[VAC] Re: Shocks

["Dr. Gerald N. Johnson, electrical engineer" <geraldj@xxxxxxxx>]

That Airstream shocks work backwards might be true for those mounted
horizontally. Basically the direction of most resistance depends on
which way the check valve in the piston is turned, IF there is a check
valve. Its totally practical to make a fixed orifice for a simpler
shock, but the trouble is that sucking tends to cause cavitation and to
get gas mixed in with the oil that kills off the performance. Even then
the compression force would be higher than the extension force because
the compression side of the piston has a larger area than the extension
side (because of the piston rod). One could also fill the shock exactly
full so there was no air and if the shaft seal didn't leak (and gas
shocks tend to not leak) you could pull against the oil on the rod side
of the piston. The function of the gas pressure is to reduce cavitation
and bubbles getting into the oil.

Most of the shocks I've replaced (except gas shocks), the new shocks
seemed stiff in both directions. There has to be compromise, too stiff
in the compression direction transfers too much road feel (ride is
harsh), not stiff enough and the spring bounces.

Gerald J.