Date: Fri, 17 Sep 2010 17:32:23 -0500
Reply-To: Steve Schwenk <steve@SYNCRO.ORG>
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: Steve Schwenk <steve@SYNCRO.ORG>
Subject: Re: Vanagon Chrome Silicon Coil Springs
Content-Type: text/plain; charset="utf-8"
These will not be progressive wound. They will be straight wound. Progressive wound springs are not a
good trade-off and not what most westy owners want.
There are two was to do progressive springs. The VW factory springs are progressive, but the progressive
rate is obtained by using wire with a decreasing diameter wire at the ends. It is an expensive process
to obtain this result and not at all worth it. (See below.)
The other way to obtain a progressive wind is to vary the wind of the spring. There will be a band of
maybe 3 coils that are wound much closer together than the other coils. This method has inherent flaws
(which is why VW used the more expensive method).
First, injecting a progressive wind into the spring limits the amount of travel it has. Such a spring
will have a taller height fully compressed than a spring wound the other way discussed above. In other
words, the spring has less travel and so will your suspension.
Second, this type of progressive wind has limited use. The vehicle weight is critical. You cannot use
the spring on a wide range of weights as exists with Vanagons, ranging from an empty panel van to a hard-
top Joker camper. What happens is on the heavier vehicles, the progressive coils are compressed by the
additional weight so that they may be bottomed out just under the static weight of the vehicle, meaning
that band of coils turns into a solid band of metal that does not move...it only takes away the range of
travel the spring has. So you wind up without progressive springs and with notably less travel than
stock springs.
Finally, progressive springs are more for the soccer mom than the vanagon enthusiast. VW did not want
people steering away from the vanagon because it had a truck like feel instead of a car like feel on the
test drive. But as most of us have observed, over time, the progressive wind on the stock springs does
not do much. Those last thinner coils end up being compressed all the time. Although they do not rob
travel like the other type of progressive wind, they don't end up doing much for the great majority of
us.
For those reasons, we have junked the concept of progressive springs for the vanagon. They are not worth
the trade-offs in performance and most vanagon people if given the choice based on feel would opt for the
straight wound springs. They provide a more consistent rate of progressing and a more responsive, stable
feel on the road. They will also perform much better across a wider range of vehicles.
As far as the rate, it is a little bit stiffer than stock. The suspension remains responsive, but with
out the side-effects of an under-sprung vehicle, such as kneeling, excess buffeting in the wind, poor
corner tracking, etc. We ran two rounds of prototypes to get the rate where we wanted it and are very
happy with it. With good tires and shocks, they make a vanagon feel just right, like you would expect it
would, not way too soft and wallowy like the stock springs. But not harsh and rigid like the lowered
springs, or some of the others out there. And everything is within stock spec. Ride height will be
about 17 1/4 " on a westy, center of wheel to lower lip of fender. This height is optimal for full
suspension travel (both upward and downward, both being equally important) and for alignment with no need
for dangerous ball-joint extenders.
Steve
Steve
On Fri 17/09/10 2:51 PM , mikes@flatsurface.com (Mike S) sent:
> At 05:09 PM 9/17/2010, Steve Schwenk wrote...
> >Just a heads up for those interested that the
> prototypes for the >Vanagon (and syncro) chrome silicon
> custom>coil springs have been ordered and are in the
> pipeline. This is the >biggest change we have made in the 11
> >years we have been making vanagon and syncro
> springs.
> Will these have stock spring rates or ??? Progressive?
>
>
>
>
