Rear sway bar / 87 Coupe GT

[EKellock@aol.com]

A couple of years ago I bought and installed a rear sway bar from Addco on my
Coupe GT.  I have been mostly satisfied except for one aspect of it.  There
seems to be a very significant "step" in roll stiffness as cornering forces
increase; almost like an on/off switch.  This sudden, disproportionate
increase in roll stiffness occurs at about 6 or 7 tenths and is usually
sufficient to keep me from venturing further, most of the time.  When I do
push harder, it handles very well, keeps things very level, and adds a touch
of tail happiness which contributes significantly to my happiness.  But right
at that "step" it is very unhappy as it makes a smooth and confident line
through a corner nearly impossible to find/maintain.  It's like trying to
stay on top of a rolling log in the water.

Does anyone out there have an suggestion about what might cause this?  I'm
thinking maybe the end bushings are too soft and are being compressed first
until the bar actually start to flex.  Any other thoughts??

TIA

Ed Kellock
Lansing, IA
87 5KCSTQ
87 CGT 2.3