Michael Sands writes >
>Caterham...
>The original solid rear axle was located fore and aft by two trailing
>links. These were two parallel rods going from in front of the wheel
>arch to the axle. The side to side location of the original axle
>was controlled by an "A" frame where the legs of the A were mounted
>to the frame, one leg each in front of the wheel arch and the top of
>the A mounted to the bottom of the differential housing.
This is the same setup that Lotus used on the Lotus Cortina. It takes care of
axle tramp and side movement. It also lowers the roll center. I happen to
think that it is a very elegant way to locate a live axle, as it does
everything with only three mounting points on the axle. The A-frame replaces
both lower trailing links AND Panhard rod with a single structure, utilizing
three mount points instead of six. Also, the lateral location is completely
symmetrical which it is not with a Panhard rod. Even a Watt's link is not
perfect in this regard.
I was considering adding such an A-frame to the Midget when a Datsun roadster
pilot told me he was thinking of doing it to his car. I eventually went with a
Panhard rod which does not do all the same things, but did the ones I most
desperately needed done.
>deDion suspension...
>Now the trick. The fore and aft location is still the trailing links,
On the tops of the hub carriers on the ends of the deDion tube, right?
>the lateral location is still the A arm,
Mounted to the middle bottom of the deDion tube, right? (If it goes somewhere
else, how does the deDion tube get located laterally?)
>and there is a tube running from the left wheel to the right wheel.
The deDion tube itself.
>Why they kept the A arm is a mystery.
Huh? To keep the deDion tube from moving sideways, right? Otherwise you would
need a Panhard rod or Watt's link or something. Also to keep the deDion tube
from rotating around the upper trailing links. Otherwise you would need lower
trailing links. The coil-overs won't do anything.
>The end result is that this version of suspension is more reliable
Why would the deDion be more reliable? Because the torque of the differential
goes right to the frame and not to the suspension? What about brakes? I would
think the extra U-joints would be a minus on reliability.
>but slower. The added weight is the problem.
Why should the deDion be that much heavier? Sure, you have the deDion tube, but
you don't need that heavy axle tube that the live axle system uses.
I'm not picking on you, Mike, I know YOU didn't design it!
I am still fuzzy on one point. Which suspension does yours have?
Phil Ethier, THE RIGHT LINE, 672 Orleans Street, Saint Paul, MN 55107-2676
h (612) 224-3105 lotus@pnet51.orb.mn.org (infrequent mail checks)
w (612) 298-5324 phile@pwcs.stpaul.gov (lists go here)
"Gee, I love that kind of talk!" - Tim Conway
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