Mythbusters did something on this - there is some truth to driving faster
over wash board.

David Marshall
VW Adventure Driver and
BMW Adventure Rider
 
http://www.hasenwerk.ca

On Sun,
September 27, 2009 10:06, Rocket J Squirrel wrote:
> During
yesterday's exploration of local campgrounds I encountered a couple
> unpaved roads that were heavily washboarded,* some causing such
bad
> juddering that I had to slow down and creep along so the van
would not
> shake itself apart.
> 
> On the return
trip I tried going sufficiently fast (40 mph or so) that the
>
tires and suspension could float a little. The ride was nearly smooth.
> 
> Okay, this has Vanagon content because I don't want to
damage the van with
> that technique. While it felt miles better
in the driver's seat when I was
> going fast, I wonder if I wasn't
putting a lot of stress on the tires or
> suspension.
>

> Thoughts? Or even better, knowledge?
> 
> 
> ====================
> * I recall reading someplace how
cars create washboard in the road due to
> bouncing off some
existing bump and mashing a second bump into the road,
> which
bounces the next car, creating a third, &c., until you got them
> washboards. However, yesterday I came across a device parked on a
side
> road in the forest that appears to have been specifically
designed to
> imprint the corrugations into the road surface. It
consisted of two large
> drums, each about 6' wide and 4' high,
roughly, mounted side-by-side on an
> axle. The circumferential
surface of the two drums had steel corrugations
> spaced about a
foot apart all around the drum. I bet any tyro FBI
> fingerprint
student could match up with the grooves in the road. The
> device
had a trailer tongue that the front so it could be towed behind a
> tractor or something. To make the roads into washboard roads.
> 
> --
> Mike "Rocket J Squirrel"
Elliott
> 84 Westfalia: Mellow Yellow ("The Electrical
Banana")
> 74 Westrailia: (Ladybug Trailer company, San Juan
Capistrano, Calif.)
> Bend, OR
> KG6RCR
>