Headset hangers produce brake shudder. You can try and fight it by toeing in your brake pads, but all that really does is lessen your braking power to a point that it won't shudder anymore. What you really need to quiet it is a fork mounted cantilever hanger
Get "CAH60" if you're using road levers, the barrel adjuster will be damn useful
You'll also need new housing and most likely a new inner cable (maybe bar tape?) to get this done.