In the States we call it a "carriage bolt". There's a rounded head
, with no slot, no nothing, and the shank has been squared up underneath the head
so that as is pulls into a piece of wood, the square shank cuts in and locks the head from turning. The head just looks like a rounded rivet head, ornamental for "coach work".
All the turning is down from the nut alone.
You could turn this around: Use another coach bolt, or ANY bolt, and epoxy
the head of the bolt into the timber, so it sticks up through the mounting foot. After the epoxy
dries, just add a regular locking nut and tighten down as needed.
mounts, like all rubber parts
, "should" be replaced after five years. The new mounts will be more supple and absorb more vibration, and of course be less likely to fail. Since one is already unbolted...[g]....