The quality of the studs used is quite poor and they always corrode quite badly due to the high temperature and wet roads.
When they snap replacement is inevitably difficult and the replacement stud generally seems to be made from a relatively weak material.
The current trend is also to use a cheap Copper Plated 'K' Nut that are being sold on EBay.
I am not sure that using a prevailing torque nut on a weak stud isn't the best idea. The cheap 'flash' copper plate will not really provide much in the way of corrosion resistance and help the replacement stud break again.
We are now changing the studs on all of the heads we refurbish and fitting a stud manufactured from 6AL4V Titanium.
These studs gave a 'dog point' and can be tightened into the head and using a specialist threadlocker will prevent any bi-metallic corrosion.
We have also made a reduced head Titanium Flange Nut to replace the barrel nuts.
We are confident that these studs will be a 'fit once' solution.
