We are often asked why pushrod systems aren't more common despite their significant advantages. For motorsport, the answer is simple: it depends on whether the regulations permit a pushrod linkage for the shock absorber. Take the racing series sanctioned by the DMSB (German Motorsport Federation):
apart from Group H in slalom and E1 on hill climb races, there's no way to retrofit a pushrod system.

The situation is quite different for production vehicles. Theoretically, manufacturers have free rein. However, besides the cost (pushrod = more parts in the suspension = more expensive), the issue of installation space usually prevents the use of pushrod linkages. A mid-size station wagon without a trunk because internal shock absorbers take up space? Impractical!

This is why pushrods are primarily used in extremely high-priced sports cars. Production costs are negligible, and trunk space isn't needed anyway.

Now we come to our personal ZORN Motorsport ranking regarding the advantages of a push-rod system and why it makes sense to retrofit push-rods:

The basics:
From a physical perspective, the connection between the car body and a wheel is a so-called two-mass oscillator. Mass 1 is the portion of the car body related to a single wheel. This mass is correspondingly much higher than Mass 2, represented by the wheel and its mounting, including all attached components such as the brakes. Because the car body is decoupled from road irregularities by a spring, Mass 1 is referred to as the sprung mass. Mass 2, in contrast, is the unsprung mass; it is directly affected by road irregularities. For stable, controllable handling, both masses must be damped relative to each other – otherwise, Mass 2 would introduce uncontrolled excitations into the body.

The importance of unsprung mass:
It may be hard to believe, but it can be summarized in a single sentence: a lower unsprung mass transmits less energy into the body in terms of vertical dynamics, which benefits the stability of the body and thus the controllability of the handling at the limit.

Admittedly, this is generally not an issue for today's road cars. For reasons of comfort alone, these use relatively low spring rates and long damper strokes. This reliably dissipates the transmitted energy without significantly impacting the body.

The situation is quite different for racing cars: they not only come with high spring rates and low ground clearance, which causes reduced damper strokes. They also typically have a significantly lower body weight, which considerably worsens the ratio between mass 1 (body) and mass 2 (unsprung mass), thus drastically increasing sensitivity to vertical dynamic stimuli.

It is therefore obvious that any reduction in unsprung mass, whether through lightweight rims, weight-optimized brake systems (e.g., ceramic), or a push-rod damping system, benefits the body's stability – with the aim of making handling more controllable at the limit.

Now let's look at the numbers: the extent of savings becomes clear when using a Golf 2 as an example. While a standard coilover strut for the rear axle weighs approximately 4,900g, the pushrod made of high-strength aluminum (with two steel uniball joints) weighs only about 700g. So the reduction is a full 85 percent!

If we consider the savings across the entire suspension (including axle, brakes, wheel, etc.), the overall reduction is approximately 14% (assuming 30kg before / 25.8kg after).