Tap and Die Sizes for Indian Motorcycles
When restoring your Indian Motorcycle you may wonder what size is that nut or bolt and do I have a tap or die so I can chase the threads.
When Indians were made they used a common pitch size of 24 threads per inch and they didn’t change this no mater the diameter of the bolt. This makes for sizes that are not common today. For example 1/4-24 is not available today. A fine pitch would be 1/4-28 and course 1/4-20. So be careful when chasing those bolts and nuts. Most restoration suppliers will make the correctly threaded bolts and nuts you need to finish your restoration but you still need the proper taps and dies to chase those threads!
Hopefully the table below will help in answering a few of those questions:
| Bolt Size |
Thread Pitch |
Tap Drill Size (inch/mm) |
Die Size |
Notes |
| #10-24 UNC |
24 TPI |
#25 (0.1495″) |
10-24 UNC |
Used for body panels, light brackets |
| 1/4″-20 UNC |
20 TPI |
#7 (0.201″) |
1/4″-20 UNC |
Common for small mounts |
| 5/16″-18 UNC |
18 TPI |
F (0.257″) |
5/16″-18 UNC |
Footpeg mounts, controls |
| 3/8″-16 UNC |
16 TPI |
5/16″ (0.3125″) |
3/8″-16 UNC |
Engine mounting |
| M5 x 0.8 |
0.8 mm |
4.2 mm |
M5 x 0.8 |
Switches, instrument clusters |
| M6 x 1.0 |
1.0 mm |
5.0 mm |
M6 x 1.0 |
Controls, engine cases |
| M8 x 1.25 |
1.25 mm |
6.8 mm |
M8 x 1.25 |
Exhaust mounting, frame brackets |
| M10 x 1.5 |
1.5 mm |
8.5 mm |
M10 x 1.5 |
Axle clamps, suspension linkage |
| M12 x 1.75 |
1.75 mm |
10.2 mm |
M12 x 1.75 |
Larger frame/engine bolts |
| M14 x 1.5 |
1.5 mm |
12.5 mm |
M14 x 1.5 |
Axle nuts, swingarm pivots |
