BOLT CONFUSION

[kaiser]

OK

An 8mm allen key fits a m10 bolt which has a shank(collar) size of 9.85mm(0.387 in). A 3/8 UNC and 3/8 UNF bolt has an O.D of 0.375 in which is marginally smaller than the metric one you are trying.If its a bolt/nut assembly either will do as the shanks should be the same size. Fine threads have higher locking properties whereas coarse threads have a higher torque capabilities. Hope this helps but its quite hard to be sure without seeing it, sorry. How long is the shank you require?

 

[SLIM]

the frame has no thread , the bolt secures with a nut on the other side

the way you have described is correct , with the metric bolt the shank ( unthreaded part ) is too wide , and fouls on the frame as in it wont pass through , not sure if it catches on the bearings or the frame

the non metric is just slightly marrower

so i can either get the bolt shank machined down or the frame or find the correct imperial bolt ( rather difficult so far )

will have to get the frame apart and measure it all up