Date:         Thu, 6 Sep 2007 11:32:22 +1200
Reply-To:     Andrew Grebneff <andrew.grebneff@STONEBOW.OTAGO.AC.NZ>
Sender:       Vanagon Mailing List <vanagon@gerry.vanagon.com>
From:         Andrew Grebneff <andrew.grebneff@STONEBOW.OTAGO.AC.NZ>
Subject:      Re: Road stabiliy issues or swaying in the wind
In-Reply-To:  <46DED1C1.7090404@telus.net>
Content-type: text/plain; charset=iso-8859-1; format=flowed

>I'll bet savvy westyites put the fluffy stuff up top, including the
>cabinets, and put the dense stuff on bottom

Yes, keep the center of gravity as low as possible. With a camper,
with a heavy poptop and one-sided cabinetry this is not really
feasible empty, but packing correctly can reduce any further
disruption of the vehicle's dynamics. DON'T put anything on the
roof!! Relocate the water tank under the floor center or above the
trans. Of course the noncamperized T3 is known for a low center of
gravity, which is why it can be run hard on a racetrack.

>Another issue is fore/ aft  weight bias, much has been said about our
>vans being in the 50/50.  While this is a contradiction to what I said
>above, the fore /aft weight bias, for stability is better biased to the
>front. So if you can move as much weight forward, stability will
>benefit.  A good demo is to take a shopping cart for a spin.  Try
>loading with bias front and rear and central.   Use milk and such.
>Notice how easy steering is with the bias aft and central, and difficult
>with the bias forward. Stability because of forward weight bias, like
>all car and truck designs  except ours, occurs because the polar moment,
>or spin axis, is forward of  the center of the vehicle!

Front bias is not good in cars (it might be in ships, because a light
stern is easier to swing around by the tiny rudder surfaces there).
In a car this results in understeer, which takes the fun out of
cornering... ask anyone who has an Audi (this is why Audi is
currently moving its engines rearward so that they don't hang out in
front of the front axles). Excessive understeer is less than no
fun... it means that if you're caught-out by a decreasing-radius
bend, you may plow nose-first off the road. Note that it appears that
too much mass hanging out of the rear of a vehicle can also cause
serious understeer... such as with my 84 Caravelle with 3.8 iron V6.
Also any heavy bias will cause the suspension at that end to work
harder than it should, and with cheap dampers (KYB etc) they won't
last as long and may well not be able to cope with bumpy roads; you
don't want a floaty ride at aither end, as such a vehicle won't pass
the Moose Test (same as for crappy tires). What is needed is the best
compromise, and that is with the bias within the wheelbase.

>Lastly is caster adjustment on the front end alignment, more caster,
>equals more stability.  Have it checked or even tweaked by a good
>alignment shop as well as the   camber and toe in.  A good front-end
>tech will be able improve  your setup for optimum stability.

Yes! But remember that increased caster will also increase steering
effort. Adjusting for negative front camber will also help for those
who like fanging it on bends, but too much and you'll wear the inside
edges of the tires.
--
Andrew Grebneff
Dunedin
New Zealand
Fossil preparator
Seashell, Macintosh, VW/Toyota van nut
‚ Opinions stated are mine, not of the University of Otago
"There is water at the bottom of the ocean"  - Talking Heads