I have a 1988 Trek 660 with Shimano 600 Ultegra with a worn bottom bracket. The spindle size is 68 x 116 with 1.37 x 24 shell threading. I was thinking of using the Shimano BB-UN54 however the closet size is 68 x 115. What kind of problems (adjustments) will the 115 (vs. the existing 116) create?