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The
Story:
The Thunderbirds
front suspension can be tricky to work with. This set-up that I
finally decided on. It took a year on and off to design. The current
set-up is actually the second generation. The problem with the Thunderbirds
front suspension is the lower control arm. It is only stable when
the strut or a similar device is used because it has only one mounting
location at the main front crossmember. Without the strut in place
the lower arm will twist when the weight of the car is put on it.
Do not try to just put a set of 255C's in the front, without some
serious fabrication to stabalize that lower arm. It will twist and
rip the bag. I know, because I did it! The Air Ride Technologies
"Shockwave" has worked the best for the front bag set-up
so far. There are most likely other methods, but for a bolt-on systems
with no cutting of the car, this is, in my opinion, the best. Most
of the Thunderbirds on this page will use this front system, but
air cylinders are also another option and are less expensive. There
are mixed feelings about them as far as long term reliablity and
ride quailty for a daily driver. Hopefully this page will inform
you and allow you to decide which system will work best for your
application.
The rear suspension
is easy to do as far as the fabrication goes. The rear is similar
to the front of a full size Chevy truck. It is simply a lower control
arm with a spring pocket and an upper control arm. In order to install
the rear bags the rear bumpstop has to be partially removed. This
will allow the upper and lower cups to seat properly. The weight
of the car holds the assemby in, just like the coil spring was.
Theoretically
you could put the strut and the rear coil back in the car if you
needed to remove the air system for some reason.
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| This is the lower part of the
front bracket tacked together for fitting. It will be fully welded
later. |
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The completed front upper bracket. All the steel
is 1/4" thick. The gussett keeps the upper plate from bending
with the weight of the front end directly in the center of the upper
plate. My opinion, YES the gussett is necessary!
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The left picture shows a little piece I made to
keep the shock part of the "Shockwave" from spinning on
the bag and putting pressure on the shock adjustment knob. The right
picture is the bent piece welded in place
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Fully welded front lower bracket. The
3 bolts replace 3 of the original "Shockwave"
bolts to keep the lower bracket from sliding
off the "Shockwave" when the weight is
taken of the wheel. The lower part of the bracket is what makes
the system work, it acts like the stock strut did and wont allow
any twisting of the lower control arm. All the front weight is on
the factory locations and then transfered directly into the bag
end caps.
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This is the installed unit. The air line can be
run in any configuration that works best for you and your line size.
This picture is actually before I upgraded to 3/8" line. In
the right picture you can see the factory hardware is used to mount
"Shockwave" to the lower control arm. Also this particular
lower bracket design allows you to change the shock adjustment easily,
by reaching behind the front wheel to turn the knob. It is recommended
1 click for every 10 PSI used at ride height.
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This is inside the passenger side fender. The
red arrow points to the hole that was drilled and groumeted for
the 3/8" air line.Behind the hole is the kickpanel area. Note
the split loom on the air line as it passes through the fender at
the top.
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This is what I call the "Key" which
helps keep the lower cup positioned in the lower control arm. From
a full drop to a lift there can be a "clunk" noise of
the cup shifting in the spring pocket. This "Key" fits
into an existing slot in the lower contol arm and holds the cup
in a more neutral postion.
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This is really the only cutting required for the
air bag installation. Removing the bumpstop makes a place for the
upper and lower cups to sit and be supported laterally. Leave about
1" of the upper bumpstop inplace to hold the upper cup laterally.
The cups just sit in place like the original coil use to. You can
weld the top in if you want to, but its not necessary. There is
really no access to weld the lower cups in place. This '89 control
arm is different than the '94 for example. The newer arms are cast,
but require the same process. For the models later than '89 shorter
shocks will be needed. The stock shock will hold it about 2"
off the ground fully dropped.
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This is the difference in the height of the lower
cups needed to lay the rear on a 16" wheel (taller cup) and
an 18" wheel (shorter cup).
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The completed rear bag installation. My set-up
uses a Firestone 224C. I recommend using the 255C which is a smaller
diameter bag. The red arrow points to a close spot where I had to
trim so the bag wouldn't rub them. Also, pay attention to the front
of the bag near the upper control arm, make sure you have clearance.
My bag is also offset because of the size. The 255C can really be
mounted centered on the cups without a problem.
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This is the inside of the rear upper cup. That
is a Weatherhead DOT 45 degree, swivel fitting for the 3/8"
air line.
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THIS
IS ONLY A GUIDE AS TO WHAT I HAVE DONE TO MY THUNDERBIRD AND IS
BY NO MEANS INTENDED TO BE A COMPLETE GUIDE TO THE INSTALLATION
OF AIR SUSPENSION ON ALL YEARS OF THUNDERBIRDS. IT IS EACH PERSONS'
RESPONSIBILITY TO RESEARCH AND INSTALL THE COMPONENTS CORRECTLY
AND SAFELY!! TAKE YOUR TIME!!
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