Why Does a 2-Link Rear Suspension Limit Articulation?

First off, we should take a moment to clarify that a GM style, truck trailing arm (the rear suspension used in NASCAR) is not the same design as the 2-link that is commonly used in the air suspension industry.

The 2-link that we are discussing in this video is the design where the front points are typically bolted into the factory leaf spring mounts. It should also be noted that ladder bars are also a type of 2-link that has similar binding issues that are inherent to the design.

This particular 2-link variant is a very common rear suspension on bagged trucks and is well known to have no capacity for articulation (one wheel up and one wheel down). This binding is caused by the links not being able to pivot independently from the axle. Essentially, if you put the axle on the ground and bolted the two links onto the axle, you will have created a large, stiff "U" shaped part that will resist any pivoting where the links meet the axle housing. Whereas, a 3-link or 4-link, which are attached to the axle housing with bushings or heim joints, will allow the links to pivot up and down, not affected by the other links in the system.

As always, there is a lot more to it, but this quick video should help clarify things a bit.

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Видео Why Does a 2-Link Rear Suspension Limit Articulation? канала Pedantic Publishing