Barry Schwartz wrote:
>
> 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. . . :-)
> *************************************************
> >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.
> ***********************************************
> 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-
I say "weaker" because there are more leaves in the older fixed spring.
I think Triumph reduced the number of leaves until they reached a point
that the swing spring flexed per their desires. This appeared to be
sufficient at the time, but it seems to me that they went a bit too far
as over time those particular springs are prone do develop that
noticeable say whereas the earlier ones do not. Maybe the culprit is
the box where the spring is mounted. Regardless, the problem can be
solved and the function of the rear suspension significantly enhanced
with less body roll and tendency for wheel tuck with the changeover to
the fixed spring and the camber compensator. Leaving the larger front
sway bar adds to the reduction in body roll even over the early cars
that had a smaller sway bar.
> *********************************************
> >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>
> **********************************************
> 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
> **********************************************
Well, that is true to an extent. The greater number of leaves will have
the effect of concentrating the flex points on the part of the spring
where there are fewer leaves. With the swing springs the flex is spread
more or less along the entire length of the spring. I don't know if
that affects the Sag situation but it is a possibility.
> >and therefore when the car has weight continuously applied
> >unevenly (driver only) it will sag long before an equivalent fixed
> >spring model.
> ******************************
> 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.
Increasing the size of the front sway bar was a measure that was
necessitated by the reduction in roll stiffness caused by the
implementation of the swing spring. Keeping the larger sway bar is a
good thing if going back to a fixed spring, but it is not absolutely
necessary, since the early Spits and Heralds had sway bars that look
down right puny compared to the ones on later Spits.
> 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 wonder if the symptom would ever have appeared in the first place if
the spring was fixed and not the swing spring! Just a thought, and
while this whole discussion is based purely on speculation, my
observations seem to tell me that the later swing spring cars with
longer axles are prone to this sag phenomenon while the fixed springs
don't seem to be affected by it. Knowing as I do that the front
suspension is for all practical purposes the same on all these cars, I
wonder if the swing spring isn't actually the cause and all the other
points are just symptoms!
>Regards,
Joe
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