Rear brake issue

[Igofar]

Hold up four fingers in front of you.
Do you see four, or eight?
(Patch Adam’s quote)
Maybe we should stop a
Trying to figure out how the bracket can damage itself (which it can’t )and perhaps wonder if the guide pins, grommets, rotor, grabby brakes etc.
Are causing the assembly to vibrate or wander around causing the marks?

 

[Andrew Shadow]

Valid question.
If none of those conditions are present however, and have never been present, what caused the marks?

 

[Chris09]

It looks like my answer shows up in the swing arm, the bore is no longer round.

Measuring along an axis pointing to about the rear seat - platform intersection, the bore is worn about an extra 8 to 10 thou compared to a measurement taken perpendicular.
About 808 to 810 vs about 800.

Axle diameter measures about 785 all around.

The included angle between the stopper bolt, swing arm bore and major axis of the oval is maybe 80 degrees.

So it looks like there's as much as 25 thou of room for the axle to move if the 80 ft/lb can't lock everything up tight.

At some point it appears that the axle has been shifting within this clearance possibly due to braking, acceleration, swing arm motion and imparting corresponding movement of the bracket relative to the stopper bolt.

 

[Chris09]

Reading a bit further some of the related articles there's a couple things described that I want to double check.
the 15 degree tilt and the not-recommended-by-Honda removal or disconnection of part of the SMC pictured here in.

[question] Is it the upper clevis to fork bolt that Honda recommends not removing, or is it the clevis to pushrod?

[question] Is it the lower SMC to fork bolt or the lower caliper bolt concealed beneath the seal that needs to be removed?

[question] On my center stand; I'd say the centerline of the outer pistons are inclined already about five degrees; once the correct bolt is removed, will it just swing out the needed 15 degrees, or does it come off completely free of the disk to install an appropriate spacer.

[question] Once I've moved it, would there be enough room to inspect the condition of the parts / clean the exposed pistons?

 

[Igofar]

The line on the rear of the SMC needs to be at twelve o’clock if that is easier to understand

 

[Igofar]

Reading a bit further some of the related articles there's a couple things described that I want to double check.
the 15 degree tilt and the not-recommended-by-Honda removal or disconnection of part of the SMC pictured here in.

[question] Is it the upper clevis to fork bolt that Honda recommends not removing, or is it the clevis to pushrod?

[question] Is it the lower SMC to fork bolt or the lower caliper bolt concealed beneath the seal that needs to be removed?

[question] On my center stand; I'd say the centerline of the outer pistons are inclined already about five degrees; once the correct bolt is removed, will it just swing out the needed 15 degrees, or does it come off completely free of the disk to install an appropriate spacer.

[question] Once I've moved it, would there be enough room to inspect the condition of the parts / clean the exposed pistons?

Do NOT remove the yoke via the 10mm nut, the length of the rod (depth) is preset at the factory, and if it’s off a thread or two it can block the return outlet.

 

[Andrew Shadow]

Is it the upper clevis to fork bolt that Honda recommends not removing, or is it the clevis to pushrod?

Clevis to push-rod is precisely set at the rectory. Don't change it.

Is it the lower SMC to fork bolt or the lower caliper bolt concealed beneath the seal that needs to be removed?

SMC to fork bolt.

There is a bushing that rotates on a needle bearing in there as well. The bushing seizes on the needle bearing if it has not been subjected to maintenance. If the SMC can't rotate on this bushing the SMC can't function. While you are in there clean everything up and regrease the needle bearing and bushing.

will it just swing out the needed 15 degrees, or does it come off completely free of the disk to install an appropriate spacer.

See Larry's answer.