Yes, rode it 4 miles there. Then a couple hours later and after lunch, rode it 5 miles home.
What we did was take off the brake caliper (required pulling the rear axle to loosen the wheel, and taking the mufflers off of both sides),
cleaned everything in that rear brake system, but without draining or flushing fluids. We checked the movement of the pistons which were fine. The brake pads still looked good.
A PROBLEM: but the slider pins had old lubricant encrusted onto them, and they were also scratched up for some reason.
So we polished those by hand with some Emery cloth lube them up, make sure everything else fit in there was clean and greased, then reassembled it.
IT SEEMED TO WORK: I could then spin the rear wheel one full rotation after this work, whereas I could not make it spin at all on its own prior to disassembly--meaning as soon as I took my hand off the wheel, as soon as the propulsion stopped, the wheel would stop too.
THE FIX DIDN'T LAST: Back home, 5 miles later, in my garage, I popped it up on the centerstand and repeated this experiment.
Now I could only spin it 1/3 of a rotation!! (??)
Temperature readings:
On the way to the mechanic's house this morning riding in 35° air temperatures I stopped twice to check the brake rotor both by hand and with a LASER non-contact thermometer. I got readings of around 92 I think 102 Fahrenheit. My bare hand could touch the rear brake rotor for about one second before I had to pull away the front brake rotor was just warm not hot.
On the way back from the mechanics house, well I didn't stop to check the temperature but the air was noticeably warmer like 58 maybe 60°F. As soon as I got home I hopped off the bike and felt the rear brake rotor with my hand --it was hot; it felt just as hot as it did this morning.
My laser thermometer said it was hotter:
120° at first, but within seconds it cooled to 100 and then down into the 90s.
The front rotor was still just barely warm something like 85°F.
"HOUSTON, WE [still] HAVE A PROBLEM!"