It's not quite clear, why such a fuss is made about the coupling rod, a comparatively insignificant detail of the suspension. If I think back to the first stabilizer of the VW-Beetle in the 1950s, it had no coupling rod at all (see picture below). The stabilizer snuggled up to the axle beam and had its ends at the lower supporting arms where it was mounted on using extensive rubbers and clamps.
Of course, the solid mounting of the stabilizer, particularly at the ends, is important. Indeed, with a coupling rod missing on one side, one could very carefully still drive home. There was no lack of stability, there was only no stabilizing effect.
How then, did the coupling rods come about? Looking at some stabilizers, one has the feeling, that they have been added to the suspension almost as an afterthought, because one can form- and place them wherever one wishes (arrow in the picture below). They only have to reach from one wheel-side to the other and in the event of uneven spring compression, be laid out to take up torsion. They can also then, during the final suspension testing, even be slightly altered.
At the same time, one notices just how filigree some stabilizers are. It would appear, that even the slightest forces have an effect. In addition, it would of course, be important that they get the full spring travel, i.e. they should be mounted as close to the ends of the control arms as possible. In the McPherson system there is generally only one and that is difficult to access, particularly in the case of front wheel drive.
This is presumably, why the coupling rods go upwards to the damper. The disadvantage of this, is that it has an effect on the steering. This is why the coupling rod should be fitted with at least one ball-head, this does however, increase the unsprung mass. As you can see, coupling bars like this are anything but well liked. Until it's proved otherwise, we will assume that there is no particular advantage for the linkage of coupling rods on guided suspension components. 05/15