I wasn't going to say anything, and I don't wish to start or will not enter
into an on list flaming war, but I must chime in here.
The Swing spring is a very elegant engineering and production solution to a
potentially serious problem with swing axles. I don't think it should be
de-rated because of personal preference. I'll add this is just my opinion.
There is a WHOLE lot more to making a car handle that making a car stiff in
the roll axis. If that were the end all one would simply do away with
suspension all together and bolt the wheels directly to the frame. As with
almost everything in design it's a compromise - Swing axles really DON'T
like a lot of roll stiffness, because this leads to the dreaded tuck under
during spirited cornering in the first place. That is one reason that you
want REDUCED roll stiffness at the rear with a swing spring type suspension
and remember it was made up for in the front by a stiffer front roll bar.
This was done by changing the spring mounting system in the Spitfire,
WITHOUT limiting wheel travel, something that I don't believe can be said
for the camber compensator.
REMEMBER, this is a production vehicle driven on the street by the general
public. While a camber compensator may do the trick, and possibly has it's
place particularly in racing circles, where streetability can and is
compromised on a regular basis for the sake of handling, the Swing spring
was and still is an exceptional solution to a streetable, production
vehicle. It did the job exceptionally well without undue cost - I don't
see anything inherently bad or wrong with that.
The reason that the later MK3 GT6's were converted to the "less desirable"
(not my words) Swing spring was again simply and purely a cost reduction
measure. The Swing spring was *almost* as good as the Rotoflex suspension
at controlling wheel tuck and in handling for a production vehicle, so the
decision was made to fit the cheaper Swing spring which was and I quote
"almost as effective" as the Rotoflex suspension but at a reduced cost. As
a corporate decision concerned with rising costs on a limited production
vehicle there was really no question what was necessary to do -
The only thing I remember in reading the competition manual for the GT6 was
to replace ONLY the spring on the Rotoflex models with the Swing spring,
not the entire suspension. Unless I misread or remember incorrectly which
is a distinct possibility :-).
There is really NO question as to which suspension is superior at
controlling the rear of a Spitfire or GT6. The Rotoflex fully independent
setup with lower control arms is the best of the bunch. . . period.
Kas's solution (the camber compensator) WAS a compromise, not an end all,
just as all other designs are. I'm sure if you asked him he would tell you
that. It just depends upon WHAT you are willing to compromise. I respect
Kas's opinions very much, and don't de-rate the camber compensator at all.
I believe he may have a personal pride, preference etc. in a system he
(helped) develop which is not unreasonable, but at the same time (and this
stems from being a mechanical designer most of my life) I also believe
there may be other solutions that could be just as good possibly even better.
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< original message >
> Now I see where you are coming from. Bear in mind that those documents
were all produced after the introduction of the swing spring
>and after the camber compensator was discontinued. In other words, it was
"the only show in town", so there was nothing to compare
>against. Still, it doesn't explain why anyone, particularly someone in
the Triumph Competition Department) would recommend replacing
>the rotoflex with the swing spring. Apparently the factory was really
proud of the needless investment in R&D that yielded the swing
>spring.
>
>They tackled a problem (Wheel tuck) by reducing one of the superior traits
of the Spitfire, which of course is outstanding roll
>stiffness. Kas' very simple and effective solution didn't take away from
roll stiffness but attacked the problem, not the symptom.
Barry Schwartz (San Diego) bschwart@pacbell.net
72 PI, V6 Spitfire (daily driver)
70 GT6+ (when I don't drive the Spit)
70 Spitfire (long term project)
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