A shop technique for driving a headless stud or threaded rod. Two nuts are run on and tightened hard against each other; turning the upper nut clockwise installs the stud, and turning the lower nut counterclockwise removes it. A stud extractor socket does the job faster, but double-nutting works with any nuts that fit.
Double-nut the exhaust stud and back it out with the bottom nut, and if it fights you, heat the boss first.
Also heard as
- double nut
- jamming two nuts
Related terms
Stud
A headless rod threaded at both ends or along its full length, used with nuts or screwed into a tapped hole.
Jam nut
A thin nut, roughly half to two-thirds standard height, run up against another nut or part to stop it turning.
All-thread
Shop name for threaded rod: steel bar threaded end to end, cut to length for hangers, anchors and long studs.