1956 Packard Panther Project

Panther "Restomod" Projects

Front & Rear Sway Bars Subproject

1955-56 Packards Torsion-Level cars had a small single front anti-sway bar. Although this was helpful to control body lean during cornering in its day, modern tires can grip much better which can cause more body lean than the original sway bar can deal with.

I decided to apply more modern anti-sway bars to my Panther.


The first question would be "Why?" I will grant that a T-L Packard probably handled better than any other mid-1950s big car just based on the T-L suspension alone and that's one of the reasons I and many others like them. However, there's always room for improvement. Given that, the question becomes: "how to improve it."

Mid-1970s Firebirds, particularly Trans Ams, were outstanding handling cars. A stock Gen-2 Trans Am was capable of negotiating a skid pad test at around 1.0G, which is beyond what most drivers are capable of utilizing. Since I used to have some of these Firebirds as parts cars in other projects, I figured I would start there. Below is a picture of the front subframe of a 1981 Firebird inverted right before it got sent to the metal scrapper. This shows what the front sway bar looks like and how it is attached.



Front Sway Bar Adaption

The frame rail connections are about the same comparing the T-L Packard to the Firebird, although the distance between mounting points is somewhat different. However, the sway bar end connections are quite different. Of course, I mocked up how the mounting might align just by hanging the Firebird front sway bar onto the Panther chassis with coat hanger wire:



The most difficult part of the adaption will be how to mount the ends to the Panther front lower control arms. This is what I did.

I cut and modified a length of steel "U-channel" from the local Home Depot into a couple of "outriggers" to connect the lower strut from the Firebird sway bar to the Packard lower control arm.



Here's the finished outrigger bolted to the lower control arm with the Firebird end link attached.


One also has to mount the attachment of the sway bar to the front frame rails. I used a pair of 3FT steel "L-channel" from Home Depot as the crossmember. The mounting locations is somewhat different than Packard's T-L front sway bar, but the idea is essentially the same.





Rear Sway Bar Adaption

One might ask: "Why a rear anti-sway bar also, especially since Packard did not use one?" Or one might think that the "S-bar" linkage in the rear of a T-L car is some sort of anti-sway bar too. It is not. It is technically an "inverted Watts linkage" whose sole purpose is to assure the central location of the rear axle under any up/down movement. It has no anti-sway purpose whatsoever. However, the rear trailing arms have some anti-sway effect, but not very much.

As to why a rear anti-sway bar also: This is for handling balance. The stock Packard front anti-sway bar is ⅞" in diameter. The stock Gen-2 Firebird front anti-sway bar is 1" in diameter (the smallest available). This doesn't sound like much difference (⅛"), but because torsional rigidity increases as the FOURTH POWER of the diameter, a 1" torsion bar (anti-sway bar) is 70% more rigid than a ⅞" bar! If I do not install a rear anti-sway bar, Panther will "push" badly in turns because of too stiff anti-sway in the front.

As with the front Gen-2 Firebird anti-sway bar, I mocked it up by hanging with coat hanger wire. I won't show any pictures of that because it's pretty self evident except to say it looked like it would work except that the Firebird strut-to-frame length was 4" too long compared to what I needed for the Panther. So, I had the machine shop shorten (cut and reweld) the struts. Here is a picture of the stock (front) and shorter strut (rear):


Mounting the upper end of the Gen-2 Firebird strut to the existing crossmember was "cake". All I had to do was cut off a little of one end of the bracket, drill corresponding holes in the crossmember and bolt it together.



I used the existing hole in the rear axle tube mount-to-trailing arm as one point. I had to temporarily separate the mount from the trailing arm in order to remove the rubber biscuit and washer and trim same a little bit to make room for the head of the outrigger mounting bolt, as shown:


The outrigger was pretty simple, but it had to be robust. Here's a few pictures showing the sequence of parts and their install:





Here's the entire Gen-2 Firebird rear anti-sway bar mounted with the Packard S-bar and shocks:




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