Thanks for the lively discussion of caliper rattle. I may have induced rattle when I cleaned and greased the pivot. Some of my bikes have indeed been pressure washed and at least one was left leaned against a clothesline pole for a couple winters before I drug it home.
OK, the Rat Race K1 with dual 76F calipers still has some drag. If I bump the calipers in a bit, it rolls perfectly. I removed them, cleaned and sanded the sides of the pads and got no relief. I checked my notes and I already cleaned and rebuilt both calipers when I assembled the front end a year or so back. That leads me to the master cyl. The holes in the bottom of the reservoir are both open, fluid is clear.
What I don't get is any free play in the Magura lever, I replaced it with a stocker and no change. I checked the other running bikes here, the two made in 69 K0's, known to have original M/C's both have freeplay, of a few newer bikes, none have any.
Well, I remembered that I promised to try every suggestion you guys made so I replaced everything inside the calipers and stole a M/C off my "parted in" CB750 K0. The braided lines are a year old, should still be good and now I can compress the lever and when it returns, the calipers are not dragging.
The pistons reminded me of a member that had his caliper seals melt and stick to the piston. One had a black ring around it and the other had icky yuck on it but not in a ring.
My brand X mighty vac made short work of the bleeding process and once again it went so fast it sucked air. Do-over time.
