Piston Rod for Master Cylinder

[Fourcandles]

Hi All,

I know i'm asking a lot of questions at the moment your help is greatly appreciated.

I'm just looking into what I need to make the piston rod for the brake master cylinder and I seem to remember someone saying you can use an M8 bolt but then i've read somewhere else to use an M6 bolt of over 6" in lenthgh and cut it down..

Surely an M8 is 8mm and an M6 6mm just wondered what everyone else has used?

Many Thanks,