Ok, can anyone clue me in as to what a hydroelastic suspension is?
Since no one else has leaped to the fore, I'll give
it a shot.
The HydroLastic suspension was part of Alec Issigonis'
design of the original Mini, and was a brilliant piece
of work by most standards of measurement. The simple
definition was that it used rubber cones and metal
pins to provide the springing action. One of the advantages
of such a system is that rubber compresses at a progressive
rate, meaning that it got stiffer the farther you squeezed
it. This meant that the cars effectively had soft springing
if you hit a little bump, and firm springing if you had it
rolled over on its doorhandles.
There were two types of HydroLastic suspension, called
wet and dry. The dry kind is the simplest, and is preferred
by Mini racers in general because of its simplicity, light
weight, and familiar feedback. In the dry system, the
suspension is mounted with a parabolic, machined metal pin
that is in constant contact with a truncated rubber cone.
As the suspension compresses, the pin goes farther into
the rubber cone (and because of the curvature of the pin,
it encounters more of the surface of the cone, which also
acts as a progressive spring). There is one such cone/pin
pair at each wheel, all of which are independently suspended
from the floorpan.
Another feature of such a system is that you can adjust the
suspension's stiffness simply by adjusting the ride height,
due to the nature of the rubber cones. This makes the Minis
an ideal vehicle for situations like road rallies, where
they need to skitter lightly across broken surfaces but
they also need to dig in on high-speed sections.
The wet system is a modification of the dry type (and it's
here where the Hydro part comes into play). In the wet systems,
the cones are hollow and filled with hydraulic fluid. There are
tubes connecting the various cones together (I think it was done
diagonally but I can't recall); the idea here was that compression
at one corner caused the hydraulic fluid to increase the ride
height at another corner (and it's the exact algorithm I can't
recall). The effect was to have a vehicle that rode almost flat
on almost any road -- much the way active suspension works today.
The problems with the wet suspension for competition are its
weight -- not much altogether, but significant on a car the size
of a Mini -- and the fact that it gave such odd feedback to
drivers accustomed to body roll and movements. It also didn't
"feel" sporty -- drivers of the early Sixties were used to cars
that rattled and bumped and in general behaved like, well, like
old British sports cars. (Imagine a time when a 1963 MGB was
state of the art... yeah, such as 1935 :-)
I have never had a satisfactory answer about why the HydroLastic
suspension isn't in wider use today. One answer, I suspect, is that
it doesn't provide much in the way of suspension travel, and that
it doesn't work well on heavy cars -- the Austin America, I think,
was the largest vehicle to use it. For the rest, I suspect a healthy
dose of NIH ("not invented here" -- I still find people who presume
this means National Institute of Health) -- that and possibly a
licensing issue.
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