Joe, you basically agree with me, but are saying it in a round about way-
I won't belabor the point any longer, except to add. . . :-)
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>The Swing Spring is weaker than its predecessor (the fixed spring) and
>because of this, and the fact that it flops from side to side, it IS the
>major cause of most sags in late Spits.
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That's exactly my point, (although the spring isn't any *weaker* per say,
it still has to hold up the back of the car, which weighs the same, or on
later models, slightly more. It's just not fixed "solidly" to the
differential in swing spring models. As you say, it ALLOWS the car to
"flop from side to side" agreeing that it doesn't do much to level the
vehicle) but the spring is NOT what's causing the lean, it's ALLOWING
whatever IS causing the list to happen, whereas the old fixed spring would
tend to COUNTERACT whatever is causing the list to begin with-It's kinda
like treating the symptom, not the cause-
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>It's my opinion, based entirely upon comparison of the two types of
>suspension that the swing spring is indeed the cause. It has fewer
>leaves <snip>
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but thicker leaves. The number of leaves is more or less a manufacturing
issue. It matters not so much whether you have 1 or 10 leaves, it's the
total spring rate. Some corvettes have one thickness (leaf) fiberglass
transverse spring. I think you'll find spring rates in the vertical plane
roughly the same, it still has to hold up the back of the car, but now it
doesn't do very much to keep it on a level plane
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>and therefore when the car has weight continuously applied
>unevenly (driver only) it will sag long before an equivalent fixed
>spring model.
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I'm not saying that it's NEVER the main leaf in the rear, but just POSSIBLY
we should be looking at the anti roll bar (which is THE reason it was
increased in diameter, remember the rear spring is now contributing VERY
LITTLE to roll stiffness), or the front springs, of which all three items
just mentioned are doing the MAJORITY of the work of leveling the vehicle.
These may have sagged/changed and possibly that's where you should look
first. As I mentioned before, if you were to remove the front springs and
the anti roll bar, the ONLY thing keeping the car level in the longitudinal
axis, is the main leaf, which by comparison is very weak.- many times
changing the rear spring does not help or helps very little. Sometimes it
does, but again, it may be that the new main leaf is sufficiently stiff,
for a short while, to counter whatever force is causing the list in the
first place. That is until it becomes weakened from constantly trying to
counter that force, and since it is a much weaker spring doing whatever it
can to level the rear of the vehicle, succumbs that much faster. Which
may just explain why it *goes bad* so much more quickly. . .because if you
treat the symptom, the cause is still there -
So possibly a better "fix" for a listing not a sagging (that's another
problem) vehicle, would be to place a shim, similar to the one the GT6 uses
under the DRIVER's side front spring -
I've made my point, probably more than most of you car to read so I won't
drag this one out like some other threads - It was just one of those
observations that came to me whilst thinking of several things suspension
related-
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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