Hi
Possibly 12mm studding is not the best option to use within a bush.
A set bolt would do at a push ( Threadded its entire length )
I would reccommed however that a propper shanked bolt would be the best option for the suspension bush bolts.
I have used some temporary set bolts to move my build about. When I am ready I will try to source some M12 bolts with about 40mm of plain shank & then trim the excess thread back.
Before I get slated, that is just my own personal view
