7/16"-14 UNC thread

7/16"-14 UNC is a coarse Unified inch thread with a 11.112 mm (0.437") major diameter and 14 threads per inch (1.814 mm pitch). Tap it with a U drill; drill 11.91 mm to pass a bolt through.

The numbers

Designation

7/16"-14 UNC

Major diameter

11.112 mm / 0.437"

Minor diameter

9.148 mm

Pitch

14 threads per inch (1.814 mm pitch)

Tap drill (75% thread)

U — 9.35 mm

Clearance hole (close fit)

11.91 mm / 0.469"

Hex across flats

15.88 mm

How to measure what you have

1. Measure across the thread crests with calipers. A used 7/16"-14 UNC reads a little under 11.112 mm — the crests are truncated by the standard, then worn and plated, so anything from about 10.7 mm up is consistent with this size.
2. Count the threads crossing one inch. This one gives 14.
3. A thread pitch gauge settles it in seconds and costs very little. Guessing between a coarse and a fine thread of the same diameter is the usual way a thread gets stripped.

Tightening torque

Plain steel property class 8.8 or SAE grade 5, dry threads, tightened to about 65% of yield. Lubricated threads reach the same preload at 20-30% less torque. Where the manufacturer publishes a figure — spark plugs, wheel nuts, cylinder heads — use theirs.

Where this size turns up

• US automotive suspension and driveline bolts
• Trailer frame and axle hardware
• Agricultural implement bolting

Other threads at this diameter