8MMx1.
8MMx1.25 is more common, but not what you want.
Get a couple different lengths.
I picked mine up at Car Quest, since they were close. The clerk was rather befuddled until he tried bolts out of the "other" 8mm drawer.
IF you have a spare spindle or nut, take it with you.
I've made a similar "tool", using a splined BB remover to also hold a PARK HCW 4 in place.
Last edited by Bill Kapaun; 01-22-15 at 09:22 AM.