If I understand right, you ask about the threaded stud (or screw) for the rocker that links the 2 rods to the rear brake? What measures do you have, What part of the screw do you think is too long, the bearing part or the threaded part? How thick is the lever where the stud goes through, and how long is the bearing part on your frame. I don't have detailed knowledge of the -31 but with those measurements, someone might have an easier time to compare with what they have.