This article will explain how to install and upgrade the Rear Sway
Bar on a Beretta.  The car pictured in the photo's is a 1988 Car,
other years will be similar.  After 1988 GM switched to an
internal bar vs the external bar, an adapter kit is sold by a
company called Mantapart.  I have been told also you can take
the bracket of earlier cars and modify them to fit but I have not
done this personally.  My guess is that you could notch the plastic
supports at the top to accommodate the internal bar.  Once you
get an external bar and all the hardware this will probably make
more sense.

First a brief explanation of what a sway bar does.  Most cars
have sway bars on the front and rear as does the Beretta.  It's
Purpose is to help reduce body roll and enhance handling.
On all cars if you want to make it handle better you must think
opposites.  By opposite if you wand the front to handle better
you do things to the rear of the car, same goes for the back.
On front drive cars like the Beretta they have a tendency to
understeer.  My increasing the size and thickness of the rear
sway bar you can help reduce understeer and make the car
handling more neutral.

From information I have been able to collect most Beretta's
came standard with a rear sway bar the exception are some
Base cars from the late 90's. Throughout the years and
depending upon the suspension level the thickness of the bar
changed.  On higher performance suspensions they usually had
a thicker solid rear bar, less performance oriented suspensions
usually had thinner hollow bars.

The First Step in the Project is to locate a sway bar from a 1988
Beretta GT.  In 1988 a one year only suspension option available
called Z51.  The Z51 package included several enhanced
suspension parts and was an addition to the GT package
ordered as a option.  For this project you need to find a
wrecking yard near you and  locate a donor car.  The reason
for using a Z51  sway bar is that it was the largest solid type
rear bar offered from the factory.

To locate a Z51 bar there are several ways to tell if the car has
that option.  The easiest way is to look on the RPO option code
sticker located on the spare tire cover in the trunk.  Simplylook
for the "Z51" code.  If that part is missing you can look on the
drivers side door.  If the tire size is listed as 15 inches thenthat
is also another way to tell.  15 inch wheels were part of the
package in '88.  Finally if neither of these are available you'll
have to get down and look at the end of the sway bar. If the
end feels smooth and is "solid"  you have found one.  Other
standard 88's had a hollow type that had a plastic end cap.
(See Figure 1"A" is the hollow Bar, "B" is the solid Z51 Bar)

Visually the two bars look the same as can be seen in Figure2
One thing I did when purchased mine was to get all the bushings
and hardware that attach the bar to the car.  You might be able
to use the parts from the old bar but since this Z51 is thicker I
used the parts from the donor car.  Something else I did was
clean my bar with a wire brush and sprayed it with some
Black Rustoleum to give it a "clean" look and to hide some
surface rust.

The next step is to remove the old sway bar.  There are four
bolts that need to be removed.  Their locations can be seen
in Figure 3,one bolt on the bottom of each shock mount "A"
and two bolts in the center "B".  Pay careful attention and
notice how the center bushings are attached.  For this step it
is NOT NECESSARY to have the car in the air.  I have a
driveway with a steep slope, what I did was back the car in.
I then had enough room to crawl around under the car to get
the bolts.  The project would be made easier by jacking the
car up and putting it on jack stands.  It might help if you
removed the wheels to get under the car easier but again
this is not necessary.  (WHEN WORKING ON A CAR
ALWAYS BLOCK THE WHEELS TO PREVENT THE
CAR FROM ROLLING AND USE JACK STANDS
WHEN WORKING UNDER A CAR-- SAFETY FIRST!!)

When reinstalling the new (used) Z51 sway bar it would be
helpful to have a extra set of hands but I was able to do it by
myself.  slide the bar into position and attach the outer brackets
first.  Have them loose so the bar can be moved around. Next
step is to then put the center holders into position.  Finallyrotate
the bar into position and tighten the bolts down.  The two middle
bar holders are tricky to put together, you might find it helpful if
you have another set of hands to help hold them together.  Make
a final  check to ensure all the bolts are tight,  then goout and
enjoy your improved handling!

Reference Pictures