Date:         Fri, 25 Apr 97 23:12:53    
Sender:       Vanagon Mailing List <vanagon@vanagon.com>
From:         mdstockr <mdstockr@neo.lrun.com>
Subject:      RE: Syncro Tire Inflation VS the VC 

I think that you will find that the VC is "engaged" a high percentage of the time.  A wide 
number of factors affect front to rear tire RPM (revolutions per mile) ratio, there-by affecting 
VC engagement:

 1) Tire pressure -- Tire pressure does not change the tire diameter, it changes the 
    tire's spring rate.  A tire's RPM depends in the inflation pressure AND applied 
    load.

    Because of the above, any front-rear weight transfers will affect tire RPM, such as
    during braking and acceleration.

 2) Wheel alignment -- Any tire toe in or out will create tire slip.  The more tire
    slip you have the higher the effective tire RPM.

    Any change in tire camber will affect tire RPM.  If you think of a tire as being a
    cylinder, any camber angle, other than zero, will increase the tire's effective
    diameter and will reduce RPM.

 3) Suspension movement -- Any suspension movement will induce dynamic changes in tire
    toe and camber angle, therefore changing tire RPM constantly.

 4) Steering -- Any steering inputs will change tire toe and camber angles.  This is
    due to change to the front suspension geometry due to steering movement and due to the
    vehicle leaning in a turn.

    Also, while going around a turn each tire travels in a different radius, therefore
    each tire is revolving at a different speed.

So you can see, the VC is constantly engaging and disengaging.

However, tires are an important factor when owning a Syncro.  Make sure that all tires are the 
same size, design and manufacturer.  Also, keep the tire wear even by rotating tires every 6,000 
miles.


--- On Fri, 25 Apr 1997 19:12:56 -0500  Paul Uusitalo <puusital@Adobe.COM> wrote:

>With tire pressures set to VW spec, (take your pick from inside the door
>jam, I run fronts at 40 and  backs at 48) you must be pretty darn close to
>the 3mm F to R tire size difference (Tim describes below) that will cause
>the Syncro's viscous coupling to begin to engage, no?
>

-----------------End of Original Message-----------------

____________________________________________

  Michael Stocker <mdstockr@neo.lrun.com>   
  North Canton, Ohio, USA
  4/25/97 11:12:53 PM EST
____________________________________________