How to Remove Headless car Bolts
Removing car studs
Studs are headless bolts threaded at both ends with plain metal between or threaded along their whole length.
On the type with a thread at both ends, clamp self-locking grips on the plain section to undo the stud section.
Where there is no threadless section, screw a pair of nuts on the stud and tighten them to lock against each other You can then use a spanner on the lower nut to extract the stud in the same way as undoing a bolt. see fig 1