It is a pretty straight forward mechanism that causes it and mounting the stop on the fork is really the easiest way to reduce it. Pretty much all mountain bikes by the mid 1990s were using these. They were integrated into the stanchion bridge of the cantilever suspension forks and the bolt on stops are everywhere in the mid-1990s. They still make them and you can still buy them. They are dirt cheep and brilliant. I brought a whole schwack of the them into the shop a couple years ago as cross bikes were/are all the rage for commuting and do it all. And of course they all have cantilevers and suffer from bad brake shudder. I would have customers coming back all the time complaining. I would show them the $9 part and mention they would need some extra cabling and a minimal labour charge and their woes would be over. Of course some forks don't have a hole in the crown are shaped funny. IN that case customers are SOL.