Front lower control arm inner bushing failure

["ksgrimsr <knut.s.grimsrud@xxxx>" <knut.s.grimsrud@xxxx>]

The front right lower control arm inner bushing failed on my daily 
driver yesterday, and I have a couple questions about the setup.

Let me first describe the nature of the failure -- the inner sleeve 
of the bushing separated from the vulcanized rubber of the bushing 
body resulting in the inner portion of the control arm shifting 
across the captured inner bushing sleeve under stress. The resulting 
change in front suspension geometry causes alignment to be lost and 
can be disconcerting if there is such motion at high-speed.

While replacement is straightforward (although tedious), and I have 
had the springs out of the car several times before, I was a bit 
puzzled at the setup. With the lower inner control arm bolt torqued 
to spec, the inner sleeve of the bushing appears to be pinched and 
frozen in place between the frame members it's bolted to. With the 
outser sleeve of the bushing pressed into the lower control arm, and 
the inner sleeve of the bushing pinched in place, it would appear 
that the suspension travel would invariably twist the bushing in a 
way that would result in the bushing rubber twisting loose from the 
inner sleeve, like the failure on my car.

How is the lower control arm geometry and bushing setup supposed to 
work? Is the intent that the vulcanized rubber of the bushing be 
pliable enough to accommodate the repeated travel of the suspension? 
If that is the intent, then any bushing replacement that uses harder 
materials for that portion of the suspension would seem to be 
unusable, since the bushing body itself is responsible for 
accommodating the twist associated with the full travel of the 
suspension.

Since pulling the lower control arms out is not my favorite DeLorean 
job (I always get nervous about compressing the springs), I'd like to 
do the job right. Unfortunately, the original setup doesn't look at 
all to be robust and I'd hate to do all the work to replace the 
bushings just to have the fix be short-lived.

Knut