To improve my brakes, I have installed Audi G60 brake calipers and vented rotors on the front and vented disc brakes on the back but I thought that I could improve the brake system even more by installing a bigger brake booster.
After scrounging through a lot of wrecking yards and looking at brake boosters I found a 10" booster that will fit the Vanagon without any major modifications.
The original Vanagon brake booster has a 9" diameter so an upgrade to a 10" means that it is like putting about 20 percent more force on the pedal with the same effort.
The brake booster came from a E30 (3) series BMW, which is easy to find in wrecking yards, made from 1982---- 1990, and until 1993 for the convertible.
To make it fit, a 1/4" piece has to be cut off the threaded rod, then the original clevis from a Vanagon has to be drilled out and tapped to M10x1.5 (drill with a 11/32" drill) and mounted onto the threaded rod.
Adjust the length of the rod to 111,5 MM or 4 3/8" from booster mounting face to the center of the clevis. (see Bentley page 46.10)
I took the instrument panel out, removed the master brake cylinder, unbolted the aluminum pedal frame and took the booster out.
While I was in there I also took the clutch pedal out and checked and lubricated the pin.
In order to get the clutch pedal out, the main pin has to be partially slid out, just enough to get the clutch pedal out.
Check and see if the hole in the pedal is not wore out and that the pin is in good shape.
Here is a link that describes it: