Date:         Thu, 10 Jan 2002 01:55:58 EST
Reply-To:     FrankGRUN@AOL.COM
Sender:       Vanagon Mailing List <vanagon@gerry.vanagon.com>
From:         Frank Grunthaner <FrankGRUN@AOL.COM>
Subject:      On Spring Supplements and Drunken Vanagon Tilts
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Very many years ago (around 1982) when hustling down the Autobahn in our
fresh '82 Diesel Westfalia, loaded with wife, child (2 years old), in laws,
luggage, porta potti, beer, wine and sausage, I remarked (to myself) that the
tail on this beast was low. This fact was readily established by perusing the
rear view mirror and focusing on the bumpers of the cars following. Then, in
a subsequent burst of insight, I realized that the driver's side was lower
than the passenger side. I panicked.

Now, that panic was due to the method of measurement. We were traveling
upward in the parking structure in Venice, Italy. The clearance on either
side of the Vanagon was several microns. Careful driving! The spiral ramp
required that I hold the steering wheel at full lock right turn. This went on
for 7 levels (seemed like 20, but this is a semiquantitative recollection). I
then zipped into a parking crevasse. When I crawled out of the Vanagon, I
noticed a clearance difference from the poptop rear to the top of the parking
structure on the drivers side relative to the passenger side. I then pressed
SWMBO into service as I took the drivers seat and put her mother in the
passenger receptacle. We measured carefully. Then repeated with several
different masses in the various seats. The maximum change in deflection
(right around 1/8 inch) occurred with my contribution in the drivers seat and
my two year old in the passengers seat. I went through all this since I
thought I would never get the camper out of that mousetrap.

We verified these clearances in Rome, Paris and on the ferry to and from
England. The years passed with my grumbling about the front to rear height
bias and the side to side problem. (complaints to the dealer resulted in a
thick coating of Pablum in the form of a reassurance that they were designed
that way). Finally in the summer of 1985, I put the Vanagon in the garage and
began a series of measurements. Tire pressure, axle centerline, tread depth,
frame height, body sill height and van loading. Sand bags substituted for
irritable and impatient humans as well as cargo. When the measurements were
done, I had established that the frame was straight and this piggy had a
rearward weight bias. I then removed the springs, established that left and
right rear springs were the same length. The lab press showed the same load
vs. deflection profile.

I then went to my trusty suspension design text and calculated the preload
difference required to level the car (I was too cheap to get special springs
made and the Westfalia was delivered with the strongest springs in the VW
inventory). Looking at the deflection bumper and upper spring holder, I
became obvious that the donut approach to a spacer would take care of this
problem. There are many less anal discussions of the details by other in the
more recent past in the archives!

Nonetheless, I procured a 4x4 sheet of 1/8 inch thick Plexiglas (PMMA) and
cut 16 spacers with center hole. Sabre saw. Hell of a mess. Deburred and
cleaned the sheets. I then made up spacers in 1/4 inch stacks, placed them
above the spring mount, reassembled everything, put the van on the floor,
rolled it back and forth and then measured front and rear, left and right
frame heights. Plotted the deflection results. Have the data here somewhere
and I put it in the archives early in the age of the middle list. From that
plot, I determined the right size spacer for the left and right rear springs
to make her level. As I recall, I was about 5/8 inch on the drivers side and
1/2 inch on the passenger side. I then treated the Plexiglas segments to an
appropriate whiff of acetone and thereby bonded then into a solid stack. The
individual stacks were then placed in their obvious locations.

Over the years, miles and engine swaps I have often measured the front to
rear and side to side bias. No change to better than 0.5 mm. Now I tuned the
Westfalia to level flight when fully loaded. If the camping gear has been put
in the garage, the tail sits high. If I have her fully loaded, and have the
Honda XL500S motorcycle hanging off the receiver hitch, she sits low.

To summarize:

1. Front to rear bias was there from the factory.
2. Preload resolved height issues.
3. No spring sagging over 19.5 years of use.
4. Involves severe thermal variations: It actually reached 100 F for one or
two days in that period in LA, and our recent cold spell has stressed the
heater by dropping down to 45 F in the bitterly cold evenings.
5. The rumor that you can monitor buttock mass enhancement by following right
to left tilt through adjustment of the rear view mirror is patently false.

Hope this somehow clarifies something.

Frank Grunthaner