A  tilting vehicle  cant work properly  unless it has correct suspension action.

A  motorcycle  has correct suspension  movement.  In  a  motorcycle the wheel
always moves in the plane of its inclination.  This  system can be called "in the
plane  suspension" .

Many  people  fit  laterally running parallel  wishbones to tilting vehicles because
they have observed this style on racing  cars  but this can result in a less than ideal
suspension  when applied to a tilting vehicle.

TvA  has experimented with all forms of suspension  and has reached clear
conclusions that the parallel wishbone types are flawed.

When parallel wishbones move while inclined  they cause the wheel to move
dramatically out of its inclined plane.

Imagine  a wheel  rolling from a  flat surface then onto an undulation/bump.  There is
a "natural rolling path" that this wheel will follow  and this path is only possible  if the
suspension of the wheel is arranged to move in the inclined plane.

We  have a  simple visual aid  to assist you  so click on the  picture below[1Mb]

Notice  in the 2  examples  the way  the wheel moves  on a different path because in
one example[ parallel wishbones] it is forced  off  the natural rolling path. The N.R.P.  
is the  path on the surface of the bump/hollow  that shows when a cut is made  
through the profile of the  irregular  surface  at the inclined angle of the rolling wheel  
that is passing over it.

IF  the N.R.P.  is not maintained  then the  slip angle of the wheel  will be
instantaneously  loaded  as the wheel is  scrubbed  across the surface sideways.  In
a real  event  the  mass of the vehicle   has inertia that wants to  resist any sideways
displacement  so the  wheel is forced   to scrub sideways across the surface  and so
causes loss of traction and poor feedback  characteristics.

On the other hand  if the suspension is performed  properly  "in the inclined plane"
then this does not occur.  Many  large corporations   who are ignorant  of tilting
vehicle requirements have proposed tilting vehicles  with parallel wishbones  and
many individuals have built  such vehicles [ as has TvA]

There is only one way to do it  and thats the right way.  In this regard the Piaggio
Mp3  has done the correct thing  and no doubt this is why the suspension on this
vehicle works so well.

Like many  things its  easy  to see but its not obvious unless it is pointed
out.                                                                     TvA.