When the collar is torqued between the frame rails, it shortens slightly. The final clearance between the face of the bushings (whether they be the flanged bronze or the separate phenolic type) and the inside of the cup washers will become about 0.002" at 25-ft-lbs of torque on the big bolt, if the collar starts out at 9.130" nominal. On the [early] swingarm bolts that are drilled through the ends to include the grease zerks on both sides, this torque can be higher, like 30-35 ft-lbs, to compress the collar slightly more and improve high-speed handling a tad.
