Date: Sat, 26 Nov 2011 07:54:40 -0800
Reply-To: Don Hanson <dhanson928@GMAIL.COM>
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: Don Hanson <dhanson928@GMAIL.COM>
Subject: Re: Westy Weighed... Setting Corner Spring Rates
In-Reply-To: <4ed0def9.c2c5e70a.6458.ffffbedb@mx.google.com>
Content-Type: text/plain; charset=ISO-8859-1
On Sat, Nov 26, 2011 at 4:43 AM, Derek Drew <derekdrew@derekmail.com> wrote:
> Nobody seems to really have any sense of what the correct answer is
> to this query.
>
> It is important because this might be one of the most advisable
> practices for Westfalia and 15 years from now all Westys will be set
> this way after everybody wakes up.
>
> Or, what you read below might be utterly bozo engineering.
>
> I have no idea which of these is true.
>
The most important part of setting up a vehicle for optimum handling is
corner weights. The ride height has to be adjusted properly to achieve
optimum corner weight distribution. Until the ride height is properly
adjusted, nothing else will make any predictable and consistent
difference. You could put 300lb springs LF/RR and 1000lb ers RF/LR...and
still not even up the actual tire load if the ride height is not
optimized. Wheel alignment, too, is totally dependent on ride height
adjustment. Suspensions work as a System...changes to one part of the
system affect the rest of the parts of the system...Corner weight and ride
height are very interdependent....You adjust your corner weight by changing
the ride height...and of course standard suspension on a Vanagon is not
very easily adjustable.
Spring rates: First, you must have the load at the tires adjusted to
optimum....that is where you can start calculating the spring rates you
want....Using the body work to measure ride height is not very accurate.
To be accurate, one needs four scales and a very very level spot to set
up. The ride height needs to be measured at some chassis point that is
close to the suspension axis of movement..... As little as 1/16th of an
inch change in ride height can transfer a hundred lbs of tire load from
corner to corner.....A few hundred lbs of tire load makes a huge difference
in how a vehicle will respond in low traction situations. You simply
can't expect to get any meaningful improvement in vehicle behavior by
willy-nilly swapping of springs of different rates, without first getting
it evened up on it's tires....Period.
In the original post, it was mentioned the LR/RF had a hugely bigger load
than the two opposite corners, right? Think of your dining room
table...the one that rocked on it's legs till you stuck that matchbook
under one leg (or more properly cut the longer legs down). Now, think of
those legs ...If you make the two lower corner legs out of 6x6 timbers,
they still would be too short. If you say..."hey, these tall legs, they
are holding up 200lbs of food and drink, I better make them from angle iron
to carry this big load"....they will still be too long and the table will
still rock and spill your wine....
Heavier springs/lighter springs...change the springs very much and you
will need to change the shock action, too. Dampers/Dampeners...whatever,
the shocks control how quickly the springs compress and extend.
Suspension art is really fascinating and quite a study.
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