Operation CHARM: Car repair manuals for everyone.

Unified Thread Identification





1. Bolts:
A circular recess is stamped in the upper surface of the bolt head.
2. Nuts:
A continuous line of circles is indented on one of the flats of the hexagon, parallel to the axis of the nut.
3. Studs, Brake Rods, etc.:
The component is reduced to the core diameter for a short length at its extremity.