Date:         Sun, 4 Jul 1999 14:06:00 -0700
Reply-To:     "Tom L. Neal" <jneal@NETCOM.COM>
Sender:       Vanagon Mailing List <vanagon@gerry.vanagon.com>
From:         "Tom L. Neal" <jneal@NETCOM.COM>
Subject:      Re: '89 Vanagon 10 years of Curiosities and Observations-Bucking
Comments: To: Michael Lichtenberger <mlichtenberger@HOTMAIL.COM>
In-Reply-To:  <19990701093000.34519.qmail@hotmail.com>
Content-Type: TEXT/PLAIN; charset=US-ASCII

> 1) She seems to have the bucking at low speed which is common in these
> vehicles. I have the little dealer capacitor patch but it never fully cured
> the problem. I have also done the Debbie cleaning fix and replaced the
> little switch under the throttle body. Is there anything else to do or
> should I just live with it for another 10+ years?

Not claiming a cause-effect relationship, but mine bucked badly in
gear at idle speeds until a few weeks ago. Now the effect is considerably
reduced, but not completely eliminated. Possibly relevant changes:
 - changed from MXL to MXT tires (connection not likely),
 - put on new Boge shocks (connection very likely, if there is one)

A theory:
The bucking is a driven oscillation from mechanical thrust "noise" that
seems to be related to looseness in the drive train.  This noise appears
is greatest at idle in gear and drives a forward-back oscillation with the
energy stored in the springs.  Shocks dampen the oscillation by absorbing
the "noise" energy.

The above is the simple theory.  The more complex model is a feedback
system with the bucking affecting the drive train further driving the
instability. But the simple theory may be good enough to understand the
problem.

On syncros changing shocks is an expensive proposition:
  $300+ in shocks from  Ken Wilfy or TBD,
  $0 to put on rears myself
  $150 to have someone with a spring compressor spend 3 hours to put on the
   fronts

Cheers, Tom Neal '87 syncro