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Another benefit of the interconnected bar is apparent when taking a curve at speed. The lean or roll is kept at a minimum due to the fact that force is being applied to the bar from both ends at the same time effectively shortening the bar by one half and curtailing excessive body lean.

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Yup. I do not think it was the T-L per se, but rather the large back seat length in the 127" wheel base Packards. The 122" wheelbase Packards probably had their fair share too. Whatever that might have been, back in the day.

See my edited post.

Gerd:

I found the ride comparison. It is in Packard "Gold Portfolio 1946-1958". ISBN 1870642198 pg 92.

Click on it for a bigger picture:



The top picture is the 1955 T-L. The bottom picture is the 1954 coil & leaf spring.

There is no comparison.

Craig

The tricky point of torsion level, or any interconnected suspension is this: get the car to translate vertically when hitting a bump rather than rotate about its center of gravity.

With interconnection the car is effectively suspended at its CG --Schwerpunkt. Thus an individual bump encountered by either the front or rear wheel will cause the car to rise vertically rather than rotate about its CG first to the rear then to the front as the front then rear wheel rides over it. The moment of inertia of the car in vertical translation is much greater than its moment of inertia in rotation so the effect of the bump is much less.

You can see that in the picture Craig just posted. The TL car actually rotates about its CG (usually known as "pitch") much less than the older car. There is actually a really good explanation of all this in the Packard Film "The Safe Road Ahead".

To go I submit the pic's below. Forerunner of the T/L, or just a bar$tardi$ed cousin?

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Cantilevered springs are nothing new and have nothing to do with a torsion bar type suspension. Here's a Rolls Royce with the same type of setup:

Ross posted:
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Interesting engineering explanation, which I,and maybe others, appreciate you posting.

On the practical side, there are stories about taking reporters over ugly railroad track crossings at high speed during the day -- with the Packard "magic carpeting" over them with no problem.

For my part, and there may be others here who have actually driven their T-L Packards that hard, there is NO QUESTION, that the T-L Packard was vastly superior to anything else extant as far as rough road holding is concerned. But, these days, I usually don't challenge it. The smooth ride over poorly maintained roads is enough.

Craig

Mal: The engine powering that Summit was built in my home town of Williamsport, Penna.

John S.

Others have provided good explanations of the "T-L Effect", and since I'm no rocket scientist, I won't waste time repeating what's already been stated.

However, if one picture is worth a thousand words, how many is film footage worth?

Review the Packard's 1956 promotional film, "The Safe Road Ahead", and I believe that you'll find an animated sequence that shows the action of the wheels and tires of the interconnected torsion bar system over a bumpy road. Then, some live-action footage, shot at the factory Proving Grounds, shows a T-L being driven, at speed, over railroad ties (like a set of train tracks, but without the rails), where the tires are literally tap-dancing against the "road", but that car doesn't pitch about like others with conventional suspension.

Yet, I've seen T-L cars in that and other factory footage, where the front-end of the car seems to float about, eerily, while driving around the concrete track, at speed. I can't explain that action (not even sure that I ever experienced that in any of my cars), but perhaps it is another point in favor of gas-charged shocks.

Now, for a real-world view, you must see the private footage supplied by Bill Allison in the DVD produced by Motor City Packards, showing his cyclecar and a T-L Packard, compared to other brands with conventional suspension, as they traverse some of the worst streets in old Detroit - at unthinkable speeds. (I'm surprised the bumpers didn't get ripped from the other brand cars during that little demonstration.)

I believe the footage that Allison supplied for that DVD also shows some American Motors car fitted with similar suspension, as part of later development work with Ford.