I failed to clearly describe what I was trying to communicate about how
and why adding a spacer to the top of the coil spring stiffens the
suspension by pre-loading it...and why I feel my van NEEDS this
adjustment to be properly set up.  I am not interested in any goal other
than proper set-up of existing components.

Adding a spacer in effect compresses or shortens the spring...since the
spring & spacer must fit where before only the spring fit...put another
way, the spacer basically lowers the height of the top coil-spring
perch.  This in turn stiffens the spring slightly...although many take
issue with that term...as in may or may not coincide with the term
"spring rate"

At any rate, I went and dug up the manual for setting up the rear
suspension on my motocross bike and scanned several pertinent pages,
which are at the URL below.  They explain (with some authority) what I
was trying to explain, and what pre-load adjustment can do for your
suspension.  (The dampening adjustments do not apply to us.)  On my van,
the stock rebound is too soft...front and rear...and out of balance left
to right; not radically, but enough that proper adjustment will
pleasantly if not significantly improve overall suspension performance.
The trick is not to make it too stiff or too soft, but firm and
responsive and balanced...which takes testing on a vehicle as lopsided
as a loaded syncro westfalia.

One request, please do not go to the site unless you have a genuine
interest as last time I got warned by my ISP about too much traffic
:~0.  And once again the file is way too huge, but i just got the
scanner and have so little time to do/learn so much (ya, right.. .)  How
do I scan something so simple without creating such a huge file?  any
tips appreciated.
steve
http://www.concentric.net/~Sxs/preload.shtml