Later Norton motorcycles used a number of different threadforms, to cause maximum confusion and annoyance. The table below shows many of the more commonly found thread dimensions so that they can be identified.
| THREAD SIZE | DIAMETER | T.P.I. | PITCH | |||
| British | Unified | Metric | Imperial | Metric | ||
| 2 | 0.078 | 1.98 | 63.5 | 0.40 | ||
| 2 UNC | 0.085 | 56 | ||||
| 2 UNF | 0.085 | 64 | ||||
| 2.2 | 0.086 | 2.18 | 56.4 | 0.45 | ||
| 8 BA | 0.086 | 59.1 | 0.43 | |||
| 7 BA | 0.097 | 52.9 | 0.48 | |||
| 2.5 | 0.098 | 2.48 | 56.4 | 0.45 | ||
| 3 UNC | 0.098 | 48 | ||||
| 3 UNF | 0.098 | 56 | ||||
| 6 BA | 0.109 | 47.5 | 0.53 | |||
| 4 UNC | 0.111 | 40 | ||||
| 4 UNF | 0.111 | 48 | ||||
| 3 | 0.117 | 2.98 | 50.8 | 0.50 | ||
| 1/8 BSW | 0.124 | 40 | ||||
| 5 UNC | 0.124 | 40 | ||||
| 5 UNF | 0.124 | 44 | ||||
| 5 BA | 0.125 | 43.1 | 0.59 | |||
| 3.5 | 0.137 | 3.48 | 42.3 | 0.60 | ||
| 6 UNC | 0.137 | 32 | ||||
| 6UNF | 0.137 | 40 | ||||
| 4 BA | 0.141 | 38.5 | 0.66 | |||
| 4 | 0.157 | 3.98 | 36.3 | 0.70 | ||
| 3 BA | 0.160 | 34.8 | 0.73 | |||
| 8 UNC | 0.163 | 32 | ||||
| 8 UNF | 0.163 | 36 | ||||
| 4.5 | 0.177 | 4.48 | 33.9 | 0.75 | ||
| 2 BA | 0.184 | 31.4 | 0.81 | |||
| 3/16 BSW | 0.186 | 24 | ||||
| 3/16 BSF | 0.186 | 32 | ||||
| 10 UNC | 0.189 | 24 | ||||
| 10 UNF | 0.189 | 32 | ||||
| 5 | 0.196 | 4.98 | 31.8 | 0.80 | ||
| 1 BA | 0.208 | 28.2 | 0.90 | |||
| 12 UNC | 0.215 | 24 | ||||
| 12 UNF | 0.215 | 28 | ||||
| 7/32 BSF | 0.218 | 28 | ||||
| 0 BA | 0.235 | 25.4 | 1.00 | |||
| 6 | 0.235 | 5.97 | 25.4 | 1.00 | ||
| 1/4 BSW | 0.249 | 20 | ||||
| 1/4 BSF | 0.249 | 26 | ||||
| 1/4 UNC | 0.249 | 20 | ||||
| 1/4 UNF | 0.249 | 28 | ||||
| 7 | 0.275 | 6.97 | 25.4 | 1.00 | ||
| 9/32 BSF | 0.280 | 26 | ||||
| 5/16 BSW | 0.311 | 18 | ||||
| 5/16 BSF | 0.311 | 22 | ||||
| 5/16 UNC | 0.311 | 18 | ||||
| 5/16 UNF | 0.311 | 24 | ||||
| 8 | 0.314 | 7.97 | 20.3 | 1.25 | ||
| 9 | 0.353 | 8.97 | 20.3 | 1.25 | ||
| 3/8 BSW | 0.374 | 16 | ||||
| 3/8 BSF | 0.374 | 20 | ||||
| 3/8 UNC | 0.374 | 16 | ||||
| 3/8 UNF | 0.374 | 24 | ||||
| 10 | 0.393 | 9.97 | 16.9 | 1.50 | ||
| 11 | 0.431 | 10.97 | 16.9 | 1.50 | ||
| 7/16 BSW | 0.436 | 14 | ||||
| 7/16 BSF | 0.436 | 18 | ||||
| 7/16 UNC | 0.436 | 14 | ||||
| 7/16 UNF | 0.436 | 20 | ||||
| 12 | 0.471 | 11.97 | 14.5 | 1.75 | ||
| 1/2 BSW | 0.499 | 12 | ||||
| 1/2 BSF | 0.499 | 16 | ||||
| 1/2 UNC | 0.499 | 13 | ||||
| 1/2 UNF | 0.499 | 20 | ||||
