Zaikesman, I believe I can explain this phenomena, and it is interesting because it relates to the effectiveness of this mod.
You are correct in your visualization in that in a pivoted arm, movement is restricted because of the fixed position of the bearings, and wieght placement will not alter what the bearings allow, but it can, and does, shift the forces on the bearings and the amount, and this affects the direction of the forces and the resistance to force.
picture a straight rod with a pivot in the center and equal wieghts on each end. if you bend the rod at the center so that one side is down and the other is level, the other side will then wnat to come down as well, evan though you haven't changed the weight on each side of the pivot. now picture the same straight rod with a lot of weight on one end. the location of the pivot has to change to make them balance.
now flip this stuff sideways and consider the pull of the cartridge on the pivot of a tonearm. to shift the mass in relation to the pivot will shift the force on the pivot, just as changing the location of the pivot change the balance of the arm. in the case of the lateral force, or the anti skate, it would shift to one side of the bearing.
if you were to remove the arm from the table and hold the arm so it hangs toward the floor, it would not hang straight down if you had more weight on one side than the other.
with the arm on the turntable, there is no force on the bearing until the record spins and pulls the stylas away from the pivot. with a change in wieght distribution, you change the amount of force required to pull the cartridge from one side to the other. the nature of the hifi mod is to increase the lateral mass as to increase the resistance to sideways movement. to add a weight on only one side will still increase resistance in both directions, but will increase it more in one direction than the other.
You are correct in your visualization in that in a pivoted arm, movement is restricted because of the fixed position of the bearings, and wieght placement will not alter what the bearings allow, but it can, and does, shift the forces on the bearings and the amount, and this affects the direction of the forces and the resistance to force.
picture a straight rod with a pivot in the center and equal wieghts on each end. if you bend the rod at the center so that one side is down and the other is level, the other side will then wnat to come down as well, evan though you haven't changed the weight on each side of the pivot. now picture the same straight rod with a lot of weight on one end. the location of the pivot has to change to make them balance.
now flip this stuff sideways and consider the pull of the cartridge on the pivot of a tonearm. to shift the mass in relation to the pivot will shift the force on the pivot, just as changing the location of the pivot change the balance of the arm. in the case of the lateral force, or the anti skate, it would shift to one side of the bearing.
if you were to remove the arm from the table and hold the arm so it hangs toward the floor, it would not hang straight down if you had more weight on one side than the other.
with the arm on the turntable, there is no force on the bearing until the record spins and pulls the stylas away from the pivot. with a change in wieght distribution, you change the amount of force required to pull the cartridge from one side to the other. the nature of the hifi mod is to increase the lateral mass as to increase the resistance to sideways movement. to add a weight on only one side will still increase resistance in both directions, but will increase it more in one direction than the other.