Front Brake Problem

[bwringer]

Worn pin mount holes in the brackets are a common problem. They allow the caliper to tilt and jam slightly - a giveaway is the slanted wear on the pads. If you haven't replaced the mount brackets, examine them closely for wear in the holes. As a guide, the amount of permissible clearance is only enough to allow the slightest of wobble - they can't be too tight, or it becomes problematical the other way, but since we're talking about 30+ year old brackets here you're unlikely to find any as-new ones, but you can find some very good, low mileage ones that will do fine.
As the miles totted up on mine, I became plagued with caliper sticking problems and it took a bit of sorting out. Mine are fine now, but I see no end to the inherent design flaw causing the same problem to recur eventually.
When they're sorted out properly with modern pad material, these are actually half-decent brakes, but it takes very little neglect or wear to let them backslide into being horrible brakes of the 80s.

Agreed on all points. At around 110,000 miles I installed brackets and pins from a much lower-mileage bike and it helped quite a bit. In my case, they weren't binding, but they were actually rattling a good bit over bumps.

They're still a looser fit than needed, so you end up with angled pad wear and rattling calipers. I think if you have a good machine shop around, you could also have the brackets drilled and sleeved for a nice not-so-sloppy fit.

As Grimly stated, GS brakes work much better than you'd think when they're sorted out.

 

[Lorenzo]

You said you replaced everything, with new parts, from master cylinder to caliper;

that includes the brake lines? I had the same problem on the RG, with one line swelling under braking;

you also said, you bled the system in any conceivable way, even pneumatically;

have you tried vacuum bleeding it?

I have done it with off the shelf tools, and it came out quite tight and firm.

 

[silverhorse47]

Is the rotor worn equally from the centre, or worn more on one side only?

S.