It's nothing more then properly bleeding brakes. When brakes are bled, all air has to be removed. Sometimes a common bleed at the calipers is not good enough and the system requires more attention.
This was your first post above before you edited it.
Sometimes that means cracking a hose line at the back of a master cylinder, or hose connection, or at the hose going into a caliper. Sometimes that means dismounting a caliper and holding it in a higher position then the master cyliner so the air rises to the caliper for proper bleeding. Proper bleeding means doing what ever it takes to bleed all the air out of the system.
On some systems like ours, and with how our tubing/hoses are routed, it is easy for air to get traped in various places. One of those is at the hose/tube connections near the steering head. Many of these problems are induced by improper bleeding methods such as using speed bleeders or vacume pumps. A system having air will have a low/inconsistant peddle.
SC-Wing posted how a Wing was fixed in posting #238 http://gl1800riders.com/forums/showt...+brake+shutter
. He posted what a Honda mechanic needed to do to get the air out of the system. He cracked a bleeder and found air near the steering head. A short time later, Rocky did the same and proclaimed a fix to a known rear brake sutter problem. Which is probably true for the ones with air trapped in the system. For the rest of us, it is not so true.
For the ones riding on a hot days, with properly maintained braking systems with no trapped air and a rear chatter not caused from air in the system, we've had to learn proper braking is the only fix. Proper braking requires using front and rear brakes simotaniously