trailing arms: Goodmark vs. ECE vs. OEM

[SCOTI]

Originally Posted by special-K

The rear suspension is articulated through the bushed mounts. I have no experience with tubular trailing arms, so I have to ask how drastically do they affect the suspension? What are the negative results?

Hey Aus69, I wondered if something like that was possible?

Yes, but that's in addition to the 'bars' design.

The following excerpt is copied from the SA Design book on "Muscle Car Handling Upgrades: Rear Suspension Systems":

Truck-Arm Suspensions

The truck-arm design is another suspension that was never used by OEMs under any muscle car. It was used on many pickup trucks and Suburbans, from 1960 to 1972, hence the name “truck arm.” I mention this system because it has developed a small following in the ProTouring/G Machine segment in recent years.
First adapted for use on racing cars by NASCAR legend Junior Johnson in the mid 1960s, it’s still used on every NASCAR Cup car today. The package consists of two very long arms with an I-beam cross section, rigidly attached to the axle with U-bolts and converging in plane view so they’re very close together at the frame mounting point. These arms are quite rigid longitudinally, but fairly flexible in torsion. This is no mistake! In order for the rear axle to articulate, the arms need to twist. This system is in bind whenever it moves, but the geometry and configuration of the arms makes this binding fairly linear. Mounting pads for a pair of coil springs sit on top of the arms just forward of the axle, and lateral axle restraint is almost always handled with a Panhard bar, although a Watts link would also work. Since this suspension is most often used on circle track cars that only turn left, the Panhard bar (usually called a track bar in NASCAR circles) can be used to induce jacking and tune the car’s behavior. This is perhaps the only application where a Panhard bar may be a better choice than a Watts link.

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So, using a spherical joint in place of the front rubber bushing allows articulation w/o the instant bind . That being said, spherical joints only articulate so far before reaching their limits as well but that would be extreme articulation (think 4x4 trail climb territory). The factory arms flex is still better for the system in over-all function as designed but structurally stiffer square/round tube works & is more consistent within the range of motion allowed by a front joint that articulates.