Date:         Thu, 20 Sep 2001 07:11:59 -0400
Reply-To:     Gary Stearns <gstearns@OPTONLINE.NET>
Sender:       Vanagon Mailing List <vanagon@gerry.vanagon.com>
From:         Gary Stearns <gstearns@OPTONLINE.NET>
Subject:      TiiCo vibrations...some progress
Content-type: multipart/alternative;

Seems that most TiiCo owners have found that the engine puts a low frequency
vibration/resonance into the body at about 4000 rpm.  Having experienced
this with many 4 cyl cars in the past, I knew that with careful fiddling, it
can be tuned out.  I had some ideas and decided to give it a go.  I made
several changes at the same time, so my experimental process stinks.  I didn
t figure out which, if any created the biggest improvement. Here's  what I
did:  1) replaced a rusted, thin 3 bolt exhaust flange on the muffler
upstream side. 2) replaced all of the nuts/bolts on these flanges with the
largest stainless replacements that would fit. If the exhaust is
contributing to the vibration, then it's got to be as rigid as possible to
resist. 3) I put rubber spacers (hacked from old muffler hangers) between
the arm that supports the muffler and the muffler itself.  The muffler now
sits on these rubber pieces in an attempt to dampen it's vibrations. 4)
Probably the most effective change: The right motor mount on our Vanagon was
too close to the attachment plate on the engine carrier arm.  I could see by
the shiny spots on the plate that the mount had been "bottoming out" when
the engine twisted under hard acceleration.  I supported the engine, removed
the mount and elongated the holes in the arm attached to the engine.  This
allowed the mount to be pulled away from the plate that it had been hitting.
 Interestingly, from the bottom this arm seems to have been cast in a way
that allows elongation of the holes if needed. 5) Finally, while looking
things over, I pushed on the exhaust header to see how much flexibility
there was. None found in the header, but the engine itself bounced on it's
mounts for many cycles.  Ah... damping needed.  This is wierd but bear with
me.  From road racing experience I have learned that the closed cell foam
found in swimming pool float toys has miraculous properties.  My kids call
these things "noodles".  They can be found at most large toy stores. These
noodles are usually about 3" in diameter, 4 ft. long, wild colors and really
cheap (like $2.00).  I have used this stuff to make suspension bump-stops
for race cars and for our Vanagon.  As long as the foam is contained (as in
the small voids in the TiiCo motor mounts) it has amazing progressive
damping characteristics.  It's also indestructible, it'll be bouncing long
after we're gone. Use a razor to cut pieces that are a snug fit in the motor
mount openings and... quiet!     It's no Rolls, and no one will ever think
that you have a BMW six in there, but it's a huge improvement.

Gary

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