As you probably know the early disc brakes worked well for their time but like early HD's the lever always felt hard and needed a good squeeze to be effective. I looked into getting a new if somewhat expensive front master cylinder but after getting some advice from glwrench out in Green Bay I did a little digging through my parts boxes. Should have remembered the 82 master has a 5/8 bore like the suggested new expensive one. LOL I have upgraded the GL1500 master for the addition of a sidecar brake by boring it out to accept an 82 rebuild kit. The only issue there is the feed hole has to be moved as the 82 piston is a different length than the 1500. Haven't put it on yet but it is destined to go on a 78 project I have in the background and should help a lot. Already put the 84 hydraulic clutch in it.