Threads

The table lists SAE threads (A) and their respective core drills in SAE measures (B) and in mm (C).

Screws with thread diameters smaller than 1/4” are not denoted with fractional numbers but follow the SAE number system. Example: size denotation 10-24. The number 10 describes the diameter which is 4.8 mm according to the chart. The number 24 regularly indicates threads per inch.

Thread particulars for tube connectors most often contain three letters: NPT. NPT stands for National Pipe Thread. In contrary to other threads, the fractional number before the dash has little to do with theactual diameter, and - what's more - on a keen inspection of the thread you'll see that it is conical. For your convenience follows a table of the most common pipe threads on Harleys: