy, and
went through all of the below and other tips.  I replaced front calipers,
wheel cylinders, master cylinder, and new lines... all top quality.
My van stops very well.  Note: if the rear shoes are not set right, you will
feel it everywhere.

Ken and Chris have provided excellent advise, which I can say I did
everything they recommended, and my brakes are fantastic.

Good luck!

Jack

-----Original Message-----
From: Vanagon Mailing List [mailto:vanagon@gerry.vanagon.com] On Behalf Of
Chris S
Sent: Friday, June 15, 2018 10:35 AM
To: vanagon@GERRY.VANAGON.COM
Subject: Re: upgrading brakes in 83.5

I will +1 what Kenneth said. Fully sorted stock brakes do an admirable job
of stopping my Westy Syncro. Keep in mind that although rear brakes do not
contribute much to overall braking performance, they must be 100% correct
for the full system to work. This means correct brake shoes, free adjusters,
correct brake cylinders.  Incorrectly radiused shoes or cheap rear cylinders
and the master cylinder must provide more volume before the system
pressurizes (Think of taking up extra slack). Some drum brake system use a
residual pressure  valve to counter this.  I encourage you to research rear
brake cylinders for Vanagons. =