there transmission case interference issues with a larger diameter. the 8x1.25 nut has a nominal thread thickness, I will ensure that that stays the same for thread engagement. may be able to make the pulley thicker though for additional thread area. Dont remember why i was doing it that way. dont have the parts in front of me. on a separate note: porsche boxter transaxle. I was thinking about using one for my other build. anything i should know?