Dan Golder writes >
>On the subject of Spridget suspension designs, one must recall that early
>Sprites ('58-'61) used quarter elliptic rear springs, not semielliptic. The
>change to semis was made with at the request of the American market, which
>wanted a bit softer ride, at the expense of better handling.
Do you have a source for this "American" theory?
I wrote that I don't know who designed the semi-elliptical geometry in the rear
of my Spridget. The quarter-elliptical that preceded it was surely Donald
Healey et al. My guess is that it was MG designers.
The Bugeye or Frogeye was a Healey job. Donald Healey used the
quarter-elliptical spring so he could hang everything on the center section of
the tub. He had been impressed by a Jaguar design that did not stress any of
the rear bodywork.
The brass at BMC wanted a trunk that opened in the back, and wanted to lose the
frog eyes. The front of the design was to be done by Healey and the back of
the car was to be done by MG. The weird part is that they were forbidden by
BMC brass to talk to each other! Fortunately, they did talk to each other on
the sly or who knows what the finished car would have looked like.
The MG designers had a notion of what they wanted to do with the future
replacement for the MGA, but had to do the Midget first. I think they wanted
to put a semi-elliptical-spring Hotchkiss setup in both cars from the jump.
I don't think MG was considering remaking the rear suspension of the Frogeye
for America per se, they were just interested in making it an MG. Whether it
was a cost saving in the retooling, or Healey talked them out of changing, they
retained the quarter-elliptical springs, but clearly left room in the design to
easily change to semi-elliptical springs later. There is a lot of meat that is
not needed in the rear of a quarter-elliptical Spridget.
Meanwhile, the MGB was designed and introduced. It looked a lot like a Midget
from the back, and indeed used the same tail lights.
>Too bad, because there is a noticeable loss of quickness going from a Bugeye
>to a Mark III Sprite (MK II Midget).
Part of that is weight and polar moment changes. The bodywork on the ends is
considerably different. Have you gone from a Mark II Sprite/MK I Midget to a
Mark III Sprite/MK II Midget? They are much more similar cars to each other.
the later one is still heavier, do to the roll-up-window doors.
One of the reasons given when they made the change was to reduce the
roll-oversteer effect. This is consistent with Scott Fisher's explanation of
the design theory of the MGB rear, but the designers did not go nearly as far,
and there is still plenty of roll oversteer in a Midget.
>Second, the brake fluid answer is (as any British car fan knows) that you can
>only use Castrol LMA due to the natural rubber nature of the seals in the
>braking systems of British cars.
Well, there are probably other suitable things about, but the ready
availability of GT-LMA makes you wonder "Why experiment?".
>Silicone is ok as well, but you should rebuild the entire system and start
>fresh if you'd like to use it.
If you ever want to drive hard, stay away from Silicone. It is damned near
impossible to get the tiny air bubbles out. I recommend it for show cars.
Phil Ethier, THE RIGHT LINE, 672 Orleans Street, Saint Paul, MN 55107-2676
h (612) 224-3105 w (612) 298-5324 phile@pwcs.stpaul.gov
It's still hip to be octagonal. Whaddaya call the Lotus emblem shape, anyway?
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