If anyone is interested in actual manufacturer-sponsored research instead of quoting moldy old service manuals, I'll tell you about a project I participated in with a bunch of other trade school instructors in cooperation with the GM training center in Memphis Tennessee. Some of the early disc brake systems in the late 1960's and early 70's were experiencing brake shudder and uneven disc wear. In a research effort that included trade school instructors from several states, (including my father and me) it was found that putting approximately 60-72 inch/lbs. of torque on the spindle nut eliminated the shudder and improved the wear characteristics of the discs. The previous "tighten- - - -then back off") procedure appeared to be the cause of the problem. I see no reason something similar might be happening here, and sanding/grinding the nut to reduce the amount it needs to be backed off to get a cotter pin installed should be a viable solution.
Jerry
