I don't think you understand how the front wheel hubs on our cars work. The entire wheel hub assembly bolts onto the front spindle, and the bearings are contained within the wheel hub assembly.
There are no bearings inside of the axle! These aren't front-wheel drive cars, after all. Here is a diagram from the Service Manual:
As you can see, the bearings are contained within the wheel hub assembly. The entire assembly bolts on to the steering knuckle and stays stationary against it; the only moving part is the wheel hub itself, via the bearings contained within. Now, the brake caliper bracket mounts up to these two holes:
As you can see, the calipers also stay fixed in position. The wheel hubs have some flex. In fact, the Service Manual even has a spec for how much flex is acceptable:
Definition of Axial end play: "Most ball bearings are assembled in such a way that a slight amount of looseness exists between balls and raceways. This looseness is referred to as radial play and axial play. Specifically, radial play is the maximum distance that one bearing ring can be displaced with respect to the other, in a direction perpendicular to the bearing axis, when the bearing is in an unmounted state. Axial play, or end play, is the maximum relative displacement between the two rings of an unmounted ball bearing in the direction parallel to the bearing axis. Since radial play and axial play are both consequences of the internal geometry of the components in a ball bearing, they bear a mutual dependence." Source:
nhbb :: hitech engineering :: radial play
So what happens when they flex is that the rotors (which are bolted up against the wheel hub via the lug bolts) can push up against the pads and push the pistons in slightly, resulting in more pedal travel the next time you step on the brakes. This is a basic and well known phenomenon that is common to all fixed-caliper systems. I really don't understand why you can't get your head around this. It is so elementary. Truth be told, I'm beginning to think that maybe you don't
want to get your head around this, and that for whatever reason you've decided that you want to be argumentative.
StopTech has made available a technical paper explaining what causes pad knockback better than I ever could, yet you refuse to accept it because you think it's a marketing gimmick, which makes absolutely no sense because standard braking systems on passenger cars use floating calipers and don't have pad knockback. In other words, it makes no sense for StopTech to supply this write-up as a marketing tool because if anything, it would give people reason to not upgrade from a floating-caliper system to a fixed-caliper system (which all of theirs are). This paper would do more to hurt their sales than help them!
But let's see if we can approach this from a different angle. Maybe you and I are going around in circles because I don't understand exactly what it is that you're trying to argue. So, what exactly is the position you're trying to take on all this? That pad knockback is a myth and doesn't happen? Or that it happens, but it's not caused by wheel hub flex?